Lecture 1

Question 1

Name three organs in the following systems:
Basic embryology
CVS
Musculoskeletal
Nervous
Digestive

What does basic anatomy involve

Answer 1

Systems
•Urogenital system:
Basic embryology: (Gametogenesis; spermatogenesis, oogenesis, fertilization)
•Cardiovascular system (Heart and great vessels, systemic and pulmonary circulation)
•Musculoskeletal system (Osteology, framework of the human skeleton, muscle types, types of joint)
•Nervous system (neurones/nerve cells: types: multipolar, bipolar and pseudounipolar; parts: axons, dendrites, myeline sheath,
•Digestiive system: oral cavity, teeth, tongue, GI tract

Basic anatomy of the human body involves understanding the structure and organization of body systems, organs, tissues, cavities, joints, bones, blood vessels, and nerves.

Question 2

What is human anatomy

Answer 2

Human anatomy is the science concerned with the structure of
the human body.

The term is derived from a Greek word meaning “to cut up”.
In ancient times, the word anatomize was more commonly used than the word dissect.

Question 3

What is a body system
Which organs serve two systems?

Answer 3

A body system consists of various organs that have similar or related functions e.g.
•skeletal system
•circulatory system
•nervous system
•digestive system
•respiratory system

Certain organs may serve two systems e.g., the pancreas functions with both the endocrine and digestive systems. Which others?
Pharynx serves both the respiratory and digestive systems. Pharynx to larynx to trachea. The glottis is in the larynx and epiglottis is a leaf shaped flap that covers the glottis in the larynx to prevent food from entering the larynx and trachea. Then in digesting, it is pharynx and oesophagus
All the systems are interrelated and function together to make up the organism.

1. Pancreas:
   
   • Digestive System: It produces digestive enzymes (amylase, lipase, proteases) that are secreted into the small intestine to aid in digestion.
   • Endocrine System: It produces hormones such as insulin and glucagon, which regulate blood sugar levels.
2. Liver:
   
   • Digestive System: It produces bile, which helps break down fats in the digestive process.
   • Circulatory System: It processes nutrients absorbed from the digestive tract and detoxifies harmful substances in the blood.
3. Thymus:
   
   • Immune System: It is involved in the maturation of T-cells, a type of white blood cell critical for immune response.
   • Endocrine System: It secretes hormones like thymosin that stimulate the development of T-cells.
4. Gonads (Testes/Ovaries):
   
   • Reproductive System: They produce gametes (sperm in males, eggs in females).
   • Endocrine System: They secrete sex hormones, such as testosterone in males and estrogen and progesterone in females.
5. Hypothalamus:
   
   • Nervous System: It regulates many autonomic functions like hunger, thirst, and body temperature.
   • Endocrine System: It controls the pituitary gland and regulates the release of various hormones.
6. Kidneys:
   
   • Urinary System: They filter blood to remove waste and produce urine.
   • Endocrine System: They secrete hormones like erythropoietin (which stimulates red blood cell production) and renin (which helps regulate blood pressure).

These organs highlight the body’s interconnected nature, where one organ can play crucial roles in multiple physiological processes.

In the digestive system, the pancreas performs several crucial functions:

1. Production of Digestive Enzymes: The pancreas produces digestive enzymes that are secreted into the small intestine. These enzymes include:
   
   • Amylase: Breaks down carbohydrates into simple sugars.
   • Lipase: Breaks down fats into fatty acids and glycerol.
   • Proteases (such as trypsin and chymotrypsin): Break down proteins into peptides and amino acids.
2. Production of Bicarbonate: The pancreas secretes bicarbonate ions into the small intestine. This neutralizes the acidic chyme (partially digested food) coming from the stomach, creating an optimal pH environment for the enzymes to function effectively.

Question 4

What is another name for developmental anatomy?
What about microscopic anatomy?
What about macroscopic anatomy?
Human body has 206 bones

Answer 4

Developmental anatomy- embryology
Microscopic anatomy- histology
Macroscopic anatomy- Gross anatomy(example reproductive system having the testes, fallopian tubes ,etc)

Question 5

Gametogenesis involves which two processes?

Answer 5

1.spermatogenesis
2. Oogenesis

Question 6

Explain spermatogenesis (meiosis is usually for sex cells. Learn also about meiosis and mitosis)
How many spermatids does the primary spermatocyte produce?

Which part of the process is mitotic division and which part is meiotic division?
What are the three main phases of spermatogenesis ?
Where does spermatogenesis occur in the testes
Difference between spermatogenesis,spermiogenesis and spermatocytogenesis
What is the function of FSH,LH and testosterone in spermatogenesis
State the processes involved in maturation of the spermatids

Answer 6

Spermatogenesis is the process by which male gametes, known as spermatozoa or sperm cells, are produced in the testes. This complex and highly regulated process involves several stages of cell division and differentiation, occurring within the seminiferous tubules of the testes. Spermatogenesis can be divided into three main phases: spermatocytogenesis, meiosis, and spermiogenesis.

This phase involves the proliferation and differentiation of spermatogonia (the sperm precursor cells) into primary spermatocytes. It includes the following steps:
- Spermatogonia: These are stem cells located at the base of the seminiferous tubules. They undergo mitotic divisions to produce more spermatogonia, some of which will differentiate into primary spermatocytes.
- Primary Spermatocytes: These cells undergo the first meiotic division to form secondary spermatocytes.

Meiosis is a two-step division process that reduces the chromosome number by half, resulting in the formation of haploid cells:
- First Meiotic Division: Primary spermatocytes undergo meiosis I to produce two secondary spermatocytes, each with half the number of chromosomes (haploid).(total is 46 chromosomes so haploid is 23)
- Second Meiotic Division: Each secondary spermatocyte undergoes meiosis II to produce two spermatids. Thus, a single primary spermatocyte gives rise to four spermatids.

Spermiogenesis is the final phase where spermatids differentiate into mature spermatozoa:
- Nuclear Condensation: The chromatin in the nucleus becomes highly condensed.
- Acrosome Formation: An acrosome, a cap-like structure that contains enzymes necessary for fertilization, forms over the nucleus.
- Flagellum Development: The cell develops a flagellum (tail) that provides motility.
- Cytoplasmic Reduction: Excess cytoplasm is removed.
- Mitochondrial Organization: Mitochondria arrange themselves in the midpiece of the sperm to provide energy for movement.

Spermatogenesis is regulated by several hormones:
- Follicle-Stimulating Hormone (FSH): Stimulates the spermatogonia to initiate spermatogenesis.
- Luteinizing Hormone (LH): Stimulates the Leydig cells in the testes to produce testosterone.
- Testosterone: Essential for the progression of spermatogenesis and the maturation of spermatozoa.

Spermatogenesis is the process of sperm cell production in males, taking place in the seminiferous tubules of the testes. It involves the differentiation of spermatogonia into spermatocytes, meiotic divisions to produce haploid spermatids, and the transformation of spermatids into mature, motile spermatozoa. This process is intricately regulated by hormones, including FSH, LH, and testosterone.

M Spermatocytogenesis and spermatogenesis are related but not identical processes.

Definition: Spermatogenesis is the comprehensive process of sperm development. It includes all stages from the initial spermatogonial stem cells to the mature spermatozoa.

Stages:
1. Spermatocytogenesis: The first phase of spermatogenesis. It involves the proliferation and differentiation of spermatogonia into primary and secondary spermatocytes.
2. Spermiogenesis: The final phase of spermatogenesis, where spermatids mature into spermatozoa (sperm cells). This includes the development of the sperm’s head, midpiece, and tail.

Definition: Spermatocytogenesis is a subset of spermatogenesis, specifically focusing on the stages involving the transformation of spermatogonia into primary and secondary spermatocytes, and eventually into spermatids.

Key Points:
- Spermatocytogenesis: Includes the proliferation of spermatogonia and their progression through meiosis to form spermatocytes.
- Spermatogenesis: Encompasses both spermatocytogenesis and spermiogenesis, representing the full spectrum of sperm development from stem cells to mature spermatozoa.

• Spermatocytogenesis is part of spermatogenesis. It covers the early stages of sperm development involving the formation of spermatocytes.
• Spermatogenesis includes both spermatocytogenesis and spermiogenesis, covering the entire process from the initial germ cells to fully mature sperm cells.

Question 7

What are the different types of spermatogonia and state their functions

Answer 7

Spermatogonia are the precursor cells in spermatogenesis, and they are categorized into different types based on their roles and characteristics. The primary types are Type A and Type B spermatogonia.

Type A spermatogonia are further divided into Type A dark (Ad) and Type A pale (Ap) based on their appearance and function.

1. Type A Dark (Ad) Spermatogonia:
   
   • Role: Type A dark spermatogonia function as stem cells within the seminiferous tubules. They are responsible for maintaining the pool of spermatogonia through self-renewal.
   • Characteristics: These cells have dense, dark-staining nuclei, indicating their relatively inactive state. They divide infrequently and ensure a continuous supply of spermatogonia.
2. Type A Pale (Ap) Spermatogonia:
   
   • Role: Type A pale spermatogonia are committed to differentiating into sperm cells. They serve as progenitor cells that will eventually give rise to Type B spermatogonia.
   • Characteristics: These cells have lighter-staining nuclei compared to Type A dark spermatogonia. They undergo mitotic divisions more frequently than Type A dark cells.

• Role: Type B spermatogonia are the next stage in the differentiation process. They are derived from Type A pale spermatogonia and are destined to become primary spermatocytes.
• Characteristics: These cells have rounder and less dense nuclei than Type A spermatogonia. They will undergo further mitotic divisions before entering meiosis to form primary spermatocytes.

• Type A Dark (Ad) Spermatogonia: These are the stem cells of the spermatogenic lineage, characterized by dark-staining nuclei and infrequent division. They ensure the self-renewal and maintenance of the spermatogonial population.
• Type A Pale (Ap) Spermatogonia: These cells are progenitors committed to differentiation, characterized by lighter-staining nuclei. They give rise to Type B spermatogonia.
• Type B Spermatogonia: These cells are derived from Type A pale spermatogonia and will differentiate into primary spermatocytes, entering meiosis to eventually form spermatozoa.

Understanding these cell types and their roles is crucial for comprehending the complex process of spermatogenesis and the maintenance of male fertility.

The transition from Type A (pale) spermatogonia to Type B spermatogonia is a crucial step in spermatogenesis. Here’s how this transition occurs:

1. Type A (Pale) Spermatogonia
   
   • Characteristics: Type A (pale) spermatogonia are more differentiated than Type A (dark) spermatogonia and are actively involved in preparing for meiosis. They are also known as intermediate spermatogonia.
   • Function: These cells are committed to entering the spermatogenic pathway and do not renew themselves as Type A (dark) spermatogonia do.
2. Differentiation into Type B Spermatogonia
   
   • Mitosis: Type A (pale) spermatogonia undergo mitotic divisions. During this process, some of these cells differentiate into Type B spermatogonia.
   • Characteristics of Type B Spermatogonia: Type B spermatogonia are larger and more advanced in differentiation compared to Type A (pale) spermatogonia. They are committed to entering meiosis and eventually forming primary spermatocytes.
   • Role of Type B Spermatogonia: They will further divide to form primary spermatocytes, which then undergo meiosis to produce secondary spermatocytes and ultimately spermatids.

• Transition: Type A (pale) spermatogonia differentiate into Type B spermatogonia through mitotic division.
• Outcome: Type B spermatogonia are the direct precursors to primary spermatocytes, marking the beginning of the meiotic phase of spermatogenesis.

Question 8

What is Capacitation
Where does Capacitation occur
What two things are removed from the plasma membrane that overlies the acrosome?
Capacitated sperms show morphologic changes true or false?

Answer 8

It is a period of conditioning in the female reproductive tract (lasts about 7 hours).

•Entails epithelial interactions between the sperm and mucosal surface of the uterine tube.

•Glycoprotein coat and seminal plasma proteins are removed from the plasma membrane that overlies the acrosome.

False.
•Capacitated sperms show NO morphologic changes, but they are more active.

Capacitation is crucial for successful fertilization for several reasons:

1. Acrosome Reaction Preparation:
   
   • Essential for Penetration: Capacitation prepares the acrosome of the sperm to undergo the acrosome reaction. This reaction involves the release of enzymes that are necessary for the sperm to penetrate the zona pellucida, the protective layer surrounding the egg.
2. Membrane Fluidity:
   
   • Facilitates Fusion: Capacitation increases the fluidity of the sperm membrane, which is vital for the sperm to fuse with the egg’s membrane. The increased membrane fluidity helps the sperm’s acrosome to interact effectively with the zona pellucida.
3. Ion and pH Changes:
   
   • Triggers Reaction: Capacitation induces changes in ion concentrations (such as calcium) and pH within the sperm. These changes trigger the acrosome reaction and enhance the sperm’s motility and ability to reach the egg.
4. Enhanced Motility:
   
   • Improves Sperm Function: Capacitation improves sperm motility, making it more likely that the sperm will reach and fertilize the egg.
5. Binding and Recognition:
   
   • Sperm-Egg Recognition: Capacitation also prepares the sperm to bind with specific receptors on the zona pellucida of the egg, ensuring that the sperm and egg can recognize and bind to each other.

Capacitation is vital because it equips the sperm with the necessary physiological changes to successfully penetrate the egg’s outer layers and achieve fertilization. Without capacitation, sperm would be unable to interact effectively with the egg, making fertilization unlikely.

No, the acrosome itself is not removed during capacitation. Instead, capacitation involves changes to the acrosome that prepare the sperm for fertilization. Here’s a breakdown of what happens:

Capacitation

Definition: Capacitation is a physiological process that sperm undergo in the female reproductive tract (or in vitro) that is necessary for fertilization. It involves several key changes:

1.	Changes in the Acrosome:
•	Acrosome Reaction: Capacitation triggers the acrosome reaction, where the acrosome (a cap-like structure covering the head of the sperm) becomes more permeable and undergoes biochemical changes.
•	Enzyme Release: The acrosome releases digestive enzymes, such as hyaluronidase and acrosin, which help the sperm penetrate the zona pellucida (the protective layer surrounding the egg

Question 9

What is Capacitation

Capacitated sperms show morphologic changes true or false?

Answer 9

It is a period of conditioning in the female reproductive tract (lasts about 7 hours).

•Entails epithelial interactions between the sperm and mucosal surface of the uterine tube.

•Glycoprotein coat and seminal plasma proteins are removed from the plasma membrane that overlies the acrosome.

False.
•Capacitated sperms show NO morphologic changes, but they are more active.

Question 10

How do Sertoli and leydig cells come together for spermatogenesis
What is spermeogenesis?
Sertoli cells come in two types,columnar and squamous cells. Which of them form part of the structural support within the seminiferous tubules and which of them provide physical support and create a nurturing environment for the developing germ cells.
State four
Functions of Sertoli cells

Answer 10

Sertoli cells come in squamous or flat cells and Columnar cells are like a column or long
Sertoli cells nourish the germ cells till they become spermatids
Spermeogenesis- developing the head of the sperm properly

Sertoli cells, also known as “nurse cells,” play a crucial role in the process of spermatogenesis by supporting and nourishing the developing germ cells. Here are the key points about Sertoli cells and their function:

• Squamous (Flat) Sertoli Cells: These cells are characterized by their flat shape. They form part of the structural support within the seminiferous tubules.
• Columnar Sertoli Cells: These cells are elongated and column-like. They provide physical support and create a nurturing environment for the developing germ cells.

• Nourishment: Sertoli cells supply nutrients and regulatory signals to the germ cells as they progress through different stages of development, from spermatogonia to spermatids.
• Blood-Testis Barrier: They form tight junctions, creating a blood-testis barrier that protects germ cells from harmful substances and immune responses.
• Phagocytosis: Sertoli cells help remove residual cytoplasm and other cellular debris during spermatogenesis.
• Secretion: They secrete various substances such as androgen-binding protein (ABP) and inhibin, which are important for regulating the hormonal environment of the testes.

Spermiogenesis is the final stage of spermatogenesis, where spermatids undergo morphological and structural changes to become mature spermatozoa. Key processes in spermiogenesis include:

1. Nuclear Condensation: The chromatin in the spermatid’s nucleus becomes highly condensed, making the nucleus more compact.
2. Acrosome Formation: An acrosome, which is a cap-like structure containing enzymes necessary for fertilization, forms over the nucleus.
3. Flagellum Development: The development of the flagellum (tail) provides the sperm with motility, enabling it to swim towards the egg.
4. Cytoplasmic Reduction: Excess cytoplasm is removed, resulting in a streamlined cell structure.
5. Mitochondrial Organization: Mitochondria arrange themselves in the midpiece of the sperm to provide the energy needed for movement.

• Sertoli Cells: These essential support cells in the testes come in two forms, squamous (flat) and columnar (elongated). They provide nourishment, structural support, and regulatory signals to developing germ cells, ensuring the proper progression of spermatogenesis.
• Spermiogenesis: This is the final stage of spermatogenesis, during which spermatids undergo significant morphological changes to become mature, motile spermatozoa. The process includes the formation of a compact nucleus, the development of the acrosome and flagellum, cytoplasmic reduction, and mitochondrial organization.

Together, these processes ensure the production of healthy and functional sperm cells, critical for male fertility and successful reproduction.

Question 11

Progenitor cell are very similar to stem cells. They are biological cells and like stem cells, they too have the ability to differentiate into a specific type of cell. However, they are already more specific than stem cells and can only be pushed to differentiate into its “target” cells
True or false

Answer 11

True

Question 12

Explain Oogenesis
Oogenesis starts at puberty. True or false
At which points does mitosis happen?
What about meiosis
What are the chromosome numbers at each point

Answer 12

In oogenesis, only one of the four haploid daughter cells formed after meiosis becomes a functional egg (secondary oocyte), while the other three become polar bodies, which eventually degenerate. Here’s how it works:

1. Primary Oocyte (Diploid): The process begins with a primary oocyte, which is arrested in prophase I during fetal development.
2. Meiosis I: Upon ovulation, the primary oocyte completes the first meiotic division, which produces two haploid cells: a secondary oocyte and a first polar body. The secondary oocyte receives most of the cytoplasm, while the first polar body is much smaller and usually degenerates.
3. Meiosis II: The secondary oocyte begins the second meiotic division, but it pauses at metaphase II. If fertilization occurs, the secondary oocyte completes meiosis II, resulting in the formation of a fertilized ovum and a second polar body. If fertilization does not occur, the secondary oocyte will not complete meiosis II.

Thus, while four haploid cells are technically produced, only one becomes a functional egg, and the other three (the first polar body and potentially two additional polar bodies from its division) are non-functional and eventually degenerate.

Primordial germ cells(undergo mitosis),oogonia(undergo mitosis),primary oocyte(starts meiosis I but doesn’t complete.gets arrested in prophase I so it’s diploid. Only completes when puberty hits) ,first polar body and secondary oocyte(these are haploid. Polar body has 23 and secondary oocyte has 23 chromosomes. Secondary oocyte starts meiosis II but gets arrested in metaphase II and continues when fertilization occurs ) ootid,second polar body and ovum.

Oogenesis is the process by which female gametes, or ova (egg cells), are produced in the ovaries. This process includes several critical stages: the formation of oogonia, development of primary oocytes, meiotic divisions, and maturation of the ovum. Each stage involves specific changes in chromosome numbers and the formation of polar bodies.

• Prenatal Development: Oogenesis starts during fetal development. Primordial germ cells migrate to the developing ovaries, where they differentiate into oogonia.
• Proliferation: Oogonia undergo several rounds of mitotic division to increase their number. Each oogonium is diploid (2n), with 46 chromosomes.

• Growth and Differentiation: Some oogonia grow larger and differentiate into primary oocytes. These cells enter the first meiotic division but get arrested in prophase I.
• Chromosome Number: Each primary oocyte is diploid (2n) with 46 chromosomes.

• Resumption at Puberty: With the onset of puberty, hormonal changes stimulate a small number of primary oocytes to resume meiosis I each menstrual cycle.
• Completion of Meiosis I: Each primary oocyte completes meiosis I to form two unequal daughter cells:
  
  • Secondary Oocyte: The larger cell, which retains most of the cytoplasm, becomes the secondary oocyte.
  • First Polar Body: The smaller cell, called the first polar body, usually degenerates.
• Chromosome Number: After meiosis I, the secondary oocyte and the first polar body each have 23 chromosomes (haploid, n), but each chromosome consists of two sister chromatids.

• Arrest in Metaphase II: The secondary oocyte begins meiosis II but gets arrested in metaphase II. It remains in this state until fertilization.
• Ovulation: The secondary oocyte is released from the ovary during ovulation.
• Fertilization: If a sperm cell penetrates the secondary oocyte, meiosis II resumes and completes. This results in the formation of two cells: OOTID AND SECOND POLAR BODY. The OOTID then matures to the ovum and by the time it matures to the ovum, the second polar body is already discarded
  
  • Ovum (Mature Egg): The larger cell that retains most of the cytoplasm.
  • Second Polar Body: A smaller cell that usually degenerates.
• Chromosome Number: After meiosis II, the ovum and the second polar body each have 23 chromosomes (haploid, n), with each chromosome consisting of a single chromatid.

You’re correct; there’s a nuanced distinction here. Let’s clarify the stages:

1. Secondary Oocyte: The secondary oocyte is arrested in metaphase II of meiosis until fertilization occurs.
2. Fertilization: When a sperm cell penetrates the secondary oocyte, it triggers the completion of meiosis II.
3. Ootid: The completion of meiosis II results in the formation of an ootid and the second polar body. The ootid quickly matures into an ovum.
4. Ovum: The term “ovum” refers to the mature egg cell that is ready for the fusion of genetic material from the sperm and the egg.
5. Zygote: After the sperm and the ovum nuclei fuse, the cell is no longer referred to as an ovum but as a zygote. This is the one-cell stage of the embryo.

So, if the MCQ is asking about the immediate products of the secondary oocyte completing meiosis II, the answer should be “ootid and second polar body”. The term “ovum” is used for the mature egg just before the fusion of genetic material, and “zygote” is used once fertilization is complete.

1. Oogonia (2n = 46 chromosomes): Mitotic proliferation before birth.
2. Primary Oocytes (2n = 46 chromosomes): Arrested in prophase I from prenatal development until puberty.
3. Secondary Oocyte and First Polar Body (n = 23 chromosomes): Formed after completion of meiosis I at puberty; each with 23 chromosomes, each consisting of two sister chromatids.
4. Ovum and Second Polar Body (n = 23 chromosomes): Formed after completion of meiosis II upon fertilization; each with 23 chromosomes, each consisting of a single chromatid.

Oogenesis is a multi-stage process that begins before birth and continues through a female’s reproductive years. Key stages include:

• Formation of Oogonia: Diploid cells that undergo mitosis.
• Primary Oocyte Formation: Diploid cells arrested in prophase I until puberty.
• Meiosis I: Results in a haploid secondary oocyte and the first polar body, each with 23 chromosomes (two chromatids each).
• Meiosis II: Upon fertilization, produces a mature ovum and the second polar body, each with 23 chromosomes (one chromatid each).

This process is essential for female fertility and the production of viable egg cells.

Question 13

What is the zona pellucida?
Which cells produce the zona pellucida ?
What do these cells convert using the theca interna to create estrogen
What is called the primordial follicle?(oogonia? Primary oocyte? Secondary oocyte?)

Which hormone helps the egg cell finish its first meiotic division?

Answer 13

Oogenesis is the process by which ova (egg cells) are produced in the ovaries. This process involves several stages of cell development and differentiation, and it happens in two main phases that overlap in timing.

• Oogonia Formation: During fetal development, primordial germ cells migrate to the ovaries and differentiate into oogonia.
• Mitosis: Oogonia proliferate by mitotic divisions, increasing their number.

• Primary Oocyte Formation: Oogonia differentiate into primary oocytes before birth and begin meiosis I, becoming arrested in prophase I until puberty.
• Follicle Development: Each primary oocyte is enclosed by a layer of follicle cells, forming a primordial follicle.

• Follicle Cell Changes: The follicle cells surrounding the primary oocyte initially start as simple squamous epithelial cells.
• Transformation to Cuboidal Cells: As the follicle develops, these cells become cuboidal in shape, forming a primary follicle.
• Formation of Granulosa Cells: The follicle cells proliferate and stratify, becoming granulosa cells.

• Glycoprotein Production: Granulosa cells begin producing glycoproteins, which form a thick extracellular matrix around the oocyte.
• Zona Pellucida: This glycoprotein layer becomes the zona pellucida, a protective shell around the oocyte essential for fertilization.

• Theca Cell Formation: The surrounding stromal cells differentiate into two layers, the theca interna and theca externa.
  
  • Theca Interna: The inner layer, responsible for producing androgens, which granulosa cells convert into estrogens.
  • Theca Externa: The outer fibrous layer, providing structural support.

• Meiotic Resumption: LH, released from the anterior pituitary gland, triggers the primary oocyte to resume meiosis I.
• Completion of Meiosis I: The primary oocyte completes meiosis I, resulting in two unequal cells:
  
  • Secondary Oocyte: The larger cell that retains most of the cytoplasm.
  • First Polar Body: The smaller cell, which usually degenerates.

• Arrest in Metaphase II: The secondary oocyte begins meiosis II but arrests in metaphase II.
• Ovulation: The secondary oocyte is released from the ovary during ovulation.
• Fertilization: If a sperm cell fertilizes the secondary oocyte, it completes meiosis II, forming an ovum and a second polar body.

1. Phases of Oogenesis: Oogenesis occurs in prenatal and postnatal phases, beginning with oogonia formation and continuing with primary oocyte maturation.
2. Follicle Development: Follicle cells transition from simple squamous to cuboidal and then stratify into granulosa cells, forming the zona pellucida.
3. Theca Layers: The theca interna and externa develop around the follicle, playing roles in hormone production and structural support.
4. Hormonal Regulation: LH is critical for resuming meiosis I and triggering ovulation.

Oogenesis happens in two phases but at the same time.
Primary oocyte starts with being simple squamous then continues to become cuboidal then becomes stratified as it continues maturing . The stratified cells start producing granulosa cells which start producing glycoprotein which surrounds the oocyte. When the glycoprotein surrounds the oocyte, that zone becomes the zona pellucida.

LH helps the cell finish it’s first meiotic division

Question 14

What is an ootid and what is its place in Oogenesis

Answer 14

An ootid is the penultimate(The term “penultimate” refers to something that is second to last in a sequence or series. For example, in a list of ten items, the penultimate item would be the ninth item.) stage in the development of a female gamete (egg cell) during oogenesis. Here’s a detailed explanation of the process leading to the formation of an ootid and its subsequent development:

1. Oogonia Formation:
   
   • Oogonia are the initial germ cells found in the ovaries during fetal development.
   • These cells undergo mitotic divisions to produce a large number of oogonia.
2. Primary Oocyte Formation:
   
   • Some oogonia differentiate into primary oocytes.
   • Primary oocytes begin meiosis I but get arrested in prophase I and remain in this arrested state until puberty.
3. Completion of Meiosis I:
   
   • At puberty, hormonal signals (especially the surge of luteinizing hormone, LH) stimulate a primary oocyte to resume meiosis I.
   • The primary oocyte completes meiosis I, resulting in two cells: a large secondary oocyte and a small first polar body.
4. Secondary Oocyte and Arrest in Meiosis II:
   
   • The secondary oocyte begins meiosis II but is arrested in metaphase II.
   • This cell is ovulated and remains arrested in this stage until fertilization occurs.
5. Completion of Meiosis II and Formation of Ootid:
   
   • If fertilization occurs, the secondary oocyte completes meiosis II.
   • The completion of meiosis II results in the formation of an ootid and a second polar body.

• Haploid Cell: The ootid is haploid (n), meaning it has 23 chromosomes in humans. Each chromosome consists of a single chromatid.
• Transitional Stage: The ootid is a transitional cell, which quickly matures into an ovum.
• Maturation: The ootid undergoes a brief period of maturation, during which it transforms into a mature ovum (egg cell).

• Ovum: The mature ovum is the final product of oogenesis, capable of fusing with a sperm cell during fertilization.
• Fertilization: Upon fertilization, the ovum’s nucleus combines with the sperm nucleus to form a zygote, which will undergo multiple cell divisions to develop into an embryo.

• Oogonia: Initial germ cells.
• Primary Oocyte: Arrested in prophase I until puberty.
• Secondary Oocyte: Arrested in metaphase II and ovulated.
• Ootid: Formed after the secondary oocyte completes meiosis II upon fertilization; it is a transitional stage.
• Ovum: Mature egg cell ready for fertilization.

An ootid represents a crucial transitional stage in the development of a mature egg cell, bridging the gap between the completion of meiosis and the formation of a fully functional ovum.

Question 15

Why is capitation important?
What allows the vagina to contract to allow soerm to move to the ovum?
What process involves biochemical and physiological changes that enhance the sperm’s motility and its ability to penetrate the egg?
What does the matured ovum release to attract the sperm?
What makes it easier for the sperm to move faster ?

Answer 15

Capacitation is a critical process that sperm must undergo to become capable of fertilizing an egg. This process involves biochemical and physiological changes that enhance the sperm’s motility and its ability to penetrate the egg. Here is a detailed explanation of capacitation and the mechanisms by which sperm move from the vagina to the egg to achieve fertilization:

• Definition: Capacitation is the process by which spermatozoa gain the ability to fertilize an ovum after being deposited in the female reproductive tract.
• Biochemical Changes: During capacitation, glycoproteins and other molecules on the surface of the sperm are removed. This removal is crucial for enhancing sperm motility and preparing the sperm for the acrosome reaction, which is essential for penetrating the zona pellucida of the egg.
• Location: Capacitation typically occurs in the uterine tubes or fallopian tubes, where the environment supports these changes.id asked to pick two locations, ire fallopian tubes and it’s cervix

• Initial Deposition: During ejaculation, sperm are deposited in the vagina near the cervix.
• Prostaglandins in Semen: Semen contains prostaglandins, which stimulate contractions of the uterine and fallopian tube muscles. These contractions help propel sperm towards the egg.
• Cervical Mucus: Around ovulation, cervical mucus becomes thinner and more elastic, facilitating the passage of sperm through the cervix into the uterus.
• Uterine Contractions: Uterine contractions, stimulated by prostaglandins and female orgasm, aid in transporting sperm through the uterus towards the fallopian tubes.

• Chemoattractants: The mature ovum releases chemical signals known as chemoattractants. These molecules create a chemical gradient that attracts capacitated sperm, guiding them towards the egg.
• Thermotaxis and Chemotaxis: Sperm can sense both temperature differences (thermotaxis) and chemical gradients (chemotaxis) in the female reproductive tract, helping them navigate towards the egg.

1. Capacitation: Removal of glycoproteins and other molecules from the sperm’s surface enhances its motility and prepares it for the acrosome reaction.
2. Prostaglandins in Semen: These molecules stimulate uterine and fallopian tube contractions, aiding sperm movement towards the egg.
3. Chemoattractants Released by the Ovum: Chemical signals from the ovum attract sperm, guiding them to the egg for potential fertilization.
4. Uterine and Fallopian Tube Contractions: These contractions, influenced by prostaglandins and the female reproductive system, help propel sperm from the vagina to the egg.

1. Vaginal Entry: Sperm are deposited in the vagina near the cervix during ejaculation.
2. Cervical Passage: Sperm swim through the cervical mucus, which is more permeable around ovulation.
3. Uterine Transit: Sperm are propelled through the uterus by muscular contractions and their own motility.
4. Fallopian Tube Arrival: Sperm reach the fallopian tubes, where capacitation completes.
5. Egg Location: Attracted by chemoattractants, capacitated sperm move towards the egg in the fallopian tube.
6. Fertilization: If a sperm successfully penetrates the zona pellucida of the ovum, it fuses with the egg, resulting in fertilization and the formation of a zygote.

Capacitation and the journey of sperm from the vagina to the egg involve a series of coordinated events and changes. These processes ensure that sperm are adequately prepared and guided to the egg, increasing the likelihood of successful fertilization.

Question 16

Explain the process of fertilization
What three layers must the sperm penetrate to reach the egg
What enzymes does the sperm cell release to digest the zona pellucida?
State the layers from the outside to the inside that cover the oocyte

Answer 16

Fertilization is the process by which a sperm cell fuses with an egg cell (oocyte) to form a fertilized egg or zygote. Here’s a step-by-step explanation of human fertilization:

1. Sperm Transport: Sperm are deposited in the female reproductive tract through ejaculation during sexual intercourse. They travel through the cervix and into the uterus, aided by cervical mucus and uterine contractions.
2. Navigating the Female Reproductive Tract: Sperm move through the uterus and into the fallopian tubes (oviducts or uterine tubes), where fertilization occurs. This journey is facilitated by chemical signals and muscular contractions of the female reproductive tract.
3. Encounter with the Oocyte: When a mature egg (oocyte) is released from the ovary during ovulation, it is surrounded by cumulus cells and the corona radiata. Sperm must penetrate these layers to reach the egg. Actually, cumulus cells and the corona radiata are layers that sperm must pass through to fertilize the oocyte. Here’s a more detailed look at the process:
4. Cumulus Cells: These cells are part of the cumulus-oocyte complex and surround the oocyte. During fertilization, sperm must penetrate this layer of cumulus cells to reach the corona radiata and eventually the zona pellucida.
5. Corona Radiata: This is a layer of granulosa cells directly adjacent to the zona pellucida. Sperm must pass through the corona radiata to access the zona pellucida.
6. Zona Pellucida: This is the glycoprotein layer surrounding the oocyte. After passing through the corona radiata, sperm must penetrate the zona pellucida to reach and fertilize the oocyte.So, in the process of fertilization, sperm must navigate through the cumulus cells, penetrate the corona radiata, and then breach the zona pellucida to achieve fertilization.
7. Penetration of the Corona Radiata: Sperm initially penetrate through the outer layer of cells called the corona radiata, which protects the egg.
8. Penetration of the Zona Pellucida: Upon reaching the egg’s surface, sperm release enzymes that help them penetrate the zona pellucida, a glycoprotein layer surrounding the egg.
9. Fusion of Sperm and Egg: Once a sperm successfully penetrates the zona pellucida and reaches the egg’s membrane, it binds to specific receptors on the egg’s surface. This triggers changes in the egg’s membrane that prevent other sperm from entering.
10. Activation of the Egg: The fusion of sperm and egg membranes leads to the activation of the egg. This activation includes changes in the egg’s membrane potential and the release of cortical granules, which modify the zona pellucida to prevent polyspermy (fertilization by more than one sperm).
11. Formation of the Zygote: The genetic material of the sperm (23 chromosomes) and the egg (23 chromosomes) combine, forming a single-cell zygote with 46 chromosomes. This zygote represents the beginning of a new genetically unique individual.
12. Implantation: The zygote undergoes cell division as it travels down the fallopian tube towards the uterus. By the time it reaches the uterus, it has become a ball of cells called a blastocyst. The blastocyst then implants into the uterine lining (endometrium), where it continues to develop.

In summary, fertilization involves the intricate process of sperm reaching and penetrating the egg, resulting in the fusion of genetic material and the formation of a zygote. This zygote then undergoes further development to eventually form a fetus and initiate pregnancy.

Fertilization phase 1:

PHASE 1: PENETRATION OF CORONA RADIATA
•Out of the about 300 to 500 spermatozoa that reach the site of fertilization, only one fertilizes the egg by passing through the corona radiata.
Phase 2; PHASE 2: ACROSOMAL REACTION & PENETRATION OF ZONA PELLUCIDA
•occurs after binding to the zona pellucida

•induced by zona proteins (ZP3): This is why a horse sperm can’t fertilize a human egg ,cuz of these proteins

•release the enzymes: acrosin, hyaluronidase, & neuraminidase: These are enzymes that play crucial roles in sperm penetration and fertilization:

1. Acrosin: This enzyme is a type of protease found in the acrosome of sperm. It helps digest the zona pellucida, allowing the sperm to penetrate and reach the oocyte. Acrosin is essential for the acrosome reaction, which is the release of enzymes that facilitate sperm entry into the egg.
2. Hyaluronidase: This enzyme is also present in the acrosome. It breaks down hyaluronic acid, a component of the extracellular matrix in the cumulus cell layer surrounding the oocyte. By degrading hyaluronic acid, hyaluronidase helps sperm navigate through the cumulus cells to reach the corona radiata and zona pellucida.
3. Neuraminidase: This enzyme helps to remove sialic acid residues from glycoproteins and glycolipids on the surface of the oocyte. This process aids in the sperm-oocyte binding and fusion by modifying the interactions between the sperm and the zona pellucida.

All three enzymes contribute to the successful fertilization process by facilitating sperm penetration through various protective layers surrounding the oocyte.

•enzymes digest the zona pellucida

•cause perforations in the acrosome

Certainly! When considering the layers of the ovarian follicle from the outside in (moving toward the oocyte), the order is as follows:

1. Theca Externa:
   
   • Outermost layer: This is the outermost layer of the follicle. It consists of connective tissue and smooth muscle cells, providing structural support to the follicle.
2. Theca Interna:
   
   • Just inside the theca externa: This layer is highly vascularized and responsible for producing androgens, which are then converted to estrogens by the granulosa cells.
3. Granulosa Cells:
   
   • Inner layer around the oocyte: These cells surround the oocyte and are involved in nurturing and supporting its development. Within the granulosa cells:
     
     • Cumulus Oophorus: A cluster of granulosa cells that anchor the oocyte within the follicle.
     • Corona Radiata: The innermost layer of granulosa cells that directly surround the oocyte and are closely associated with it.
4. Zona Pellucida:
   
   • Directly surrounding the oocyte: A glycoprotein layer that encapsulates the oocyte and plays a key role in the fertilization process.
5. Oocyte:
   
   • Central structure: The oocyte itself is at the very center of these layers.

• Theca Externa (outermost)
• Theca Interna
• Granulosa Cells (including cumulus oophorus and corona radiata)
• Zona Pellucida
• Oocyte (innermost)

This is the correct order when moving from the outermost layer inward to the oocyte.

Question 17

What is the zona reaction and what is it’s importance
What is the perivitelline space

Answer 17

ZONA REACTION

•Change in the properties of the zona pellucida.
•Prevent polyspermy.

The zona reaction, also known as the cortical reaction or zona reaction, is a crucial process that occurs during fertilization in mammals, including humans. Here’s an explanation of what it involves:

1. Context: The zona reaction happens after a sperm cell successfully penetrates through the layers surrounding the egg, specifically the corona radiata and the zona pellucida.
2. Trigger: When the sperm reaches the zona pellucida (a glycoprotein layer surrounding the egg), it releases enzymes that help it penetrate this layer to reach the egg’s membrane.
3. Process: Once a sperm successfully binds to and penetrates the zona pellucida, it triggers a series of biochemical reactions within the egg. These reactions lead to the cortical reaction:
   • Cortical Granule Release: The egg’s cortical granules, which are small secretory vesicles located just beneath the egg’s plasma membrane, undergo exocytosis. This release is triggered by the increase in intracellular calcium ions (Ca²⁺) caused by the sperm binding and penetrating the egg.
   • Function: The cortical granules release their contents into the perivitelline space (the space between the egg plasma membrane and the zona pellucida). These released substances modify the zona pellucida, making it impermeable to other sperm cells. This process is essential to prevent polyspermy, which is the fertilization of the egg by more than one sperm cell.
4. Outcome: The modifications of the zona pellucida by the cortical reaction ensure that only one sperm can successfully fertilize the egg. It also triggers changes in the egg’s membrane potential and metabolism, initiating the processes that lead to the formation of a diploid zygote.

In summary, the zona reaction refers to the series of events where the egg’s cortical granules release their contents upon fertilization, modifying the zona pellucida to prevent polyspermy and initiating the activation of the egg for subsequent development. It is a critical mechanism to ensure successful fertilization and subsequent embryonic development.

Question 18

Another explanation for fertilization

Answer 18

Fertilization is a multi-phase process that involves the union of a sperm cell and an egg cell (ovum) to form a zygote. This process can be broken down into several key phases:

1. Sperm Capacitation
2. Sperm-Egg Recognition and Binding
3. Acrosome Reaction
4. Penetration of the Zona Pellucida
5. Fusion of Sperm and Egg Membranes
6. Cortical Reaction and Prevention of Polyspermy
7. Completion of Meiosis II by the Egg
8. Fusion of Genetic Material and Formation of the Zygote

• Definition: A process that occurs in the female reproductive tract where sperm undergo biochemical changes to become capable of fertilizing an egg.
• Changes: Removal of glycoproteins and cholesterol from the sperm membrane increases motility and prepares the sperm for the acrosome reaction.

• Chemoattraction: The ovum releases chemoattractants that guide capacitated sperm towards it.
• Binding: Sperm bind to specific receptors on the zona pellucida, the glycoprotein layer surrounding the egg.

• Triggered by Binding: Binding to the zona pellucida induces the acrosome reaction, where the acrosome (a cap-like structure on the sperm head) releases enzymes.
• Purpose: These enzymes help digest the zona pellucida, allowing the sperm to penetrate this outer layer.

• Enzymatic Digestion: The enzymes from the acrosome reaction digest a pathway through the zona pellucida.
• Sperm Movement: The sperm moves through this pathway to reach the perivitelline space (the space between the zona pellucida and the egg membrane).

• Binding: The sperm binds to the egg membrane (oolemma) via specific receptors.
• Membrane Fusion: The membranes of the sperm and egg fuse, allowing the sperm’s nucleus and other cellular components to enter the egg cytoplasm.

• Cortical Granule Release: Fusion triggers the release of cortical granules from the egg into the perivitelline space.
• Zona Reaction: The enzymes from cortical granules alter the zona pellucida, making it impermeable to additional sperm (polyspermy prevention).
• Membrane Block: Changes in the egg membrane also prevent further sperm from binding.

• Meiosis Resumption: The entry of the sperm triggers the secondary oocyte to complete meiosis II.
• Formation of the Ootid and Second Polar Body: This results in the formation of an ootid (which quickly becomes a mature ovum) and a second polar body.

• Pronuclei Formation: The sperm’s nucleus decondenses to form the male pronucleus, and the egg’s nucleus forms the female pronucleus.
• Pronuclear Fusion: The male and female pronuclei move towards each other and fuse, combining their genetic material.
• Zygote Formation: The fusion results in a single diploid nucleus, marking the formation of a zygote.

The fertilization process involves multiple complex and coordinated steps, ensuring the successful union of the sperm and egg to form

Question 19

Why is it that no animal can get a woman pregnant except the sperm of a human male.
When does the second meiotic division that occurs in oogenesis happen? Before or after fertilization?

Answer 19

How does the ovum prevent polyspermy?
When one sperm successful penetrates the zona pellucida, There is release of calcium that hardens the zona pellucida prevent any other sperm from entering

ZP3 receptors do not recognize or allow any other type of sperm to fertilize the human egg so no animal can get a woman pregnant except the sperm of a human male.

Note: it occurs after fertilization not before

Question 20

What is the pervitelline space and why is it important

Answer 20

I believe there might be a misunderstanding in your question. Let’s clarify the terms related to the structures surrounding the egg during fertilization:

1. Corona Radiata: This is a layer of cells surrounding the egg. It is the outermost layer of cells that adheres to the zona pellucida.
2. Zona Pellucida: This is a glycoprotein layer that surrounds the egg plasma membrane. It lies beneath the corona radiata and plays a crucial role in sperm-egg interactions.
3. Perivitelline Space: This is the space between the zona pellucida and the egg plasma membrane. It is also sometimes referred to as the perivitelline cavity or perivitelline membrane.

During fertilization:

• Sperm first penetrate the corona radiata, which is the layer of follicle cells surrounding the egg.
• After penetrating the corona radiata, sperm then interact with and penetrate the zona pellucida, which is a thick glycoprotein layer surrounding the egg.
• Once a sperm penetrates the zona pellucida and reaches the egg plasma membrane, it binds to specific receptors on the egg’s surface.
• The fusion of the sperm cell membrane with the egg cell membrane occurs, and the sperm nucleus enters the egg.
• After fertilization, the egg undergoes a cortical reaction. This reaction involves the release of enzymes that thicken the zona pellucida and prevent other sperm from fertilizing the egg.

Therefore, the perivitelline space or cavity is the space between the zona pellucida and the egg plasma membrane. It is important during fertilization as it is where various interactions and biochemical changes occur that lead to the fusion of sperm and egg, and subsequent fertilization processes.

Question 21

What is the pervitelline space and why is it important

Answer 21

I believe there might be a misunderstanding in your question. Let’s clarify the terms related to the structures surrounding the egg during fertilization:

1. Corona Radiata: This is a layer of cells surrounding the egg. It is the outermost layer of cells that adheres to the zona pellucida.
2. Zona Pellucida: This is a glycoprotein layer that surrounds the egg plasma membrane. It lies beneath the corona radiata and plays a crucial role in sperm-egg interactions.
3. Perivitelline Space: This is the space between the zona pellucida and the egg plasma membrane. It is also sometimes referred to as the perivitelline cavity or perivitelline membrane.

During fertilization:

• Sperm first penetrate the corona radiata, which is the layer of follicle cells surrounding the egg.
• After penetrating the corona radiata, sperm then interact with and penetrate the zona pellucida, which is a thick glycoprotein layer surrounding the egg.
• Once a sperm penetrates the zona pellucida and reaches the egg plasma membrane, it binds to specific receptors on the egg’s surface.
• The fusion of the sperm cell membrane with the egg cell membrane occurs, and the sperm nucleus enters the egg.
• After fertilization, the egg undergoes a cortical reaction. This reaction involves the release of enzymes that thicken the zona pellucida and prevent other sperm from fertilizing the egg.

Therefore, the perivitelline space or cavity is the space between the zona pellucida and the egg plasma membrane. It is important during fertilization as it is where various interactions and biochemical changes occur that lead to the fusion of sperm and egg, and subsequent fertilization processes.

Question 22

How many days from fertilization does it take for the cyst to implant into the womb
Explain the process that occurs after fertilization till the implantation
How many days after fertilization must the zygote split for you to get DCDA
While the cells mass move towards the uterus, it keeps dividing. This causes the cell size to increase while cell number increase. True or false
If the zygote splits at the morula stage, what twins are formed?
At blastocyst stage but before implantation, what twins are formed?
After implantation, what twins are formed ?
What is hatching ?
Which layer of the trophoblast forms the placenta?

Answer 22

So the zygote must split within the 1-5 days after fertilization cuz 1-3 is morula and 4-5 is early blastocyst

Cells of inner cell mass are pluripotent. Blastocyst( trophoblast and inner cell mass called embryoblast)
Trophoblast differentiates into cytotrophoblast and syncytiotrophoblast

Morula—16 cells(still has zona pellucida)
Blastocyst-32 cells(sheds zona pellucida when it’s about to implant into the uterine wall )

False!! The cell size doesn’t change. Just the cell number increases. Never forget this !!!
Outer cell mass becomes trophoblast and inner cell mass becomes embryoblast

Embryoblast becomes the baby’s body parts. If it separates into two, it forms identical twins

7 days apart period from fertilization to the blasts forming and implanting in the womb.

Start afresh:
So the blastocyst has three layers(outer layer: trophoblast and inner cell mass:embryoblast)
If the ball of cells divide at the morula stage,it’ll form diachorionic diamniotic twins, if it divides at the blastocyst stage too right before the trophoblast differentiates into cyto trophoblast(inner layer of the trophoblast and syncytiotrophoblast, it’ll also form Diachorionic Diamniotic twins. This is because the syncytiotrophoblast gives rise to the outer layer that invades the uterine lining and gives rise to the chorion. So if there are two syncytiotrophoblast, there’ll be two chorions.
It starts the differentiation after day 7 of fertilization
So the final ball that implants into the uterine lining comprises of the syncytiotrophoblast(which invades the lining),the cytotrophoblast(which becomes like the outer lining),the embryoblast and then the blastocyst cavity.

M After the formation of the zygote, several critical processes occur as it progresses towards implantation in the uterus. Here’s a step-by-step explanation:

1. Zygote Formation: The zygote is formed immediately after fertilization when the genetic material of the sperm (23 chromosomes) combines with that of the egg (23 chromosomes), resulting in a single diploid cell with 46 chromosomes.
2. Cleavage: Once formed, the zygote undergoes rapid mitotic cell divisions called cleavage. During cleavage, the zygote divides into smaller and smaller cells called blastomeres. (First a 2 cell blastula then a four cell blastula before the morula)
   These divisions do not increase the overall size of the embryo but increase the number of cells, forming a solid ball of cells called a morula.
3. Formation of the Morula: The morula is a compact ball of cells resulting from several rounds of cleavage divisions of the zygote. It consists of around 16 to 32 cells. It uses day 1 to 3 after fertilization to form.
4. early Blastocyst Formation: Around 4-5 days after fertilization, the morula undergoes further cell divisions and begins to differentiate into two distinct cell types:
   
   • Inner Cell Mass (ICM): This group of cells will develop into the embryo itself.
   • Trophoblast: These cells will form the outer layer of the blastocyst and play a crucial role in implantation.
5. Blastocyst Hatching: By about day 5-6 after fertilization, the blastocyst undergoes a process called hatching. During hatching, the blastocyst breaks out of the zona pellucida, the glycoprotein shell that has surrounded it since fertilization.
6. Initiation of Implantation: After hatching, the blastocyst is now ready for implantation into the endometrium (lining of the uterus). This process is tightly regulated and involves:
   
   • Apposition: The blastocyst comes into close contact with the endometrial lining.
   • Adhesion: Trophoblast cells adhere to the endometrial cells, establishing initial contact.
   • Invasion: Trophoblast cells then invade the endometrial lining, allowing the blastocyst to become firmly embedded in the endometrium.
   • Decidualization: The endometrial cells undergo changes (decidualization) to support the implanting blastocyst and subsequent embryonic development.
7. Establishment of Placenta: After successful implantation, trophoblast cells continue to proliferate and differentiate. They form the placenta, an organ that connects the developing fetus to the uterine wall to provide nutrients, gas exchange, and waste elimination.

In summary, after the formation of the zygote, the embryo undergoes cleavage, morula formation, blastocyst formation, hatching from the zona pellucida, and implantation into the uterine wall. These processes are essential for the embryo’s continued development and the establishment of a successful pregnancy.

Let’s clarify the stages of early embryonic development:

1. Zygote: After fertilization, the sperm and egg nuclei fuse to form a single-celled zygote. This marks the beginning of embryonic development.
2. Cleavage: The zygote undergoes a series of rapid mitotic divisions called cleavage. These divisions produce smaller cells called blastomeres.
3. Morula: After several rounds of cleavage, the embryo becomes a solid ball of cells known as the morula, typically around 16-32 cells.
4. Blastula: The morula continues to divide, and a cavity called the blastocoel forms within the ball of cells, transforming it into a blastula. In mammals, this stage is often referred to as the blastocyst, which consists of an inner cell mass (which will form the embryo) and an outer cell layer (the trophoblast, which will form part of the placenta).

To summarize the stages:

1. Zygote: Single cell formed by fertilization.
2. Cleavage: Series of divisions producing blastomeres.
3. Morula: Solid ball of cells formed after several cleavage divisions.
4. Blastula (Blastocyst in mammals): Structure with a fluid-filled cavity (blastocoel) that forms after the morula stage.

So, you are correct in that cleavage produces blastomeres, the morula forms, and then the blastula (or blastocyst in mammals) is formed before further differentiation.

It seems there’s a bit of confusion between the normal process of implantation and the case of identical (monozygotic) twinning. Let’s clarify:

1. Zygote: After fertilization, the zygote undergoes cleavage divisions as it travels down the fallopian tube.
2. Morula: By the time the embryo reaches the uterus, it has formed a morula.
3. Blastocyst: The morula develops into a blastocyst, which consists of an inner cell mass (embryoblast) and an outer cell layer (trophoblast).
4. Implantation: The blastocyst implants into the uterine wall, and the trophoblast differentiates into:
   
   • Cytotrophoblast: Inner cellular layer.
   • Syncytiotrophoblast: Outer layer that invades the endometrium.

In the case of identical twins, the single zygote splits into two separate embryos. The timing of this split affects the type of twinning:

1. Early Split (0-4 days after fertilization): If the split occurs at the early morula stage, before the formation of the blastocyst, each twin will have its own chorion and amnion (dichorionic-diamniotic twins).
2. Intermediate Split (4-8 days after fertilization): If the split occurs after the formation of the blastocyst but before implantation, the twins will share the same chorion but have separate amnions (monochorionic-diamniotic twins).
3. Late Split (8-12 days after fertilization): If the split occurs after implantation has begun, the twins will share both the chorion and the amnion (monochorionic-monoamniotic twins).

In the normal process of implantation, the differentiation of the trophoblast into the cytotrophoblast and syncytiotrophoblast occurs as a single embryo implants into the uterine wall. In the case of identical twinning, if the split occurs before or during early stages of implantation, the trophoblast may need to adjust to accommodate the developing twin embryos.

If the split occurs during the intermediate stage (4-8 days after fertilization), the resulting twins will share the same chorion but have separate amnions. Here’s why:

1. Formation of Chorion: The chorion begins to form soon after the blastocyst stage. If the split happens after the blastocyst stage, but before the complete implantation, the trophoblast layer, which forms the chorion, is already established.
2. Intermediate Split: When the zygote splits during this period, the two embryos each form their own amniotic sacs but are enclosed within the same chorionic sac because the chorion has already started to form and is shared by the developing embryos.
3. Shared Chorion: Since the split occurs after the formation of the chorion, both embryos are surrounded by a single chorionic sac, leading to a monochorionic arrangement.
4. Separate Amnions: The amniotic cavities, which form from the inner cell mass, are established after the chorion. Thus, each twin develops its own amniotic sac, resulting in a monochorionic-diamniotic (one chorion, two amnions) setup.

In summary, the chorion is shared because the trophoblast, which forms the chorion, has already differentiated and is in place when the split occurs, whereas the amniotic cavities form from the inner cell mass, allowing each embryo to have its own amnion.

The placenta is formed primarily from the syncytiotrophoblast layer of the trophoblast.

The trophoblast, which is the outer cell layer of the blastocyst, differentiates into two distinct layers during early pregnancy:

1. Cytotrophoblast:
   
   • This is the inner layer of the trophoblast consisting of mononuclear cells.
   • It serves as a source of new cells that will differentiate into the syncytiotrophoblast.
2. Syncytiotrophoblast:
   
   • This is the outer layer of the trophoblast.
   • It consists of a multinucleated, continuous cell layer without distinct cell boundaries.
   • It is responsible for the invasion into the maternal endometrium and the formation of the primary structure of the placenta.
   • The syncytiotrophoblast is involved in the secretion of hormones like human chorionic gonadotropin (hCG), which is crucial for maintaining pregnancy.

• The syncytiotrophoblast layer invades the uterine lining, establishing the placenta and creating the interface between maternal and fetal blood supplies.
• As the pregnancy progresses, the placenta develops into a highly specialized organ for nutrient and gas exchange between the mother and the fetus.

Therefore, the syncytiotrophoblast is the key layer of the trophoblast that contributes to the formation of the placenta.

Question 23

State the things that affect spermatogenesis
What helps in cooling down and regulating temp of scrotum
What suppresses the maturation of female genitalia

Answer 23

Things that affect spermatogenesis:
High temperatures
Leydig cells produce testosterone and help the sperms to mature
Dartos (not ductus) and cremasteric muscles that are located in the scrotum also helps to regulate temperature of scrotum: when the weather is cold,your scrotum shrivels up and when it’s hot,it hangs out.
Skin of scrotum also has sweat glands that are responsible for producing sweat which helps in regulating temp by cooling down the temperature
What helps in cooling down and regulating the temperature of the scrotum.
Warm blood from testicular artery supplying blood to the testes and pampiniform plexus draining the testis

Sertoli cells produce mollerian inhibiting factor that suppressed the maturation of female genitalia and gives way to maturation of male genitalia
Androgen binding proteins concentrates testosterone produced by leydig cells

Semineferous tubules are clustered in lobules and contain the

Question 24

What are the types of twins

Answer 24

Monozygotic
Dizygotic

Monozygotic: Monochorionic monoamniotic
Monochorionic diamniotic
Dichorionic diamniotic
Siamese or conjoined twins

Dizygotic:
Dichorionic diamniotic

1. Monochorionic-Monoamniotic Twins (MCMA)
2. Monochorionic-Diamniotic Twins (MCDA):
   
   • Chorionic:
3. Dichorionic-Diamniotic Twins (DCDA):

Monozygotic twins, also known as identical twins, are formed when a single fertilized egg (zygote) splits into two embryos. The types of monozygotic twins are classified based on the timing and extent of the embryo splitting, which determines their chorionic (outer membrane) and amniotic (inner membrane) arrangements:

1. Monochorionic-Monoamniotic (MCMA) Twins:
   
   • Chorionic Arrangement: MCMA twins share a single chorionic sac (outer membrane).
   • Amniotic Arrangement: They also share a single amniotic sac (inner membrane).
   • Formation: MCMA twins result from the zygote splitting late, usually between days 8 and 12 after fertilization.
   • Characteristics: This is the rarest type of monozygotic twins and carries the highest risk of complications due to shared amniotic sac, such as cord entanglement.
2. Monochorionic-Diamniotic (MCDA) Twins:
   
   • Chorionic Arrangement: MCDA twins share a single chorionic sac (outer membrane).
   • Amniotic Arrangement: They have separate amniotic sacs (inner membranes).
   • Formation: MCDA twins result from the zygote splitting early, within the first 4 days after fertilization.
   • Characteristics: These twins share a placenta but have separate amniotic sacs, which reduces some risks compared to MCMA twins.
3. Dichorionic-Diamniotic (DCDA) Twins:
   
   • Chorionic Arrangement: DCDA twins have separate chorionic sacs (outer membranes).
   • Amniotic Arrangement: They also have separate amniotic sacs (inner membranes).
   • Formation: DCDA twins result from the splitting of the zygote into two
   • Characteristics: These twins are genetically distinct and have their own placenta, chorionic sacs, and amniotic sacs, making them similar to typical dizygotic (fraternal) twins.

Each type of monozygotic twin has unique implications for pregnancy management and potential complications. Understanding these classifications helps healthcare providers provide appropriate care and anticipate any specific challenges that may arise during prenatal care and childbirth.

Question 25

What type of twins share one chorion and one amnion?

Answer 25

Monochorionic-Monoamniotic Twins (MCMA)**:(these are conjoined. The normal twins always have either a chorion separately or an amnion separately or share one amnion but have different chorions or shares one chorion but have different amnions. Info reaching me is that we have MCMA that aren’t siamese)
- Chorionic: Monochorionic twins share a single chorionic sac, meaning they have a single outer fetal membrane surrounding both embryos.
- Amniotic: Monoamniotic twins share a single amniotic sac, meaning they are contained within a single inner fetal membrane.
- Characteristics: MCMA twins are very rare and occur when a single fertilized egg splits later than usual, resulting in two embryos sharing both the chorionic and amniotic sacs. This condition is associated with higher risks, such as umbilical cord entanglement.

Question 26

What type of twins share one chorion but have different amnions

Answer 26

Monochorionic-Diamniotic Twins (MCDA)**:
They have one chorion because the zygote didn’t split into two early enough for the something something to make provision for two babies. So it makes one chorion for provision for one baby but two babies are there with their own amnions
- Chorionic: Monochorionic twins share a single chorionic sac but have separate amniotic sacs.
- Amniotic: Diamniotic twins have separate amniotic sacs, meaning each twin is contained within its own inner fetal membrane.
- Characteristics: MCDA twins are formed when a single fertilized egg splits early in development, resulting in two embryos sharing the same outer membrane (chorion) but having separate inner membranes (amnion). They are more common than MCMA twins but still carry risks related to sharing a placenta.

Question 27

What type of twins have different chorions and have different amnions

Answer 27

Dichorionic-Diamniotic Twins (DCDA)**:
- Chorionic: Dichorionic twins have separate chorionic sacs, meaning each twin has its own outer fetal membrane.
- Amniotic: Diamniotic twins have separate amniotic sacs, meaning each twin is contained within its own inner fetal membrane.
- Characteristics: DCDA twins result from the fertilization of two separate eggs by two separate sperm cells. They are the most common type of twins and are typically less risky compared to monochorionic twins because they have separate placental circulations.

Understanding whether twins are monochorionic or dichorionic, and whether they are monoamniotic or diamniotic, is crucial for prenatal care and management. It helps healthcare providers anticipate and address potential complications such as twin-to-twin transfusion syndrome (TTTS) in monochorionic twins, which can affect their shared placenta and blood circulation.

Question 28

Difference between chorion and amnion

Answer 28

The terms “chorionic” and “amniotic” refer to specific membranes that surround and support the developing embryo or fetus during pregnancy. Here’s what each term means in the context of prenatal development:

1. Chorionic:
   
   • The chorion is one of the fetal membranes that develops from the outermost layer of cells of the embryo. It plays several important roles:
     
     • Fetal-Maternal Interface: The chorion forms the outermost layer of the fetal portion of the placenta. It interfaces with the mother’s uterine tissue to facilitate nutrient exchange and waste removal.
     • Hormone Production: The chorion is responsible for producing important hormones during early pregnancy, such as human chorionic gonadotropin (hCG), which supports the development of the pregnancy.
     • Chorionic Villi: These finger-like projections extend into the uterine lining and play a crucial role in the exchange of gases, nutrients, and waste products between the maternal and fetal circulations.
2. Amniotic:
   
   • The amnion is another fetal membrane that forms inside the chorion and surrounds the embryo or fetus. It serves several functions:
     
     • Protection: The amniotic fluid within the amniotic sac provides a cushioning and protective environment for the developing embryo or fetus, protecting it from external trauma.
     • Temperature Regulation: The amniotic fluid helps maintain a stable temperature around the embryo or fetus.
     • Growth and Movement: It allows for fetal movement and helps prevent adherence of fetal skin to the amniotic sac.

Why “Chorionic” and “Amniotic” Terms Are Used:
- These terms are used because they specifically describe the structures and functions of the membranes that are crucial for the development and well-being of the embryo or fetus during pregnancy.
- Understanding the chorionic and amniotic structures helps healthcare providers monitor fetal development, assess potential complications (such as placental issues or membrane ruptures), and plan appropriate prenatal care and delivery strategies.
- Additionally, these membranes are important in differentiating various types of twins based on their chorionic and amniotic arrangements (e.g., monochorionic-diamniotic, dichorionic-diamniotic), which have implications for prenatal care and management.

In summary, “chorionic” and “amniotic” are terms used to describe specific fetal membranes that play essential roles in supporting and protecting the developing embryo or fetus throughout pregnancy. Each membrane has distinct functions related to fetal-maternal exchange, hormone production, protection, and growth facilitation.

Question 29

Twins that are dichorionic diamniotic share a placenta true or false

Answer 29

False. They have two different placentas because they have two chorions (the chorion forms the base for the placenta)

Question 30

Explain the difference between dichorionic diamniotic twins under dizygotic twins and then dichorionic diamniotic under monozygotic twins

Answer 30

The key difference lies in how each type of dichorionic-diamniotic (DCDA) twins originates:

1. Dichorionic-Diamniotic Twins in Dizygotic Twins (Fraternal Twins):
   
   • Origin: Dizygotic twins result from the fertilization of two separate eggs (ova) by two separate sperm cells.
   • Zygosity: These twins are genetically distinct from each other, just like any other siblings born from different pregnancies.
   • Chorionic and Amniotic Sac Arrangement: Each twin has its own chorionic sac (outer membrane) and its own amniotic sac (inner membrane).
   • Placental Arrangement: They may share a placenta if the two implantation sites are close enough, but each twin has its own distinct chorionic sac and amniotic sac.
2. Dichorionic-Diamniotic Twins in Monozygotic Twins (Identical Twins):
   
   • Origin: Monozygotic twins result from a single fertilized egg (zygote) that splits into two embryos.
   • Zygosity: These twins are genetically identical, sharing 100% of their DNA.
   • Chorionic and Amniotic Sac Arrangement: This type of arrangement typically occurs when the zygote splits very early, within the first few days after fertilization. Each embryo develops its own chorionic sac and its own amniotic sac.
   • Placental Arrangement: Monozygotic dichorionic-diamniotic twins have two separate placentas, each attached to its own chorionic sac.

Summary:
- Dizygotic (Fraternal) Dichorionic-Diamniotic Twins: Two separate eggs are fertilized by two separate sperm cells, resulting in twins who are genetically distinct and have their own chorionic and amniotic sacs. They may or may not share a placenta.

• Monozygotic (Identical) Dichorionic-Diamniotic Twins: A single fertilized egg splits into two embryos early in development. Despite being genetically identical, each twin has its own chorionic and amniotic sacs. They each have their own placenta as well, attached to their respective chorionic sacs.

Understanding these distinctions is crucial in prenatal care and management, as each type of twin has unique implications for monitoring, potential complications, and delivery planning.

Question 31

Where does spermatogenesis happen in the male body?
Each testis is divided into how many lobules?
What temperature is optimum for sperm
Production

Answer 31

The testis

It Requires a temperature two degrees Celsius below body temperature for optimum sperm production
Each testis is divided into 250 lobules

1. Lobules in Each Testis: Each testis is divided into about 250 to 300 lobules. Each lobule contains seminiferous tubules where sperm production occurs.
2. Optimum Temperature for Sperm Production: The optimum temperature for sperm production is approximately 2-3°C below the body’s core temperature, which is around 34-35°C (93.2-95°F). 36.6-37.5This is typically achieved within the scrotum, which maintains a temperature slightly cooler than the internal body temperature.

Question 32

What do the seminiferous tubules contain
Another name for sustentacular cells are?
Another name for interstitial cells are?

Answer 32

So these tubules is where spermatogenesis occurs. Seminiferous tubules contain the cells and structures necessary for sperm production (spermatogenesis). These tubules are the functional units within the testes where spermatogenesis occurs. Here’s what you can find within seminiferous tubules:

1. Spermatogonia: These are undifferentiated stem cells that reside along the inner lining of the seminiferous tubules. They undergo mitosis to replenish themselves and also give rise to sperm cells.
2. Sertoli cells (Sustentacular cells): These are supportive cells that extend from the basal lamina to the lumen of the seminiferous tubules. Sertoli cells provide physical and nutritional support to developing sperm cells. They also play a role in the process of spermatogenesis, including the phagocytosis of residual bodies and the secretion of inhibin.
3. Leydig cells (Interstitial cells): These are located in the interstitial tissue surrounding the seminiferous tubules. Leydig cells produce and secrete testosterone, which is important for the development and maintenance of male reproductive tissues and secondary sexual characteristics.
4. Sperm cells (spermatozoa): These are the mature male gametes produced through spermatogenesis. They develop from spermatogonia through several stages (spermatocytes, spermatids) within the seminiferous tubules.

In summary, seminiferous tubules contain spermatogonia, Sertoli cells, Leydig cells, and sperm cells—all of which are essential for the process of spermatogenesis and the production of sperm.

Question 33

What’s the function of the epidiymis
Explain the process that occurs from the sperm cell getting to the urethra

Answer 33

Temporarily stores sperm and creates an avenue for the sperm to mature . Has three parts(body head and tail) the tail is connected to the vas deferens.

The pathway for a sperm cell from its production in the seminiferous tubules of the testes to its exit from the body through the urethra is as follows:

1. Seminiferous Tubules: Sperm cells are produced through spermatogenesis within the seminiferous tubules of the testes.
2. Rete Testis: From the seminiferous tubules, sperm cells move into the rete testis, a network of tubules in the mediastinum of the testis.
3. Efferent Ductules: From the rete testis, sperm cells pass through the efferent ductules, which transport them from the testis to the epididymis.
4. Epididymis: The epididymis is a coiled tube located on the posterior surface of each testis. Sperm cells mature and gain motility as they pass through the epididymis.
5. Vas Deferens (Ductus Deferens): From the epididymis, sperm cells move into the vas deferens, a muscular tube that ascends through the spermatic cord into the pelvic cavity.
6. Ejaculatory Duct: The vas deferens joins with the seminal vesicle(this produces seminal fluid and prostaglandin E) to form the ejaculatory duct within the prostate gland.
7. Prostatic Urethra: The ejaculatory duct empties into the prostatic urethra, which passes through the prostate gland.
8. Membranous Urethra: From the prostatic urethra, the semen (which now contains sperm) enters the membranous urethra, which is surrounded by the external urethral sphincter.
9. Penile (Spongy) Urethra: Finally, the sperm-containing semen travels through the penile (spongy) urethra, which runs through the length of the penis.
10. External Urethral Orifice: The sperm-containing semen exits the body through the external urethral orifice, located at the tip of the penis during ejaculation.

This pathway ensures that sperm cells undergo maturation and gain the ability to move (motility) as they travel from the testes to the exterior of the body through the urethra during ejaculation.

Question 34

Which cells produce mullerian jnhubiting factor

Leydig or Sertoli

Answer 34

Sertoli cells produce Müllerian inhibiting factor (MIF), also known as anti-Müllerian hormone (AMH). MIF plays a crucial role in male sexual differentiation by causing the regression of the Müllerian ducts during embryonic development, which prevents the formation of female reproductive structures.

Question 35

Main muscles that make up penis.

Remember that most of the questions come from the embryology part of the reproductive system in anatomy(thats the spermatogenesis and Oogenesis,fertilization and Capacitation and cell division)

Answer 35

Main muscles that make up penis:
Corpus cavernosum(plural is cavernosa)
Corpus spongiosum
Then maybe bulbospongiusum and ischiocavernous muscles

The main structures associated with the penis are:

1. Corpus Cavernosum (plural: corpora cavernosa): These are two cylindrical structures that run along the dorsal side of the penis. They are responsible for the rigidity of the penis during erection.
2. Corpus Spongiosum: This is a single cylindrical structure that surrounds the urethra and extends from the base of the penis to the glans (head). It helps keep the urethra open during erection and contributes to the penis’s overall shape.

Additional muscles involved in the function and support of the penis include:

3. Bulbospongiosus Muscle: This muscle surrounds the bulb of the penis and assists in the expulsion of urine and semen. It also contributes to the maintenance of penile erection.
4. Ischiocavernosus Muscle: This muscle covers the crura (the root) of the penis and helps to maintain erection by compressing the crura and restricting venous outflow.

These structures work together to support the function and mechanics of the penis, especially during erection and ejaculation.

Question 36

Basic anatomy involves the structure and organization of body systems

Da Vinci is one of the people that started dissection in the medieval times

• [ ] Know the Several organs in the human body that serve functions in two or more systems;

1. Pancreas:
   
   • Digestive System: It produces digestive enzymes (amylase, lipase, proteases) that are secreted into the small intestine to aid in digestion.
   • Endocrine System: It produces hormones such as insulin and glucagon, which regulate blood sugar levels.
2. Liver:
   
   • Digestive System: It produces bile, which helps break down fats in the digestive process.
   • Circulatory System: It processes nutrients absorbed from the digestive tract and detoxifies harmful substances in the blood.
3. Thymus:
   
   • Immune System: It is involved in the maturation of T-cells, a type of white blood cell critical for immune response.
   • Endocrine System: It secretes hormones like thymosin that stimulate the development of T-cells.
4. Gonads (Testes/Ovaries):
   
   • Reproductive System: They produce gametes (sperm in males, eggs in females).
   • Endocrine System: They secrete sex hormones, such as testosterone in males and estrogen and progesterone in females.
5. Hypothalamus:
   
   • Nervous System: It regulates many autonomic functions like hunger, thirst, and body temperature.
   • Endocrine System: It controls the pituitary gland and regulates the release of various hormones.
6. Kidneys:
   
   • Urinary System: They filter blood to remove waste and produce urine.
   • Endocrine System: They secrete hormones like erythropoietin (which stimulates red blood cell production) and renin (which helps regulate blood pressure).

These organs highlight the body’s interconnected nature, where one organ can play crucial roles in multiple physiological processes.

In the digestive system, the pancreas performs several crucial functions:

1. Production of Digestive Enzymes: The pancreas produces digestive enzymes that are secreted into the small intestine. These enzymes include:
   
   • Amylase: Breaks down carbohydrates into simple sugars.
   • Lipase: Breaks down fats into fatty acids and glycerol.
   • Proteases (such as trypsin and chymotrypsin): Break down proteins into peptides and amino acids.
2. Production of Bicarbonate: The pancreas secretes bicarbonate ions into the small intestine. This neutralizes the acidic chyme (partially digested food) coming from the stomach, creating an optimal pH environment for the enzymes to function effectively.

These functions are essential for the digestion and absorption of nutrients from food, helping to break down complex molecules into forms that can be absorbed into the bloodstream.

• [ ] Parts of the stomach
• [ ] Types of small intestine. Know the flow of food in a systematic and orderly fashion till it gets to the rectum
• [ ] To appendix to ascending colon,transverse,descending,sigmoid colon, rectum and anus
  Endodermal and ectodermal side of body.

Oral cavity:
Uvula Divides orifice into two equal parts
Area around the teeth outward is the vestibule
This is different from the oral cavity

• [ ] Names of salivary glands-parotid (serous and si below ear),submandibular(mucous), sublingual (this is below the tongue and is sero-mucous)
• [ ] Function of tongue-taste where it has taste buds and papillae
• [ ] Number of adult teeth
• [ ] Types of teeth from front to sideways-incisors,canines,premolar,molars
• [ ] Innervation of tongue: succus terminalis divided tongue into posterior and anterior. Why is it called valate in tongue. Fungiform,valate,folliate papillae
• [ ]
• [ ] Divisions of the gut-oseophagus past stomach to the 1/3rd duodenum. The line that divides the duodenum for the foregut and midgut is?? Ampulla of Vater or major duodenal duct (comprises of common bile duct which is from the pancreas) The line that divides the large intestine for the midgut and hindgut is??
• [ ] Components of each type of gut and the blood supply

Ascending and anterior 2/3rd I’d transverse is in midgut
Last 1/3rd of Transverse and rest of colon is hindgut

Parts of the large intestine

• [ ] Cardiac region and cardiac notch of stomach

Folding of small intestine to increase surface to volume ratio

Appendix to ascending to transverse to descending to rectum to colon

Gametogenesis:

Sperm looks like tadpole
Granulosa or follicular cells give nutrients to the egg cell
Antrum or antral follicle is a space near the egg cell
Granulosa cells near the egg itself are (form circumferential arrangement )called corona radiata cells
Cumulus oophorius which are granulosa cells that hold the egg cell

Oogonium is for one
Oogonia is for more

Meiosis is a reduction division. Homologous chromosome separates here in meiosis I

Second mieotic unfinished state is what is ovulated.

Then it finishes when a sperm comes to fertilize it

Cells close the skin of the testes is called spermatogonium
As they grow, the move deep into the testes
Younger sperm are outside and mature sperm are more inside the testes
Spermiogeneniss is a morphological change that helps early spermatids to develop and be ready for action

Ootid undergoes differentiation to form ovum after fertilization.

Men have stem cells which are able to regenerate spermatogonia

B spermatocytes form spermatogonia

Primordial follicles to primary oocyte
Pre antral follicle

Cells that help in spermatogenesis
- [ ] Sertoli: fibroblasts growth factors for development and maturation of sperm. Has Sertoli sertoli junctions or blood testis barrier that shield the naive spermatogonia from hazardous environment in the blood
- [ ] Peritubular cell or myoid cells-these cells surround the Semineferous tubules and produce colony stimulating factor . This CSF maintain and regulate spermatogonia stem cells. The testis is considered an immune-privileged site, meaning it requires regulation of immune responses to protect developing sperm cells. CSFs modulate the immune environment by influencing immune cells in the testis, preventing inflammatory responses that could disrupt spermatogenesis.
- [ ] Leydig cells-testosterone

Fertilization: occurs in two phases
Phase 1- penetration of corona radiata
Phase 2- penetration of zona pellucida

Answer 36

Here’s a detailed breakdown of the topics you’re interested in:

• Cardia: The region where the esophagus connects to the stomach.
• Fundus: The upper curved part of the stomach.
• Body (Corpus): The central, largest part of the stomach.
• Pylorus: The lower part of the stomach that connects to the duodenum through the pyloric sphincter.
• Pyloric Sphincter: Regulates the passage of food from the stomach to the duodenum.

• Duodenum: The first part, where chyme from the stomach mixes with bile and pancreatic juices.
• Jejunum: The middle section, responsible for the majority of nutrient absorption.
• Ileum: The final part, which continues nutrient absorption and connects to the large intestine at the ileocecal valve.

• Oral Cavity → Pharynx → Esophagus → Stomach → Duodenum → Jejunum → Ileum → Cecum → Ascending Colon → Transverse Colon → Descending Colon → Sigmoid Colon → Rectum → Anus.

• Endodermal: The inner germ layer that forms the gastrointestinal tract, liver, pancreas, and lungs.
• Ectodermal: The outer germ layer that forms the skin and nervous system.

• Uvula: A small, fleshy extension at the back of the soft palate that helps close off the nasal passages during swallowing. Uvula: The uvula is a small, fleshy extension at the back of the soft palate. It helps to close off the nasopharynx during swallowing to prevent food and liquids from entering the nasal cavity. However, it does not divide the oral cavity into two equal parts.
• Vestibule: The space between the gums and the inner lining of the lips and cheeks.

• Parotid Glands: Located below and in front of the ear, primarily serous secretion.
• Submandibular Glands: Located beneath the lower jaw, producing mixed serous and mucous secretions.
• Sublingual Glands: Located under the tongue, producing mostly mucous secretions.

• Taste: The tongue has taste buds on its papillae (fungiform, vallate, and foliate) for taste perception.

• 32: Including 8 incisors, 4 canines, 8 premolars, and 12 molars (including wisdom teeth).

• Incisors: Front teeth for cutting.
• Canines: Pointed teeth for tearing.
• Premolars: Flat-topped teeth for grinding.
• Molars: Larger teeth at the back for grinding and crushing.

• Anterior 2/3: Taste is primarily via the facial nerve (CN VII), while general sensation is through the mandibular nerve (CN V3).
• Posterior 1/3: Taste and general sensation are primarily via the glossopharyngeal nerve (CN IX).

• Foregut: From the esophagus to the first part of the duodenum (up to the ampulla of Vater).
• Midgut: From the second part of the duodenum to approximately two-thirds of the transverse colon.
• Hindgut: From the last third of the transverse colon to the rectum.

• Foregut: Includes the esophagus, stomach, and part of the duodenum. Blood supply from the celiac trunk.
• Midgut: Includes the remaining duodenum, jejunum, ileum, cecum, and appendix. Blood supply from the superior mesenteric artery.
• Hindgut: Includes the rest of the colon (descending, sigmoid) and rectum. Blood supply from the inferior mesenteric artery.

• Cardiac Region: The area of the stomach adjacent to the esophagus.
• Cardiac Notch: The angular indentation on the stomach’s upper-left side where the esophagus meets the stomach.

• Villi: Tiny, finger-like projections that increase surface area for absorption.
• Microvilli: Even smaller projections on the surface of enterocytes (intestinal lining cells) that further increase surface area.

• Appendix: Attached to the cecum.
• Ascending Colon: Moves up the right side of the abdomen.
• Transverse Colon: Crosses the abdomen from right to left.
• Descending Colon: Moves down the left side.
• Sigmoid Colon: S-shaped segment before the rectum.
• Rectum: The final segment before the anus.

• Sperm: Has a tadpole-like shape with a head, midpiece, and tail for motility.
• Granulosa Cells: Provide nutrients and support to the developing oocyte.
• Antrum (or Antral Follicle): The fluid-filled space surrounding the oocyte in a mature follicle.
• Corona Radiata: A layer of granulosa cells directly surrounding the oocyte, forming a protective barrier.
• Cumulus Oophorus: A cluster of granulosa cells that support the oocyte and are attached to the oocyte in the antral follicle.

Feel free to ask for more details on any of these topics!

Here’s a detailed explanation addressing your queries:

• Cardiac Region: This is the part of the stomach adjacent to the esophagus. It is located just below the gastroesophageal junction where the esophagus meets the stomach.
• Cardiac Notch: This is the angular indentation or notch on the upper-left side of the stomach where the esophagus transitions into the stomach. It is located near the cardiac region and helps form the boundary between the esophagus and the stomach.

• The antrum (or pyloric antrum) is the lower portion of the stomach that is situated between the body of the stomach and the pyloric canal. It is responsible for grinding and mixing the stomach contents with gastric juices. The antrum plays a crucial role in the regulation of gastric emptying into the duodenum.

• Appendix: The appendix is a small, tube-like structure attached to the cecum, which is the first part of the large intestine. In the digestive flow, the sequence is:
  
  • Cecum → Appendix → Ascending Colon.

• Oral Cavity: The oral cavity includes the lips, cheeks, gums, teeth, tongue, and the roof and floor of the mouth. It’s divided into the vestibule (space between the teeth and the inner lips/cheeks) and the oral cavity proper (the space within the teeth and gums).

• Function of the Tongue:
  
  • Taste: Houses taste buds for detecting flavors.
  • Mastication: Aids in chewing and manipulating food.
  • Swallowing: Helps in pushing food towards the pharynx for swallowing.
  • Articulation: Assists in forming sounds for speech.
• Types of Papillae:
  
  • Fungiform Papillae: Mushroom-shaped and scattered over the surface of the tongue, primarily involved in taste.
  • Foliate Papillae: Found on the lateral edges of the tongue, involved in taste, more prominent in some animals.
  • Vallate (Circumvallate) Papillae: Larger, dome-shaped structures arranged in a V pattern at the back of the tongue, containing numerous taste buds.

• The line dividing the large intestine into midgut and hindgut regions is approximately at the left colic (splenic) flexure. This anatomical landmark helps differentiate between the midgut (up to the right colic flexure) and the hindgut.

• When asked which part of the esophagus meets the stomach, the correct answer is the cardiac region. The cardiac notch is a feature of the anatomy but not the specific point of junction.

Certainly! Here’s a clear distinction between the vestibule and the oral cavity:

• Definition: The oral cavity is the space inside the mouth, including everything inside the lips and cheeks.
• Components: It includes:
  
  • Teeth: For mastication (chewing).
  • Gums (Gingiva): The tissues surrounding the teeth.
  • Tongue: Involved in taste, chewing, and swallowing.
  • Hard Palate: The bony part of the roof of the mouth.
  • Soft Palate: The soft part at the back of the roof of the mouth.
  • Floor of the Mouth: The area beneath the tongue.
  • Uvula: The small, fleshy extension at the back of the soft palate.

• Definition: The vestibule is a specific area within the oral cavity, but it is distinct from the rest of the oral cavity.
• Location: It is the space between the teeth and the inner lining of the lips and cheeks.
• Components: It includes:
  
  • Buccal Mucosa: The lining of the inner cheeks.
  • Labial Mucosa: The lining of the inner surface of the lips.
  • Gingiva: The part of the gum around the teeth.

• Oral Cavity: Refers to the entire mouth space, including both the vestibule and the rest of the interior parts like the tongue, gums, and palate.
• Vestibule: A specific part of the oral cavity, located between the teeth and the inner lips/cheeks, essentially acting as the outermost section of the oral cavity.

The vestibule is a smaller, more specific area within the larger oral cavity.

When puberty hits, the primary oocyte finishes the meiosis I and this results in two haploid cells.

The secondary oocyte contains more cytoplasm than the first polar body.
Secondary oocyte is released during ovulation.
Second polar body is associated with the ovum not the ootid

Here are five medium-difficulty MCQs on the interphase part of the cell cycle:

1. Which of the following processes occurs during the G2 phase of the cell cycle?
   
   • A) DNA synthesis
   • B) Chromosome condensation
   • C) Organelle duplication and protein synthesis for mitosis
   • D) Cytokinesis
     Answer: C) Organelle duplication and protein synthesis for mitosis
2. The cell checks for proper DNA replication and repairs damage during which checkpoint of interphase?
   
   • A) G1/S checkpoint
   • B) S/G2 checkpoint
   • C) G2/M checkpoint
   • D) Spindle assembly checkpoint
     Answer: C) G2/M checkpoint
3. Which phase of interphase is the longest, during which the cell grows and carries out normal metabolic activities?
   
   • A) G1 phase
   • B) S phase
   • C) G2 phase
   • D) M phase
     Answer: A) G1 phase
4. Which molecule is most likely to regulate the transition from G1 to S phase in the cell cycle?
   
   • A) Cyclin D
   • B) Cyclin E
   • C) Cyclin B
   • D) Cyclin A
     Answer: B) Cyclin E
5. During interphase, when does the cell duplicate its centrosomes?
   
   • A) G1 phase
   • B) S phase
   • C) G2 phase
   • D) M phase
     Answer: B) S phase

In question 2: “The cell checks for proper DNA replication and repairs damage during which checkpoint of interphase?”, the possible answers are:

• A) G1/S checkpoint:
  The G1/S checkpoint occurs before the cell enters the S phase. At this checkpoint, the cell ensures it has sufficient nutrients, proper cell size, and no DNA damage. If everything is in order, the cell commits to DNA replication. However, this checkpoint does not focus on checking the accuracy of DNA replication, so it’s not the correct answer for this question.
• B) S/G2 checkpoint:
  While there isn’t a formal S/G2 checkpoint, there is constant surveillance of DNA integrity during the S phase as replication proceeds. However, the critical checking for errors after DNA replication and before mitosis happens later in the G2/M checkpoint, making this option less precise.
• C) G2/M checkpoint:
  The G2/M checkpoint occurs after the S phase and ensures that DNA has been fully and accurately replicated before the cell proceeds to mitosis. This checkpoint also repairs any DNA damage that might have occurred during replication. This is the correct answer for the question, as it directly addresses the checking of DNA replication and repair before mitosis.
• D) Spindle assembly checkpoint:
  The spindle assembly checkpoint occurs during mitosis, not interphase. It ensures that chromosomes are properly attached to the spindle fibers before the cell divides. Since this checkpoint occurs during mitosis and not interphase, it is not relevant to the question.

Correct answer:
C) G2/M checkpoint - This is the checkpoint where the cell checks for DNA replication errors and makes necessary repairs before entering mitosis.

Question 37

Anatomy last class

in primary oocyte, metaphase I starts
true or false??
false.
cuz it’s arrested in prophase I so it doesnt even get to metaphase I

secondary oocytes are ovulated in metaphase II cuz that’s where they are arrested.

glenoid cavity: ball and socket joints specifically the humerus and the scapula area. the glenoid cavity is where the humerus fits into the scapula

which part of the body that th joints are found ?
know the names of joints. example Is joint at the wrist area ?
gliding joint at the wrist

face: two groups of muscle for mastication and muscles for facial expressions

muscles for smiling, for mouth
muscles around eye

sartorius muscle or Tailors muscle or seat belt muscle : iliac crest to knee

what is the longest bone in the body?
femur in thigh region

shortest bone in body??

head of femur articulates what type of fossa ?
obturator foramen
(questions like this)

differences between cervical and other vertebrae and the number of vertebrae for each

atlas and axis plus the other vertebrae : which doesnt have body or centrum or which will carry the least weight

divisions of PNS and CNS

VENTRAL CARRIES MOTOR
DORSAL IS SENSORY
Which passes the back and which passes the front.

Ventricles in brain- CSF is stored here

cerebral aqueduct - if blocked, CSF cannot flow so it’ll cause hydrocephalus

which chamber of heart receives deoxygenated blood ?
which chamber receives systematic flow of blood ? right atrium.

stratum basalae or stratum germinatum

stratum spinosum has projections or spines that’s why it’s called spinosum

stratum granulosum cuz it contains granules

stratum leucidium
stratum cornea

keratin are dead cells so they an withstand harsh environment

what are lacunae and canaliculi in bones??
lacunae is where osteocytes live or are located. it’s a depression or space
canaliculi: channels through which substances can flow

what is osteon?

bulksman canal and haversian canal- which goes horizontal and which goes vertical or laterally or transverse ??
they both carry blood vessels

tooth:
what is the tooth made up of??
enamel,dentine

hardest substance in the body?
softest substance in body?

types of nerve cells: bipolar -located in only two places(retina and olfactory muscosa)

pseudounipolar location

cranial nerves and where they innervate

which bone doesn’t have a joint??

which bone is called funny bone?

articulations of clavicle - medial and lateral articulations
medial is sternum
laterally is??

parts of sternum - manubrium,body,xiphoid process

when you place your hand on your hips, what bone is your hand resting on ?
the iliac crest

type of joint between parietal and occipital bone?
sutural joint

difference between a ligament and a tendon

joint that allows only for flexion and extension: hinge joint

muscle used for kissing: something something oris

pelvic girdle
iliotibial tract

the questions are vvry basic
like from shs so learn shs stuff if possible
let chat gpt give you easy questions to answer
not difficult cuz difficult won’tcome
it’s the easy to medium level in All the systems taught in class

meninges :
which of the 3 is the thickest?
dura meninges cuz it’s the outermost

where Is CSF located in the meninges ?
which of the meninges CAnt you detach from any part of the CNS??
PIA MATTER

Synapses are near dendrites and near cell bodies and these are ffound d in Gray matter

number if spinal nerves in each vertebrae

at what level of vertebrae will you imagine the end of the spinal cord in an adult?
L something

where do the afferent neurons terminate finally in the brain?
??? is it cerebral hemispheres or hypothalamus or medulla??

sutures in skull

Question 38

About the skin
Parts of the skin and layers of the epidermis
Which layer of the epidermis covers thick skin?
Which layer is the part where stem cells divide to produce new keratinocytes??

Answer 38

The epidermis is The outermost layer of the skin, composed of stratified squamous epithelium

The stratum basale is The deepest layer, consisting of a single row of columnar or cuboidal cells that divide and produce new keratinocytes. It includes melanocytes (pigment-producing cells) and Merkel cells (sensory receptors). . Aged cells are at the top and new ones are below or at the base.

Thick Skin: Typically found on areas like the palms of the hands and the soles of the feet.
• Hair Presence: Thick skin does not have hair follicles. It is characterized by a thicker epidermis and lacks hair, sebaceous glands, and arrector pili muscles, which are present in thinner skin.

1. Epidermis: The outermost layer, providing a protective barrier.
   
   • Layers of the epidermis (from deepest to most superficial):
     
     • Stratum basale (basal layer): Contains stem cells that divide to produce new keratinocytes. Another name for the stratum basale is the stratum germinativum. This name reflects its role in the constant generation of new keratinocytes through cell division. These new cells move upwards through the layers of the epidermis to eventually replace the outermost cells.
     • Stratum spinosum (prickle cell layer): Provides strength and flexibility, with cells starting to flatten.has projections or spines that’s why it’s called spinosum l. The stratum spinosum, also known as the prickle cell layer, gets its name because the cells in this layer have spiny projections or desmosomal connections when viewed under a microscope. These spines are visible due to the way the cells shrink during tissue preparation while the desmosomes (which connect cells) remain intact, giving them a “spiny” appearance.
     • Stratum granulosum (granular layer): Cells become more flattened and accumulate keratohyalin granules. Called the granular later cuz it contains granules
     • Stratum lucidum (clear layer): Found only in thick skin, like palms and soles. Stratum lucidum is not found in thin skin:
       • The stratum lucidum is a thin, clear layer of dead keratinocytes, and it is only present in thick skin. Thick skin is found on areas of the body that are subject to friction and pressure, such as the palms of the hands and soles of the feet.
       • In thin skin, like the skin covering most of the body, this layer is absent because thin skin doesn’t need the extra protection provided by the stratum lucidum. Thin skin only has the other four layers (stratum basale, stratum spinosum, stratum granulosum, and stratum corneum).
     • Stratum corneum (horny layer): Consists of dead, flat keratinized cells that form the skin’s outermost protective barrier. Keratin are dead cells so they can withstand pressure from outside.
       In anatomy, the outermost layer of organs are thicker than the other layers to withstand pressure
2. Dermis: Located beneath the epidermis, contains connective tissue, blood vessels, nerves, hair follicles, and glands.
   
   • Divided into two layers:
     
     • Papillary dermis: The upper part, with loose connective tissue and capillaries.
     • Reticular dermis: The deeper part, containing thicker collagen fibers for strength and elasticity.
3. Hypodermis (subcutaneous layer): The deepest layer, made of fat and connective tissue that provides insulation and cushioning.

Subcutaneous layer (hypodermis):
• You’re right again! The subcutaneous layer (hypodermis) is not technically part of the skin. It lies beneath the skin and is primarily made up of fat and connective tissue.
• Although it’s often mentioned when discussing skin anatomy due to its close association with the dermis, the hypodermis is not considered one of the layers of the skin itself

Question 39

Hardest substance in human body is?
State the parts of the tooth
What is the dental formula for adult humans?
What about human babies?
State the four types of papillae on the tongue and where they are more prominent

Answer 39

Taste buds contain gustatory cells that detect the five basic tastes: sweet, sour, salty, bitter, and umami.

Front: Fungiform papillae.
• Back: Circumvallate (vallate) papillae.
• Sides: Foliate papillae.
• Middle/General surface: Filiform papillae (without taste buds).

1. Fungiform papillae:
   
   • Located mostly on the anterior part of the tongue.
   • Mushroom-shaped and scattered across the surface.
   • Contain taste buds that detect various tastes (sweet, sour, salty, etc.).
2. Circumvallate (Vallate) papillae:
   
   • Found at the back of the tongue, arranged in a V-shape near the sulcus terminalis.
   • Large and round, with taste buds on the sides.
   • Particularly sensitive to bitter tastes.
3. Foliate papillae:
   
   • Located on the sides of the tongue, near the back.
   • Have taste buds that detect taste, especially in early childhood.
4. Filiform papillae:
   
   • The most numerous and found all over the tongue, but do not contain taste buds.
   • Their primary function is to provide friction to help with the movement of food and cleaning the mouth.

So the four types are: fungiform, circumvallate (vallate), foliate, and filiform.

The tooth is made up of several distinct layers and structures:

1. Enamel:
   
   • The outermost, hardest substance in the human body.
   • It covers the crown of the tooth and is composed mostly of hydroxyapatite, a crystalline calcium phosphate.
   • Its hardness protects the tooth from wear and tear during chewing.
2. Dentin:
   
   • Lies beneath the enamel and makes up the bulk of the tooth.
   • It is softer than enamel but still harder than bone. Dentin is living tissue, and it is sensitive to temperature and pain due to the presence of microscopic tubules that connect to the nerve of the tooth.
3. Pulp:
   
   • The innermost part of the tooth, containing nerves and blood vessels.
   • This is the softest part of the tooth, responsible for supplying nutrients and sensation to the tooth.
4. Cementum:
   
   • A thin layer that covers the tooth’s root and helps anchor the tooth in the jawbone by attaching to fibers in the periodontal ligament. Cementum covers root of tooth while enamel covers the crown or the most visible part of the tooth
5. Periodontal Ligament:
   
   • Connects the tooth to the surrounding alveolar bone (jawbone) and provides cushioning during chewing.

• Hardest substance: Enamel (covering the teeth).
• Softest substance: Pulp (within the tooth).

• Gingiva (gums): The soft tissue surrounding the teeth that helps protect the root

Gingiva (Gums): The soft tissue that surrounds and supports the teeth.
• Alveolar bone: The part of the jaw that houses the tooth sockets.
• Crown: The visible part of the tooth.
• Root: The part of the tooth that anchors it into the jawbone.
• Incisors, Canines, Premolars, Molars: Types of teeth, each with specific functions for cutting, tearing, and grinding food.

1. Incisors:
   
   • Located at the front of the mouth (4 in the upper jaw and 4 in the lower jaw).
   • Function: Used for cutting and biting food.
2. Canines (also called cuspids):
   
   • Sharp, pointed teeth located next to the incisors (2 in the upper jaw and 2 in the lower jaw).
   • Function: Designed for tearing food, especially meat.
3. Premolars (also called bicuspids):
   
   • Located behind the canines (4 in the upper jaw and 4 in the lower jaw).
   • Function: Used for crushing and grinding food.
4. Molars:
   
   • The large, flat teeth at the back of the mouth (6 in the upper jaw and 6 in the lower jaw, including the wisdom teeth).
   • Function: Primarily used for grinding and chewing food into smaller pieces.

The human dental formula for permanent teeth

Types of Teeth and Their Functions in Humans:

1.	Incisors:
•	Location: Front of the mouth (four on top, four on bottom).
•	Function: Used for cutting or biting food into smaller pieces.
2.	Canines (Cuspids):
•	Location: Next to the incisors (two on top, two on bottom).
•	Function: Designed for tearing and holding food. They are the sharpest teeth with a pointed shape.
3.	Premolars (Bicuspids):
•	Location: Behind the canines (four on top, four on bottom).
•	Function: Used for crushing and grinding food. They have flat surfaces with ridges for grinding.
4.	Molars:
•	Location: Furthest back in the mouth (six on top, six on bottom).
•	Function: Grind and crush food. They are the largest teeth with broad, flat surfaces for heavy-duty grinding.

Dental Formula for Humans:

The dental formula represents the number and types of teeth in one half of the mouth. Since teeth are symmetrical, it applies to both the upper and lower halves of the mouth.

•	Adult humans:
•	Formula: 2-1-2-3 (Incisors-Canines-Premolars-Molars)
•	This means for one half of the mouth (upper or lower):
•	2 incisors
•	1 canine
•	2 premolars
•	3 molars
•	Multiply by 2 for the full set of teeth (upper and lower), giving a total of 32 teeth.
•	Children (Primary/Deciduous teeth):
•	Formula: 2-1-2 (Incisors-Canines-Molars)
•	This means children have a total of 20 teeth

Children don’t have premolars because premolars are part of the permanent dentition, which develops as the jaw grows and can accommodate more teeth. In children, the primary (baby) teeth consist of incisors, canines, and molars, but no premolars

Here’s a quick summary of the tongue’s innervation:

• General sensation (touch, pain, etc.): Lingual nerve (branch of CN V3, Trigeminal nerve).
• Taste sensation: Chorda tympani (branch of CN VII, Facial nerve).

• General sensation and taste: Glossopharyngeal nerve (CN IX).

• Hypoglossal nerve (CN XII) innervates all tongue muscles except one.
• Palatoglossus muscle is innervated by the Vagus nerve (CN X).

• Sulcus terminalis divides the tongue into the anterior two-thirds (innervated by CN V3 and CN VII) and the posterior one-third (innervated by CN IX).

Question 40

Yes, the Haversian system is also known as the osteon. It is the fundamental structural unit of compact (cortical) bone. Each osteon consists of concentric layers of calcified matrix (lamellae) surrounding a central canal (Haversian canal) that contains blood vessels and nerves. This system helps supply nutrients and remove waste products from the bone tissue.

Cumulus oophorius is the stalk that holds the ovum.

Fertilization: occurs in two phases
Phase 1- penetration of corona radiata
Phase 2- penetration of zona pellucida

• Lower Mandible: The mandible is the lower jawbone, and it is the only movable bone of the skull.
• Upper Mandible (Maxilla): The maxilla refers to the upper jaw, which forms part of the skull and holds the upper teeth. Unlike the mandible, the maxilla is fixed and does not move.

1. Sphenoid Bone: A complex, butterfly-shaped bone located in the middle of the skull, forming part of the base of the cranium and the sides of the skull. It helps form the orbits of the eyes.
2. Frontal Bone: The bone that forms the forehead and the upper part of the eye sockets (orbits).
3. Occipital Bone: The bone at the back and base of the skull, containing the foramen magnum, where the spinal cord passes through to connect to the brain.

Other important bones of the skull include:
- Parietal Bones: Two bones that form the sides and roof of the skull.
- Temporal Bones: Located on the sides of the skull, around the ear region.
- Ethmoid Bone: A small, delicate bone located between the eyes, forming part of the nasal cavity and the orbits.

Axial skeleton is skull,rib cage,vertebrae

The ulna is medial, and the radius is lateral when in the anatomical position (with the palms facing forward).

Biggest fossa-obturator foramen which is located in the pelvis

Bones that make up the axial and appendicular skeleton :

The obturator foramen is the largest foramen in the body. It is located in the pelvis, formed by the pubic and ischial bones, and allows the passage of nerves and blood vessels.

The axial skeleton consists of 80 bones, forming the central axis of the body, and includes:
1. Skull: 22 bones (cranial and facial bones).
2. Hyoid bone: 1 bone in the neck, supporting the tongue.
3. Vertebral Column: 26 bones (including cervical, thoracic, lumbar vertebrae, sacrum, and coccyx).
4. Thoracic Cage:
- Ribs: 24 bones (12 pairs).
- Sternum: 1 bone.

The appendicular skeleton consists of 126 bones, which include the bones of the limbs and the girdles (shoulder and pelvic) that connect them to the axial skeleton.
1. Pectoral (Shoulder) Girdle:
- Clavicle: 2 bones.
- Scapula: 2 bones.

2. Upper Limbs:
   
   • Humerus: 2 bones.
   • Ulna: 2 bones.
   • Radius: 2 bones.
   • Carpals (Wrist bones): 16 bones.
   • Metacarpals (Palm bones): 10 bones.
   • Phalanges (Finger bones): 28 bones.
3. Pelvic Girdle:
   
   • Hip bones (Ilium, Ischium, Pubis): 2 bones.
4. Lower Limbs:
   
   • Femur: 2 bones.
   • Patella: 2 bones.
   • Tibia: 2 bones.
   • Fibula: 2 bones.
   • Tarsals (Ankle bones): 14 bones.
   • Metatarsals (Foot bones): 10 bones.
   • Phalanges (Toe bones): 28 bones.

Osteoblasts are young bone cells. These are dynamic and very active
. Differentiate into osteocytes and can’t differentiate any further once they become osteocytes.
Osteocytes are mature bone cells.
Osteoclasts resorb worn out bones.

Chrondro is cartilage

Clavicle and scapula (appendicular or axial???)

The clavicle (collarbone) and scapula (shoulder blade) are both part of the appendicular skeleton, not the axial skeleton. The appendicular skeleton consists of the bones of the limbs and girdles (shoulder and pelvic), while the axial skeleton includes the skull, vertebral column, and rib cage.

Ossification can occur in the skull of a baby.

The anterior fontanelle is diamond-shaped, while the posterior fontanelle is triangular-shaped.

C1-7
T1-12
L1-5
S1-5

Atlas and axis
Which has odontoid process?

The axis (C2 vertebra) has the odontoid process (also known as the dens), which is a bony projection that allows the atlas (C1 vertebra) to pivot and rotate the head. The atlas does not have an odontoid process but rather a ring-like structure that supports the skull.

Joints:
Fossa- depression in bones
Foramen- hollow space

Intercalated discs join one fiber to the other in the cardiac muscle.
Position of nucleus in muscles.

Fusiform(have tapered ends but midline is enlarged) or spindle shaped- smooth muscles

Plenty muscles in the face cuz the face has different facial Expressions

Chest muscles- pectoralis muscles major and minor

Sternocleidomastoid in neck

Seatbelt muscle on thigh-sartorious muscle
Ileotibial tract around hips -
Gluteal muscles- 3 of them

Iliotibial Tract (IT Band):

The iliotibial tract (IT band) is a thick band of connective tissue that runs along the outside of the thigh from the hip to the knee. It stabilizes the knee and assists with movements of the hip and thigh.

Gluteal Muscles (3 of Them):

1.	Gluteus Maximus: The largest and most superficial of the gluteal muscles, responsible for extending and rotating the thigh.
2.	Gluteus Medius: Located beneath the gluteus maximus, it is involved in abducting and medially rotating the thigh.
3.	Gluteus Minimus: The smallest and deepest gluteal muscle, also involved in thigh abduction and medial rotation.

Peristalsis can be controlled at a part where skeletal Muscles are. The skeletal muscles are in the upper 1/3rd of the oesophagus
.

CVS-
Types of capillaries : fenestrated (have holes in them. Seen in glomerulus of Kidney) and non fenestrated
Types of vein- large vein,medium
Sized vein and venules. Have tunica wrapped around them. Know the parts. Tunica media is composed of smooth muscles. Elastic fibers in veins or vessels
Types of artery’s -elastic artery,muscular artery,arteriole. Difference in sizes of lumen and tunicas

Another name for elastic artery is large artery
Another name for
Medium size artery is muscular artery

Right ventricle to pulmonary trunk into the lungs.

Systemic and pulmonary circulation

Capillary bed is where exchange goes on.

Smooth msucles in arteries and veins. Difference in tunica of arteries and veins.
Blood isn’t moving at high pressure so there is baxkflow of blood if the valves don’t work

Here’s a more detailed overview of the different types of blood vessels, including their structures and functions:

1. Fenestrated Capillaries:
   
   • Structure: Have pores (fenestrae) in their endothelial lining.
   • Locations: Found in areas requiring rapid exchange of small molecules, such as the glomeruli of the kidneys, intestines, and endocrine glands.
2. Non-Fenestrated Capillaries:
   
   • Structure: Have a continuous endothelial lining with no pores.
   • Locations: Found in most tissues, including muscle, skin, and the blood-brain barrier.

1. Large Veins:
   
   • Examples: Superior and inferior vena cava.
   • Structure: Have a larger lumen and more developed tunica adventitia (outer layer). Tunica media is thinner with less smooth muscle compared to arteries.
2. Medium-Sized Veins:
   
   • Examples: Femoral vein, brachial vein.
   • Structure: Have a smaller lumen compared to large veins, but still contain valves to prevent backflow. Tunica media is relatively thin, and tunica adventitia is prominent.
3. Venules:
   
   • Structure: Small veins that receive blood from capillaries. They have a very thin tunica media and tunica adventitia.

1. Elastic Arteries:
   
   • Other Name: Large arteries.
   • Examples: Aorta, pulmonary arteries.
   • Structure: Have a large lumen and a thick tunica intima, tunica media (rich in elastic fibers), and tunica adventitia. The elastic fibers allow these arteries to stretch and recoil to accommodate the high pressure of blood flow.
2. Muscular Arteries:
   
   • Other Name: Medium-sized arteries.
   • Examples: Femoral artery, radial artery.
   • Structure: Have a smaller lumen compared to elastic arteries and a thicker tunica media composed mainly of smooth muscle fibers. They regulate blood flow to specific organs and tissues by constriction and dilation.
3. Arterioles:
   
   • Structure: Smallest arteries leading to capillaries. They have a very thin tunica intima and a thin tunica media with a few layers of smooth muscle. They play a crucial role in regulating blood flow and blood pressure.

• Tunica Intima: The innermost layer, consisting of endothelial cells. It provides a smooth lining for blood flow.
• Tunica Media: The middle layer, consisting of smooth muscle and elastic fibers. It regulates the diameter of the vessel and blood pressure.
• Tunica Adventitia: The outer layer, consisting of connective tissue that provides structural support and elasticity.

• Arteries: Have more smooth muscle in the tunica media, allowing them to handle higher pressure and regulate blood flow.
• Veins: Have less smooth muscle compared to arteries and rely on valves to prevent backflow and assist with venous return to the heart.

• Function: Sites of nutrient, gas, and waste exchange between blood and tissues.

• Veins: Blood in veins is under lower pressure. Valves help prevent backflow and ensure one-way blood flow towards the heart. If valves are defective, it can lead to conditions like varicose veins.

Understanding these aspects helps in comprehending how the circulatory system functions to deliver blood efficiently throughout the body.

Conducting pathway- conducts air
Respiratory pathway does exchange

Intercostal and other muscle sim ribs and in exclamation and inhalation

Primary filtration occurs from pharynx -larynx to the trachea

Blood air barrier- pneumocyste type I cells also called alveolar cells
Alveolar lining and endothelium of capillaries

The blood-air barrier (also known as the air-blood barrier) is the thin barrier that separates the air in the alveoli from the blood in the capillaries, allowing for efficient gas exchange. It consists of the following components:

1. Type I Pneumocytes (Alveolar Type I Cells):
   
   • Description: These are thin, squamous epithelial cells that line the alveolar walls. They cover the majority of the surface area of the alveoli.
   • Function: They provide a large surface area for gas exchange and form the primary component of the blood-air barrier.
2. Alveolar Lining:
   
   • Description: The lining of the alveoli is composed of the type I pneumocytes, which create a thin surface for the diffusion of gases.
3. Endothelium of Capillaries:
   
   • Description: The endothelial cells that line the capillaries are thin and closely apposed to the type I pneumocytes. They form the inner lining of the blood vessels.

• Alveolar Epithelium: Consists of type I pneumocytes.
• Basement Membrane of Alveolar Epithelium: A thin layer of extracellular matrix that separates the alveolar epithelium from the capillary endothelium.
• Capillary Endothelium: The endothelial cells lining the capillaries.
• Basement Membrane of Capillary Endothelium: Sometimes fused with the alveolar basement membrane, further reducing the distance for gas diffusion.

This barrier is extremely thin to facilitate the rapid exchange of oxygen and carbon dioxide between the air in the alveoli and the blood in the capillaries.

Question 41

VENTRAL CARRIES MOTOR
DORSAL IS SENSORY
Which passes the back and which passes the front.

Answer 41

A mnemonic to remember the difference between the central (ventral) and dorsal roots in terms of motor and sensory functions is “SAME DAVE”:

• SAME:
  
  • Sensory: Afferent (incoming signals, towards the central nervous system)
  • Motor: Efferent (outgoing signals, away from the central nervous system)
• DAVE:
  
  • Dorsal: Afferent (sensory signals enter the spinal cord via the dorsal root)
  • Ventral: Efferent (motor signals exit the spinal cord via the ventral root)

This mnemonic helps distinguish that the dorsal root carries sensory (afferent) information, while the ventral root carries motor (efferent) information.

Afferent passes the back cuz it’s going to give info to the brain while efferent passes the front cuz it’s going to the body

Question 42

CNS:
Which part of the brain stores the CSF
What happens when the cerebral aqueduct is blocked ?
State the types of nerve cells
Which two places is the bipolar nerve cell located in?
What about the pseudounipolar neurons ?
State the 12 cranial nerves and where they innervate
where Is CSF located in the meninges?
which of the meninges CAnt you detach from any part of the CNS??

at what level of vertebrae will you imagine the end of the spinal cord in an adult?

where do the afferent neurons terminate finally in the brain? ??? is it cerebral hemispheres or hypothalamus or medulla??
What is gyri and what is sulcus

Answer 42

Ependymal cells and choroid plexus produce CSF. The ependymal cells are glial cells.
Astrocytes- blood brain barrier
Satellite cells- structural and nutritional functions

Anterior Median Fissure:
• Description: This is a deep, longitudinal groove running along the anterior midline of the spinal cord.
• Depth: It is deeper than a sulcus and serves to divide the spinal cord into symmetrical halves.
• Posterior Median Sulcus:
• Description: This is a shallower groove running along the posterior midline of the spinal cord.
• Depth: It is less deep compared to the anterior median fissure and helps to demarcate the posterior aspect of the spinal cord.

**Correct, satellite cells are found only in the peripheral nervous system (PNS). In the central nervous system (CNS), their functions are performed by astrocytes, which provide structural support, regulate the extracellular environment, and offer metabolic support to neurons.

Sutures in skull
Fight and flight.
Parasympathetic or sympathetic?? Ans is sympathetic
Spinal nerves : There are 12
pairs of cranial nerves and 31 pairs of spinal nerves.
• Cranial Nerves: These nerves arise from the brain and primarily innervate structures in the head and neck.
• Spinal Nerves: These nerves arise from the spinal cord and are categorized into 8
• ⁠and are categorized into 8
cervical, 12 thoracic, 5
lumbar, 5 sacral, and 1 coccygeal pairs.
Gray matter is butterfly shaped with a central canal and is gray cuz it’s made up of many cell bodies but few axons. So more central processes and few peripheral
White matter has more peripheral processes and less central processes.
Anterior median fissure. Deeper than sulcus
Posterior median sulcus

Afferent enter from back
Efferent are from front
Mixed nerve: cuz it’s made up of sensory and motor
Pseudo polar neuron in afferent in dorsal root ganglion
What cells produce CSF?
What are satellite cellls

Ventricles in brain- CSF is stored here

What happens when the cerebral aqueduct is blocked ? - if blocked, CSF cannot flow so it’ll cause hydrocephalus

types of nerve cells:
bipolar
-located in only two
places(retina and olfactory muscosa)
pseudounipolar location: Pseudounipolar neurons are primarily located in the sensory ganglia of the peripheral nervous system, specifically in the dorsal root ganglia (DRG) of the spinal cord and the cranial nerve ganglia

cranial nerves and where they innervate
where Is CSF located in the meninges?
which of the meninges CAnt you detach from any part of the CNS??
PIA MATTER

1. Olfactory nerve (CN I):
   
   • Function: Sense of smell.
   • Innervates: Olfactory epithelium in the nasal cavity.
2. Optic nerve (CN II):
   
   • Function: Vision.
   • Innervates: Retina of the eye.
3. Oculomotor nerve (CN III):
   
   • Function: Eye movement, pupil constriction.
   • Innervates: Most of the extrinsic eye muscles (except lateral rectus and superior oblique), as well as the muscles responsible for pupil constriction.
4. Trochlear nerve (CN IV):
   
   • Function: Eye movement.
   • Innervates: Superior oblique muscle of the eye.
5. Trigeminal nerve (CN V):
   
   • Function: Sensation to the face, chewing.
   • Innervates:
     
     • Ophthalmic (V1): Sensation from upper face (forehead, scalp, upper eyelid).
     • Maxillary (V2): Sensation from middle face (cheeks, upper lip, upper teeth).
     • Mandibular (V3): Sensation from lower face (chin, lower lip, lower teeth), and motor innervation for chewing muscles.
6. Abducens nerve (CN VI):
   
   • Function: Eye movement.
   • Innervates: Lateral rectus muscle (responsible for abducting the eye).
7. Facial nerve (CN VII):
   
   • Function: Facial expression, taste from anterior two-thirds of the tongue, salivation, and tear production.
   • Innervates: Muscles of facial expression, lacrimal glands, submandibular and sublingual salivary glands.
8. Vestibulocochlear nerve (CN VIII):
   
   • Function: Hearing and balance.
   • Innervates: Cochlea (hearing) and vestibular apparatus (balance).
9. Glossopharyngeal nerve (CN IX):
   
   • Function: Taste from the posterior one-third of the tongue, sensation from the pharynx, swallowing, and salivation.
   • Innervates: Stylopharyngeus muscle, parotid gland, and sensation from the pharynx and posterior tongue.
10. Vagus nerve (CN X):
    - Function: Parasympathetic control of the heart, lungs, digestive tract, as well as sensation from the larynx and pharynx.
    - Innervates: Muscles of the larynx, pharynx, and parasympathetic innervation to thoracic and abdominal organs.
11. Accessory nerve (CN XI):
    - Function: Shoulder and neck movement.
    - Innervates: Sternocleidomastoid and trapezius muscles.
12. Hypoglossal nerve (CN XII):
    - Function: Tongue movement.
    - Innervates: Muscles of the tongue.

• Cerebrospinal Fluid (CSF) is located in the subarachnoid space, which lies between the arachnoid mater and the pia mater. This space surrounds the brain and spinal cord, providing cushioning and protection.
  ### Meninges That Cannot Be Detached from Any Part of the CNS:- The pia mater is the innermost layer of the meninges and cannot be detached from the surface of the brain and spinal cord. It closely adheres to the contours of the CNS, following every groove and fissure.

sulci are the grooves or indentations, while gyri are the elevated ridges between those grooves.

Synapses are near dendrites and near cell bodies and these are found d in Gray matter
number if spinal nerves in each vertebrae
at what level of vertebrae will you imagine the end of the spinal cord in an adult?
L something

•	In an adult, the spinal cord typically ends at the level of the L1-L2 vertebrae. Below this level, the spinal nerves continue as the cauda equina.

Afferent Neuron Termination in the Brain:
• Afferent neurons (sensory neurons) typically terminate in the thalamus before relaying their information to the cerebral hemispheres for processing.

There are 8 cervical nerves but 7 cervical vertebrae.

The gray matter has a high density of neuronal cell bodies and dendrites, which are crucial for synaptic activity. Here’s a breakdown of why synapses are predominantly found in gray matter:

1.	Neuronal Cell Bodies: Gray matter contains the cell bodies of neurons, which are the primary sites where synaptic connections are formed. These cell bodies, along with their dendrites, engage in the reception and processing of synaptic inputs.
2.	Dendritic Arbors: The dendrites of neurons in gray matter form extensive branching networks that receive and integrate synaptic signals from other neurons. These dendrites are where most of the synaptic activity occurs.

where do the afferent neurons terminate finally in the brain? ??? is it cerebral hemispheres or hypothalamus or medulla??

Sutures in skull
Fight and flight.
Parasympathetic or sympathetic?? Ans is sympathetic
Spinal nerves : There are 12
pairs of cranial nerves and 31 pairs of spinal nerves.
• Cranial Nerves: These nerves arise from the brain and primarily innervate structures in the head and neck.
• Spinal Nerves: These nerves arise from the spinal cord and are categorized into 8
• ⁠and are categorized into 8
cervical, 12 thoracic, 5
lumbar, 5 sacral, and 1 coccygeal pairs.
Gray matter is butterfly shaped with a central canal and is gray cuz it’s made up of many cell bodies but few axons. So more central processes and few peripheral
White matter has more peripheral processes and less central processes.
Anterior median fissure. Deeper than sulcus
Posterior median sulcus

Afferent enter from back
Efferent are from front
Mixed nerve: cuz it’s made up of sensory and motor
Pseudo polar neuron in afferent in dorsal root ganglion
Here is a summary of your points about spinal nerves and spinal cord anatomy:
1. Gray Matter:
• Shape: Gray matter is butterfly-shaped or H-shaped in cross-section, with a central canal running through the middle.
Composition: It is gray due to a high concentration of
neuronal cell bodies and fewer myelinated axons.
It primarily contains cell bodies and central processes, making it involved in processing and integrating information.
2. White Matter:
• Composition: White matter surrounds the
gray matter and consists mostly of myelinated axons, which provide thewhich provide the pathways for transmitting information between different parts of the nervous system. It has more peripheral processes and fewer central processes.
3. Anterior Median Fissure:
• Description: A deep groove along the anterior (front) aspect of the spinal cord that separates the two halves of the spinal cord. It is deeper than the posterior median sulcus.
Posterior Median Sulcus:
• Description: A shallow groove along the posterior (back) aspect of the spinal cord that separates the two halves of the spinal cord.
5. Afferent and Efferent
Fibers:
• Afferent Fibers: Sensory neurons that enter the spinal cord through the dorsal (posterior) root.
• Efferent Fibers: Motor neurons that exit the spinal cord through the ventral (anterior) root.
⁠Mixed Nerve:
• Description: A spinal nerve is considered
mixed because it contains both sensory (afferent) and motor (efferent) fibers.
7. Pseudounipolar Neurons:
• Location: Found in the dorsal root ganglion.
• Description: These neurons have a single, short process that splits into two branches-one extending to the periphery and one entering the spinal cord
• -functioning as afferent (sensory) neurons.
Ependymal cells and choroid plexus produce CSF. The ependymal cells are glial cells.
Astrocytes- blood brain barrier
Satellite cells- structural and nutritional functions
Satellite cells are found in the peripheral nervous system (PNS) and have the following functions:
1. Structural Function:
Satellite cells provide structural support to the neurons in the ganglia neurons in the ganglia (clusters of neuronal cell bodies in the PNS). They help maintain the organization and integrity of the ganglia.
2. Nutritional Function: They provide metabolic and nutritional support to the neuronal cell bodies by regulating the microenvironment around the neurons. They assist in the exchange of nutrients and waste products between the neurons and the
surrounding interstitial fluid.
surrounding interstitial fluid.
These functions are crucial for the proper functioning and health of neurons in the PNS.
Correct, satellite cells are found only in the peripheral nervous system (PNS). In the central nervous system (CNS), their functions are performed by astrocytes, which provide structural support, regulate the extracellular environment, and offer metabolic support to neurons.

Question 43

Here are some important facts about the layers of the gastrointestinal tract (GIT) that you can use for question 5:

The walls of the gastrointestinal (GI) tract are composed of four primary layers that extend from the esophagus to the rectum. Each layer has a specific role in digestion, absorption, and the movement of food:

• Function: Secretion of digestive enzymes, absorption of nutrients, and protection from pathogens.
• Structure: Composed of three sub-layers:
  
  • Epithelium: Contains specialized cells for secretion and absorption.
  • Lamina propria: A layer of connective tissue housing blood vessels, lymphatics, and immune cells.
  • Muscularis mucosae: A thin layer of muscle that helps move the mucosa and facilitates digestion and absorption.
• Importance: The mucosa comes into direct contact with food and plays a critical role in the secretion of mucus and digestive juices.

• Function: Provides support to the mucosa and contains blood vessels, nerves, and lymphatics that nourish the surrounding tissues.
• Structure: A thick layer of connective tissue that supports the mucosa.
• Key Features:
  
  • Houses the submucosal nerve plexus, which regulates digestive secretions.
  • Contains blood and lymphatic vessels that transport absorbed nutrients to the rest of the body.

• Function: Responsible for peristalsis and the mechanical movement of food through the GI tract.
• Structure: Composed of two layers of smooth muscle:
  
  • Inner circular layer: Contracts to constrict the GI tract.
  • Outer longitudinal layer: Contracts to shorten the GI tract.
• Key Feature: The myenteric plexus (Auerbach’s plexus), located between these muscle layers, controls muscle contractions for digestion and peristalsis.

• Function: Protects the GI tract and reduces friction between digestive organs.
• Structure: A thin layer of connective tissue covered by simple squamous epithelium.
• Key Feature: In areas where the GI tract is within the peritoneal cavity (such as the stomach and intestines), the serosa is called the visceral peritoneum.

Each layer of the GIT contributes to the digestion and movement of food, absorption of nutrients, and protection of the body from harmful substances.

Answer 43

The stomach contains several types of specialized cells that contribute to digestion. Here are the key cells and their functions:

• Location: Fundus and body of the stomach
• Function: Secrete hydrochloric acid (HCl) and intrinsic factor.
• Role:
  
  • HCl lowers the pH of the stomach to help digest food and kill bacteria.
  • Intrinsic factor is essential for the absorption of vitamin B12 in the small intestine.

• Location: Fundus and body of the stomach
• Function: Secrete pepsinogen, the inactive form of the enzyme pepsin.
• Role:
  
  • Pepsinogen is activated to pepsin by the acidic environment (HCl), and pepsin breaks down proteins into smaller peptides.

• Location: Lining of the stomach, particularly in the neck region of gastric glands
• Function: Secrete mucus.
• Role: Mucus forms a protective layer over the stomach lining to prevent damage from stomach acid and digestive enzymes.

• Location: Antrum (lower part) of the stomach
• Function: Secrete the hormone gastrin.
• Role: Gastrin stimulates the secretion of gastric acid (HCl) by the parietal cells and promotes stomach motility (mixing and churning of food).

• Location: In the stomach lining, particularly near parietal cells
• Function: Secrete histamine.
• Role: Histamine stimulates parietal cells to secrete HCl, enhancing acid production.

• Location: Throughout the stomach and other parts of the gastrointestinal tract
• Function: Secrete somatostatin.
• Role: Somatostatin inhibits the release of gastric acid and slows down digestive processes when necessary.

• Parietal Cells: Secrete HCl and intrinsic factor (acid production and vitamin B12 absorption).
• Chief Cells: Secrete pepsinogen (protein digestion).
• Mucous Cells: Secrete mucus (protection of stomach lining).
• G Cells: Secrete gastrin (stimulates HCl production).
• ECL Cells: Secrete histamine (stimulates acid secretion).
• D Cells: Secrete somatostatin (inhibits acid and gastric activity).

These cells work together to aid digestion and protect the stomach lining from damage due to the acidic environment.

What cells in the stomach secrete intrinsic factor?

•	A) Parietal cells
•	B) Chief cells
•	C) Goblet cells
•	D) G cells Answer: A) Parietal cells Explanation: Parietal cells in the stomach secrete intrinsic factor, which is necessary for vitamin B12 absorption in the small intestine.

22. Which cells in the stomach secrete hydrochloric acid (HCl)?• A) Chief cells
    • B) Parietal cells
    • C) Goblet cells
    • D) Enteroendocrine cells
    Answer: B) Parietal cells
    Explanation: Parietal cells are responsible for secreting hydrochloric acid (HCl), which helps in breaking down food and killing pathogens.
23. Which cells in the stomach secrete pepsinogen, the inactive precursor of pepsin?• A) Parietal cells
    • B) Chief cells
    • C) G cells
    • D) Goblet cells
    Answer: B) Chief cells
    Explanation: Chief cells secrete pepsinogen, which is activated to pepsin by the acidic environment of the stomach. Pepsin is a key enzyme for protein digestion.

Which cells in the stomach secrete gastrin, a hormone that stimulates gastric acid secretion?

•	A) Chief cells
•	B) Parietal cells
•	C) G cells
•	D) Goblet cells Answer: C) G cells Explanation: G cells, located in the antrum of the stomach, secrete gastrin, which stimulates the secretion of hydrochloric acid by the parietal cells.

Question 44

Which of the following is the basic contractile unit of a muscle?

•	a) Sarcomere
•	b) Myofibril
•	c) Actin
•	d) Myosin Answer: a) Sarcomere Explanation: The sarcomere is the basic contractile unit within muscle fibers.

The sarcomere is the fundamental unit of contraction in striated muscle, specifically skeletal and cardiac muscle. It is defined as the segment between two adjacent Z-discs and contains the actin (thin) and myosin (thick) filaments.

When a muscle contracts, the myosin heads bind to actin, forming cross-bridges that pull the actin filaments toward the center of the sarcomere. This sliding filament mechanism shortens the sarcomere, resulting in muscle contraction. Each sarcomere works in unison with neighboring sarcomeres, allowing for coordinated muscle movement.

In contrast:
- Myofibrils are long, thread-like structures made up of many sarcomeres arranged end to end.
- Actin and myosin are the proteins that make up the filaments within the sarcomere but are not contractile units on their own.

Thus, the sarcomere is crucial for muscle function, making it the basic contractile unit.

What is the term for the functional unit of contraction in smooth muscle?
• a) Sarcomere
• b) Myofibril
• c) Smooth muscle fiber
• d) Dense body
Answer: d) Dense body
Explanation: In smooth muscle, the dense bodies serve a similar role to Z-discs in striated muscle, facilitating contraction.

5. What is the name of the neurotransmitter that stimulates muscle contraction?• a) Dopamine
   • b) Serotonin
   • c) Acetylcholine
   • d) Glutamate
   Answer: c) Acetylcholine
   Explanation: Acetylcholine is released at the neuromuscular junction to trigger muscle contraction.
6. Which muscle is responsible for extending the elbow joint?• a) Biceps brachii
   • b) Deltoid
   • c) Triceps brachii
   • d) Brachialis
   Answer: c) Triceps brachii
   Explanation: The triceps brachii extends the elbow joint, while the biceps brachii flexes it.
7. Which of the following muscles is part of the hamstring group?• a) Rectus femoris
   • b) Vastus lateralis
   • c) Biceps femoris
   • d) Sartorius
   Answer: c) Biceps femoris
   Explanation: The biceps femoris is part of the hamstring group located at the back of the thigh.

Answer 44

Which muscle is primarily responsible for flexing the hip joint?
• a) Gluteus maximus
• b) Iliopsoas
• c) Quadriceps femoris
• d) Hamstrings
Answer: b) Iliopsoas
Explanation: The iliopsoas, which includes the psoas major and iliacus muscles, is the main flexor of the hip joint.

Which muscle is located on the anterior side of the thigh and is responsible for extending the knee?
• a) Hamstrings
• b) Quadriceps femoris
• c) Adductors
• d) Sartorius
Answer: b) Quadriceps femoris
Explanation: The quadriceps femoris group extends the knee and is located on the anterior thigh.
9. What muscle is primarily involved in rotating the head to the opposite side?
• a) Sternocleidomastoid
• b) Scalenes
• c) Trapezius
• d) Splenius capitis
Answer: a) Sternocleidomastoid
Explanation: The sternocleidomastoid muscle allows for rotation and flexion of the head.
10. Which muscle is responsible for plantarflexion of the foot?
• a) Tibialis anterior
• b) Gastrocnemius
• c) Soleus
• d) Fibularis longus
Answer: b) Gastrocnemius
Explanation: The gastrocnemius muscle, along with the soleus, is a key muscle for plantarflexion at the ankle joint.

1. Which muscle is responsible for closing the eyelids?
   • a) Orbicularis oris
   • b) Orbicularis oculi
   • c) Zygomaticus major
   • d) Buccinator
   Answer: b) Orbicularis oculi
   Explanation: The orbicularis oculi muscle encircles the eye and is responsible for closing the eyelids.
   
   2. Which muscle elevates the eyebrows and wrinkles the forehead?
      • a) Frontalis
      • b) Temporalis
      • c) Masseter
      • d) Platysma
      Answer: a) Frontalis
      Explanation: The frontalis muscle is located in the forehead and helps raise the eyebrows and wrinkle the forehead.
   3. What is the primary action of the masseter muscle?
      • a) Depresses the mandible
      • b) Elevates the mandible
      • c) Protracts the mandible
      • d) Retracts the mandible
      Answer: b) Elevates the mandible
      Explanation: The masseter is a key muscle in chewing, primarily responsible for elevating the mandible.
   4. Which muscle is known as the “smiling muscle”?
      • a) Zygomaticus major
      • b) Risorius
      • c) Buccinator
      • d) Orbicularis oris
      Answer: a) Zygomaticus major
      Explanation: The zygomaticus major pulls the corners of the mouth upward, contributing to a smile.

Question 45

Here are more MCQs focusing on the muscles of the face and thigh:

1. Which muscle is primarily responsible for puckering the lips?
   
   • a) Zygomaticus minor
   • b) Orbicularis oris
   • c) Buccinator
   • d) Risorius
     Answer: b) Orbicularis oris
     Explanation: The orbicularis oris encircles the mouth and is responsible for puckering the lips.
2. Which muscle pulls the corner of the mouth downward?
   
   • a) Depressor anguli oris
   • b) Mentalis
   • c) Platysma
   • d) Orbicularis oculi
     Answer: a) Depressor anguli oris
     Explanation: The depressor anguli oris muscle pulls the corners of the mouth downward, creating a frown.
3. Which muscle is primarily responsible for chewing and helps compress the cheeks?
   
   • a) Buccinator
   • b) Temporalis
   • c) Masseter
   • d) Orbicularis oris
     Answer: a) Buccinator
     Explanation: The buccinator muscle compresses the cheeks and helps keep food between the teeth during chewing.
4. Which muscle elevates the mandible and assists in chewing?
   
   • a) Masseter
   • b) Platysma
   • c) Digastric
   • d) Mylohyoid
     Answer: a) Masseter
     Explanation: The masseter elevates the mandible, playing a key role in the chewing process.
5. Which muscle is responsible for the lateral movement of the jaw?
   
   • a) Temporalis
   • b) Masseter
   • c) Lateral pterygoid
   • d) Medial pterygoid
     Answer: c) Lateral pterygoid
     Explanation: The lateral pterygoid muscle facilitates lateral movements of the jaw, crucial for grinding food.

6. Which muscle is the primary extensor of the knee?
   
   • a) Hamstrings
   • b) Quadriceps femoris
   • c) Sartorius
   • d) Adductor longus
     Answer: b) Quadriceps femoris
     Explanation: The quadriceps femoris group extends the knee and is essential for activities like standing and walking.
7. Which muscle flexes the hip and is also involved in knee flexion?
   
   • a) Rectus femoris
   • b) Iliopsoas
   • c) Vastus lateralis
   • d) Gluteus maximus
     Answer: b) Iliopsoas
     Explanation: The iliopsoas is the main hip flexor and assists in bending the knee.
8. Which muscle is located on the medial side of the thigh and is responsible for adducting the thigh?
   
   • a) Gracilis
   • b) Rectus femoris
   • c) Vastus medialis
   • d) Tensor fasciae latae
     Answer: a) Gracilis
     Explanation: The gracilis muscle is a medial thigh muscle that adducts the thigh.
9. Which muscle is involved in both hip flexion and lateral rotation of the thigh?
   
   • a) Sartorius
   • b) Pectineus
   • c) Gluteus medius
   • d) Adductor brevis
     Answer: a) Sartorius
     Explanation: The sartorius muscle flexes the hip and assists in lateral rotation of the thigh.
10. Which muscle group is primarily responsible for flexing the knee?
    
    • a) Quadriceps femoris
    • b) Hamstrings
    • c) Adductors
    • d) Gluteals
      Answer: b) Hamstrings
      Explanation: The hamstrings, located on the posterior thigh, are responsible for flexing the knee.

Feel free to ask for more questions or specific areas of focus!

The muscle primarily responsible for kissing is the orbicularis oris. This muscle encircles the mouth and allows for the puckering and closing of the lips, facilitating the action of kissing. Other muscles, such as the zygomaticus major (which helps lift the corners of the mouth) and the buccinator (which compresses the cheeks), may also play a supportive role during the act.

Another name for the sartorius muscle is the “tailor’s muscle,” due to its action in crossing the legs, a position traditionally associated with tailors.

1. Platysma
   
   • Action: Tenses the skin of the neck and can pull down the lower lip and corners of the mouth, contributing to expressions of surprise or fright.
2. Mentalis
   
   • Action: Elevates and protrudes the lower lip, creating a pouting expression.
3. Zygomaticus Minor
   
   • Action: Assists in smiling by pulling the upper lip upwards and laterally.
4. Risorius
   
   • Action: Draws the corners of the mouth laterally, contributing to expressions like grinning.
5. Corrugator Supercilii
   
   • Action: Draws the eyebrows downward and medially, creating a frown or scowl.
6. Procerus
   
   • Action: Pulls down the skin between the eyebrows, contributing to a look of concern or anger.
7. Nasalis
   
   • Action: Flares the nostrils and can create a wrinkling effect on the bridge of the nose.

These muscles work together to create a wide range of facial expressions, allowing for non-verbal communication.

Answer 45

Brachialis
• Location: Underneath the biceps brachii in the anterior arm.
• Function: Primary flexor of the elbow; works alongside the biceps brachii.
9. Brachioradialis
• Location: Lateral forearm.
• Function: Flexes the elbow, especially when the forearm is in a neutral position; important for gripping actions.
10. Flexor Carpi Radialis
• Location: Anterior forearm.
• Function: Flexes and abducts the wrist; important for wrist movements.
11. Flexor Carpi Ulnaris
• Location: Anterior forearm.
• Function: Flexes and adducts the wrist; contributes to wrist stability.
12. Extensor Carpi Radialis Longus and Brevis
• Location: Posterior forearm.
• Function: Extends and abducts the wrist; important for lifting and gripping.
13. Extensor Digitorum
• Location: Posterior forearm.
• Function: Extends the fingers; essential for hand movements and grip.

Question 46

What is the main structural unit of compact bone?
• a) Osteon
• b) Trabecula
• c) Lacuna
• d) Lamella
Answer: a) Osteon
Explanation: The osteon, or Haversian system, is the fundamental functional unit of compact bone.

Question 47

Zygomatic Bone

•	Function: The zygomatic bone, commonly known as the cheekbone, contributes to the structure of the face. It helps form the orbit of the eye and provides attachment points for facial muscles, playing a role in facial expression and the movement of the jaw.

Bones that Make Up the Pelvic Girdle

The pelvic girdle is composed of:

1.	Ilium
2.	Ischium
3.	Pubis

These three bones fuse to form the hip bone (os coxae) on each side.

Bone You Put Your Hands on When Placing Them on Your Hips

When you put your hands on your hips, you are resting them on the ilium, specifically on the iliac crest.

Parts of the Sternum

The sternum consists of three main parts:

1.	Manubrium - the upper portion.
2.	Body (Gladiolus) - the middle and longest part.
3.	Xiphoid Process - the small, pointed lower portion.

Number of Vertebrae for Each Type

1.	Cervical Vertebrae: 7 (C1 to C7)
•	Characteristics: Smallest vertebrae, have transverse foramina, allow for head and neck movement.
2.	Thoracic Vertebrae: 12 (T1 to T12)
•	Characteristics: Larger than cervical, articulate with ribs, provide attachment points for the rib cage.
3.	Lumbar Vertebrae: 5 (L1 to L5)
•	Characteristics: Largest and strongest, designed to bear weight, have larger bodies and shorter spinous processes.
4.	Sacral Vertebrae: 5 (fused into one sacrum)
•	Characteristics: Fused vertebrae that form a single bone, connects the spine to the pelvis.
5.	Coccygeal Vertebrae: 4 (usually fused into one coccyx)
•	Characteristics: Smallest vertebrae, form the tailbone.

Common Differences for Each Type of Vertebrae

•	Cervical: Small size, transverse foramina, bifid spinous processes (C2 to C6).
•	Thoracic: Medium size, long spinous processes that point downward, articulates with ribs.
•	Lumbar: Large size, thick bodies, short and blunt spinous processes for muscle attachment.
•	Sacral: Fused, forms a triangular shape, provides strength and stability to the pelvis.
•	Coccygeal: Fused, small and rudimentary, forms the tailbone

Which joint connects the humerus to the scapula?
• a) Elbow joint
• b) Shoulder joint
• c) Wrist joint
• d) Sternoclavicular joint
Answer: b) Shoulder joint
Explanation: The shoulder joint connects the humerus to the scapula and allows for arm mobility.

What is the shortest bone in the body?
• Answer: The shortest bone in the body is the stapes, located in the middle ear. I

Which canal is horizontal and which is vertical: the Haversian canal or Volkmann’s canal?
• Answer: The Haversian canal is vertical, running along the length of the bone, while Volkmann’s canals are horizontal, connecting the Haversian systems.
3. What are the articulations of the clavicle?
• Medial articulation: Sternum
• Lateral articulation: Acromion of the scapula
Explanation: The clavicle articulates medially with the sternum at the sternoclavicular joint and laterally with the acromion of the scapula at the acromioclavicular joint.
4. Which bone doesn’t have a joint?
• Answer: The hyoid bone does not articulate with any other bones; it is unique in that it is suspended by muscles and ligaments in the neck.

Which joint allows for rotational movement?
• a) Hinge joint
• b) Ball-and-socket joint
• c) Pivot joint
• d) Plane joint
Answer: c) Pivot joint
Explanation: Pivot joints, like the atlantoaxial joint between the first and second cervical vertebrae, allow for rotation.

What type of movement does a saddle joint allow?
• a) Flexion and extension only
• b) Rotation only
• c) Flexion, extension, abduction, and adduction
• d) No movement
Answer: c) Flexion, extension, abduction, and adduction
Explanation: Saddle joints, like the thumb’s carpometacarpal joint, allow for a wide range of movements.
3. Which joint is formed between the first metacarpal and the trapezium bone?
• a) Hinge joint
• b) Saddle joint
• c) Pivot joint
• d) Ball-and-socket joint
Answer: b) Saddle joint
Explanation: This joint allows for the thumb’s unique range of motion, including opposition.

Which joint connects the humerus to the scapula?
• a) Elbow joint
• b) Shoulder joint
• c) Wrist joint
• d) Hip joint
Answer: b) Shoulder joint
Explanation: The shoulder joint (glenohumeral joint) is formed by the articulation of the head of the humerus with the glenoid fossa of the scapula.
2. The joint between the tibia and fibula is classified as which type of joint?
• a) Hinge joint
• b) Syndesmosis (fibrous joint)
• c) Ball-and-socket joint
• d) Pivot joint
Answer: b) Syndesmosis (fibrous joint)
Explanation: The joint between the tibia and fibula is a syndesmosis, where the bones are connected by a ligament.

Here’s a summary of lamellae, trabeculae, lacunae, and other related components of bone structure:

• Definition: Lamellae are thin, concentric layers of bone matrix found in both compact and spongy bone.
• Function: In compact bone, they form the structural units known as osteons (or Haversian systems), providing strength and resistance to bending. In spongy bone, lamellae are arranged in a lattice-like pattern that supports bone without adding excessive weight.

• Definition: Trabeculae are the small, rod-like or plate-like structures that make up the internal framework of spongy bone.
• Function: They create a network that supports bone tissue and helps distribute stress across the bone. The spaces between trabeculae are filled with bone marrow, which can be red (producing blood cells) or yellow (fat storage).

• Definition: Lacunae are small cavities within the bone matrix that house osteocytes (mature bone cells).
• Function: They allow for the exchange of nutrients and waste products between osteocytes and the blood supply. Lacunae are connected by tiny channels called canaliculi, facilitating communication and nutrient transfer.

• Osteons (Haversian Systems): The fundamental structural units of compact bone, consisting of concentric lamellae surrounding a central canal (Haversian canal) that contains blood vessels and nerves.
• Canaliculi: Microscopic canals that connect lacunae to each other and to the Haversian canal, allowing for communication and nutrient transfer between osteocytes.
• Endosteum: A thin membrane lining the inner surface of the bone, including the marrow cavity and the surfaces of trabeculae in spongy bone. It plays a role in bone growth and repair.
• Periosteum: A dense layer of connective tissue that covers the outer surface of bones, providing an attachment point for tendons and ligaments, as well as housing blood vessels and nerves.

These components work together to provide the bone with strength, resilience, and the ability to adapt to stress and strain.

Answer 47

Here’s a breakdown of the differences between the olecranon fossa, trochlear fossa, and other related anatomical structures:

• Location: Found on the posterior aspect of the humerus.
• Description: A large, deep depression.
• Function: It accommodates the olecranon process of the ulna during elbow extension. When the elbow is straightened, the olecranon fits into this fossa, allowing for smooth movement.

• Location: Located at the distal end of the humerus, on the anterior aspect.
• Description: A smooth, grooved surface that resembles a pulley.
• Function: It articulates with the trochlear notch of the ulna, allowing for hinge-like motion in the elbow joint. It facilitates flexion and extension of the forearm.

• Location: Also on the anterior aspect of the humerus, just above the trochlear fossa.
• Description: A shallow depression.
• Function: It receives the coronoid process of the ulna during elbow flexion. This allows the forearm to bend smoothly without obstruction.

• Location: Found above the capitulum of the humerus on the anterior side.
• Description: A shallow depression.
• Function: It accommodates the head of the radius during elbow flexion, ensuring proper movement without impinging on surrounding structures.

• Location: At the lateral aspect of the distal end of the humerus.
• Description: A rounded knob.
• Function: It articulates with the head of the radius, allowing for the rotation of the forearm.

• Function: The olecranon fossa allows for elbow extension, while the trochlear fossa allows for flexion and extension. The coronoid and radial fossae facilitate specific movements during elbow flexion.
• Location: The olecranon fossa is posterior, the trochlear fossa is anterior, and the coronoid fossa is positioned above the trochlear fossa.
• Shape: The olecranon fossa is a deep depression, the trochlear fossa is a smooth groove, and the coronoid fossa is a shallow depression.

These features collectively contribute to the function and range of motion of the elbow joint. If you need more detailed information or clarification on any of these structures, feel free to ask!

Question 48

Condyle

•	Description: A rounded, knob-like projection at the end of a bone that articulates with another bone.
•	Function: It forms a joint, allowing for movement and stability. Examples include the medial and lateral condyles of the femur.

3. Epicondyle• Description: A projection situated above a condyle, often serving as an attachment point for ligaments and tendons.
   • Function: It provides leverage for muscles and stability for joints. Examples include the medial and lateral epicondyles of the humerus.
4. Fossa• Description: A shallow depression or hollow in a bone.
   • Function: It may accommodate an organ, muscle, or another bone structure, facilitating movement and support.

Trochanter

•	Description: A large, blunt projection found only on the femur.
•	Function: It serves as an attachment point for muscles, particularly those involved in hip movement (e.g., greater and lesser trochanters).

Foramen

•	Description: An opening or hole in a bone.
•	Function: It allows the passage of blood vessels, nerves, and other structures. Examples include the foramen magnum in the skull and the obturator foramen in the pelvis.

Suture
• Description: An immovable joint between bones of the skull.

Crest
• Description: A prominent ridge of bone.

Process
• Description: A bony prominence or projection.

Sinus• Description: A cavity or hollow space within a bone, often filled with air.

Answer 48

Diaphysis
• The shaft or long part of a long bone, primarily composed of compact bone.
4. Metaphysis
• The region between the diaphysis and epiphysis; where growth occurs in length during development.
5. Articular Cartilage
• A smooth, white tissue that covers the ends of bones at a joint, reducing friction and absorbing shock.
6. Periosteum
• A dense layer of vascular connective tissue that envelops the bones, providing a surface for tendon and ligament attachment and containing bone-forming cell

Spongy Bone (Cancellous Bone)
• A type of bone tissue that has a porous structure and is found at the ends of long bones and in the interior of other bones.

Marrow
• The soft tissue found within the medullary cavity, responsible for producing blood cells (red marrow) and fat storage (yellow marrow).
11. Ligament
• A fibrous connective tissue that connects bones to other bones, providing stability to joints.
12. Tendon
• A fibrous connective tissue that connects muscles to bones, allowing for movement.
13. Joint (Articulation)
• The location where two or more bones meet, allowing for movement and flexibility.

Facet
• A smooth, flat surface on a bone that forms a joint with another bone.
16. Head
• The rounded end of a bone that typically fits into a socket (e.g., the head of the femur).
17. Neck
• The narrowed region of a bone, often found just below the head (e.g., the neck of the femur).
18. Tuberosity
• A large, rounded projection on a bone, serving as an attachment site for muscles or ligaments.
19. Fissure
• A narrow, slit-like opening in a bone, often allowing the passage of nerves and blood vessels.
20. Groove (Sulcus)
• A shallow, linear depression on a bone, often for the passage of blood vessels or nerves.

Question 49

What is trabeculae bone
Radius and ulna which is medial and which is lateral
Same for tibia and fibula
Pivot joint allows for rotational movement
The type of joint in the ankle is hinge
Sphenoid bone forms the back of the head and foramen ovale is located there

Atlas connects skull to vertebral column

Intervertebral joint is a cartilaginous joint

FSH stimulates spermatogenesis

Answer 49

Common Examples of Condyloid (Ellipsoid) Joints

•	Wrist Joint (Radiocarpal Joint): This is one of the best-known examples of a condyloid joint, where the radius articulates with the carpal bones (scaphoid, lunate, and triquetral).
•	Metacarpophalangeal Joints (Knuckles): These joints in the fingers (except the thumb) are condyloid joints that allow flexion, extension, abduction, and adduction.
•	Atlanto-occipital Joint (Neck Joint): This is the joint between the occipital condyles of the skull and the atlas (C1 vertebra). It allows the “yes” movement of the head.
•	Metatarsophalangeal Joints (Toes): Similar to the knuckles in the hand, these are the joints at the base of the toes.