Biology Hidden Gems Eukaryotes and Human Systems Flashcards
Eukaryotes
Have a nucleus and membrane bound organelles
Nucleus
Wrapped in a double phospholipid bilayer called the nuclear envelope or membrane
Nuclear Pores
Nuclear envelope is perforated with large holes that allows RNA to exit but not DNA
Nucleolus
Area where rRNA is transcribed and subunits of the ribosome are assembled; not separated by a membrane
Endocytosis
Three types. Phagocytosis Pinocytosis Receptor mediated endocytosis
Phagocytosis
The cell membrane protrudes outward to envelope and engulf matter -Only a few cells are capable of this and the impetus is the binding of proteins on the particulate matter to protein receptors on the phagocytotic cell -Ex. Antibodies or complement proteins
Pinocytosis
-extracellular fluid is engulfed by small invaginations-Performed in random fashion by most cells; nonselective
Receptor mediated endocytosis
Refers to specific uptake of macromolecules such as hormones, nutrients; ligand binds to a receptor protein on the cell membrane and then moves to a clathrin coated pit that invaginates to form a coated vesicle -Purpose is to absorb the ligands and that’s how it differs from phagocytosis
Phospholipid bilayer of eukaryotic membrane
-Similar to prokaryotic plasma membrane except in eukaryotes the membrane invaginates and separates to form individual, membrane bound compartments and organelles.
Endoplasmic Reticulum
-A thick maze of membranous walls separating the cytosol from the ER lumen (cisternal space) -Contiguous with the cell membrane and nuclear membrane -Contiguous in places with the space between the double bilayer of the nuclear envelope
Rough/ Granular ER
ER near the nucleus has many ribosomes attached to it on the cytosolic side -Translation of the Rough ER propels proteins into the ER lumen as they are created -These proteins are tagged with a signal sequence of amino acids and sometimes glycosylated (carbohydrate chains attached) -Proteins move through the lumen towards the Golgi apparatus
Golgi Apparatus
Series of flattened, membrane bound sacs -Organizes and concentrates the proteins -Proteins without signal sequences are put in secretory vesicles and sent out of the cell -Can modify proteins by removing amino acids or glycosylating them -Some polysaccharide formation takes place in the golgi apparatus -End product is a vesicle filled with proteins that can be released from the Golgi to mature into lysosome transported to other parts of the cell such as the mitochondria or even the ER.
Secretory Vesicles
-Supply the membrane with its proteins and also act in membrane expansion -Endocytotic vesicles from the membrane are transferred to the Golgi for recycling of the cell membrane
Lysosomes
-contain acid hydrolases (hydrolytic enzymes that function best in an acid environment) such as proteases, lipases, nucleases, and glycosidases -These enzymes are capable of breaking down everything -pH 5 interior -Fuse with endocytotic vesicles and digest their contents; anything not digested is ejected from the cell -Sometimes they autolyse to kill the cell
Smooth ER
-Hydrolyzes G6P to glucose ; an important step in making glucose from glycogen -Shares in role of cholesterol formation and subsequent change into steroids with cytosol -Most of the phospholipids in the cell membrane are synthesized in the smooth ER -Oxidizes foreign substances, detoxifying drugs, pesticides, toxins, and pollutants
Adipocytes
-Contain mainly fat droplets -Important in storage and body temp regulation
Peroxisomes
-Vesicles in the cytosol -Growth by incorporating lipids and proteins from the cytosol. -Rather than budding off membranes like lysosomes, peroxisomes self replicate -Involved in production and breakdown of hydrogen peroxide -Inactivate toxic substances such as alcohol, regulate oxygen concentration, play a role in the synthesis and breakdown of lipids and in the metabolism of nitrogenous bases and carbohydrates.
Cell can be divided into
cytosol and ER lumen
Stuff can reach the ER lumen by
endocytosis without ever transporting across a membrane
Rough ER has ribosomes attached to its
cytosol
Cytoskeleton
-Structure and motility of a cell is determined by a network of filaments -Anchors some membrane proteins and other cellular components, moves components within the cell, and moves the cell itself.
Microtubules
-Larger than microfilaments and are involved in flagella and cilia construction, and the spindle apparatus -Rigid hollow tubes made from a protein called tubulin -Makes up the mitotic spindle
Tubulin
Globular protein that polymerizes into long straight filaments under certain conditions
Axoneme
Major portion of the flagellum and cilium contains 9 pairs of microtubules to its neighbor -Have a + and - end, -end attaches to microtubule-organizing center -Microtubules grow away from the MTOC at its +end -Major MTOC is the centrosome; centrioles function in production of flagella and cilia
Microfilaments
-Smaller than microtubules -Actin forms a major component of microfilaments -Produce the contracting force in muscle and are involved in cytoplasmic streaming, phagocytosis, and microvilli movement
Tight Junctions
-Form a watertight seal from cell than can block water, ions and other molecules from moving around or past cells. -Epithelial tissue of organs are held together by tight junctions to prevent waste from flowing
Desmosomes
Join two cells at a single point by attaching directly to the cytoskeleton of each cell
Gap junctions
-Small tunnels connecting cells allowing molecules and ions to move between cells -In cardiac muscle provide for the spread of the action potential
Mitochondria
-Krebs cycle happens here -DNA replicates independently; contains no histones or nucleosomes -Have their own ribosomes -Inner membrane invaginates to form cristae -Holds the electron transport chain -Area between inner and outer membrane is intermembrane space
Tissue
Cells that form groups of similar cells that work together for a common purpose
Extracellular Matrix
Some cells called fibroblasts secrete fibrous proteins such as elastin and collagen to form a molecular network that holds tissue cells in place. -Can provide structural support, help to determine shape and motility, and affect cell growth
Types of tissue
epithelial tissue, muscle tissue, connective tissue, and nervous tissue
Epithelial tissue
Separates free body surface from their surroundings
Connective tissue
Characterized by extensive matrix. Ex: Blood, lymph, bone, cartilage, etc
Neuronal communication
Tends to be rapid, direct and specific
Hormonal communication
Tends to be slower, spreads throughout the body, and affects many cells and tissues in different ways
Neurons
Rely on glucose for energy, don’t need insulin; depend on aerobic respiration efficiency -Rely on blood because they don’t have sufficient glycogen or oxygen
Electrical Synapses
Transmit in both directions unlike chemical synapses and with more speed
White Matter
Myelinated axons
Grey Matter
Neuronal cell bodies
Saltatory Conduction
Jumping nodes of ranvier
CNS
Integrates nervous signal between sensory and motor neurons
PNS
-Somatic and autonomic nervous system
Somatic nervous system
Designed to respond primarily to external environment; sensory and motor functions; uses AcH -Controls motor functions -Sensory input
ANS
-involuntary -Sympathetic and Parasympathetic -Most internal organs innervate by both
Sympathetic Nervous System
Part of ANS Dilates pupils Increases heart beat rate and stroke volume -Constricts blood vessels around digestive and excretory systems to increase blood flow to muscles -postganglionic neurons are adrenergic -“Fight or Flight”
Parasympathetic Nervous system
“Rest and Digest” conserves energy as it slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles in the gastrointestinal tract.
Lower Brain
-Medulla, hypothalamus, cerebellum -Integrates subconscious activities such as respiration, arterial pressure, salivation, emotions, reactions to pain and pleasure
Higher Brain
-Cerebral cortex, stores memories and processes thoughts
Cornea
Nonvascular
Lens
Flattened by zonule fibers; when ciliary muscles contract the zonule fibers relax and the lens becomes spherical to see close up
Cones
Distinguish colors
Rods
Work in low light, only in black and white
Three parts of the ear
Outer ear Middle ear: Malleus, Incus, stapes Inner ear: Wave in inner ear moves through cochlea. Movement is detected by hair cells and organ of Corti. Semicircular canals-detect orientation
Endocrine glands
Release hormones directly into the blood
Exocrine glands
Release enzymes to the external environment through ducts -Ex. Sweat, oil, mucous
Effects of endocrine system tend to be slower and longer lasting than
nervous system
All hormones need a
receptor–either on the membrane or in the cell
Hormone types
peptide hormones, steroid hormones, tyrosine derivatives
Peptide Hormones
Derived from peptides. -May be large or small and often attached to carbohydrates -ALL are synthesized in the rough ER as a preprohormone where it is sent to the Golgi -Are water soluble
Steroid Hormones
-Derived from cholesterol -Formed in the smooth ER and mitochondria since they are lipids -Require a protein transport molecules through the blood but diffuse across the membrane on their own -Hit receptors in the cytosol where they are transported to the nucleus and act at the transcription level -Typical effect is to increase certain membrane or cellular proteins -Important ones are the glucocorticoids and mineral corticoids of the adrenal cortex and gonadal hormones: estrogen, progesterone, and testosterone
Glucocorticoids
are part of the feedback mechanism in the immune system, which reduces certain aspects of immune function, such as inflammation. They are therefore used in medicine to treat diseases caused by an overactive immune system, such as allergies, asthma, autoimmune diseases, and sepsis.
Tyrosine Derivatives
-T3 and T4, and catecholamines (formed in the adrenal medulla) -Epinephrine and norepinephrine are water soluble -Formed by enzymes in the cytosol or on the rough ER -Thyroid hormones are lipid soluble and must be carried in blood by plasma protein carriers -Their high affinity to their binding proteins in the plasma and in the nucleus create a latent period in their response and increase the duration of the effect of the thyroid hormones. -Increase the transcription of large numbers of genes in nearly all cells of the body
Endocrine gland tend to
over secrete their hormones. -The gland lags behind the effector, respond to the condition instead of creating it -Ex. High insulin levels do NOT create low blood glucose, they are a response to blood glucose -Ex. If you have high blood pressure and decreased urine output you have low ADH levels because ADH is responding to the condition
Anterior Pituitary hormones
FLAT PEG: FSH (Follicle Stimulating Hormone), LH (Leutinizing Hormone), ACTH (Adrenocorticotropic Hormone), TSH (Thyroid Stimulating Hormone), Prolactin, Endorphins, and Growth Hormones. This mnemonic is also useful because it can help you remember which hormones belong to which class. There are two important classes of hormones: tropic (hormones that act on other endocrine glands) and direct (hormones that act directly on some other, non-endocrine, part of the body). The FLAT hormones are all tropic hormones (you can remember this by picturing a flat, tropical beach) and the PEG hormones are direct (you can remember this because you can picture a peg going directly into a piece of wood). Releases ONLY peptide hormones
hGH
-Increases growth in almost all cells of the body -Increases episodes of mitosis, cell size, rates of protein synthesis, mobilizing fat stores, use of fatty acids for energy, decreasing use of glucose -Increases AA transport across membrane, translation and transcription, and decreases breakdown of protein and AA
Endorphins
Release a happy feeling in the brain. Work on opiate receptors in the brain and decrease pain
Adrenocorticotropic hormone (ACTH)
-Stimulated by stress -Stimulates the adrenal cortex to release glucocorticoids (stress hormones)
Thyroid stimulating hormone (TSH)
-Stimulates thyroid to release T3 and T4 -Increases thyroid cell size, number -T3 and T4 concentrations have a negative feedback effect on TSH release
FSH
Follicle-stimulating hormone (FSH) is a gonadotropin, a glycoprotein polypeptide hormone. FSH is synthesized and secreted by the gonadotropic cells of the anterior pituitary gland, and regulates the development, growth, pubertal maturation, and reproductive processes of the body.
LH
In women, the hormone stimulates the ovaries to produce oestradiol. Two weeks into a woman’s cycle, a surge in luteinizing hormone causes the ovaries to release an egg during ovulation. If fertilization occurs, luteinizing hormone will stimulate the corpus luteum, which produces progesterone to sustain the pregnancy
Prolactin
-Promotes lactation -Although hypothalamus has a stimulatory effect on the release of all other anterior pituitary hormones it has an inhibitory effect on the release of prolactin -Release stimulated by suckling
Posterior Pituitary
-Oxytocin and ADH (vasopressin) are synthesized in the neural cell bodies of the hypothalamus
Oxytocin
a peptide hormone that increase uterine contractions and causes milk to be ejected from the breasts
ADH (vasopressin)
-peptide hormone that causes the collecting ducts of the kidney to become permeable to water, reducing the amount of urine and concentrating it -Since fluid is reabsorbed it also increase blood pressure
Adrenal Glands
Cortex, mineral corticoids, glucocorticoids
Cortex
Secretes ONLY steroids; mineral corticoids and glucocorticoids
Mineral Corticoids
Affect electrolyte balance in the bloodstream
Glucocorticoids
Increase blood glucose concentration and have an even greater effect on fat and protein metabolism
Adrenal Cortex
Aldosterone, Cortisol, Catecholamines the outer part of the gland—produces hormones that are vital to life, such as cortisol (which helps regulate metabolism and helps your body respond to stress) and aldosterone (which helps control blood pressure)
Aldosterone
A steroid is a mineral corticoid that acts in the distal tube and collecting duct to increase Na+ and Cl- reabsorption and K+ and H+ secretion. Causes an increase in blood pressure.
Cortisol
a steroid glucocorticoid that increase blood glucose levels by stimulating gluconeogenesis (creation of glucose and glycogen from amino acids, glycerol, lactic acid) in the liver -degrades adipose tissue to fatty acids to be used for cellular energy -Stress hormone -Diminishes capacity of immune system to fight infection -Degradation of nonhepatic proteins and amino acids and an increase in hepatic (liver) amino acids and proteins
Catecholamines
-Tyrosine and derivatives synthesized in the adrenal medulla -Epinephrine and norepinephrine-vasoconstrictors of most internal organs and skins but are vasodilators of skeletal muscles
Thyroid Hormones
T3 and T4-lipid soluble tyrosine derivatives that diffuse through the lipid bilayer and act in the nucleus of the cells of their effector -Increase resting metabolic rate -Secretion is regulated by TSH
Calcitonin
-Large peptide hormone that slightly decreases blood calcium level by decreasing osteoclast activity and number
Pancreas
Insulin-a peptide hormone released when blood levels of carbohydrates or proteins are high. -Carbohydrates are stored as glycogen in the liver and muscles, fat is stored in adipose tissue, and amino acids are taken up and turned into proteins. -Permeability of membrane to AA is increased -Intracellular metabolic enzymes are activated and even translation and transcription rates are affected -Effect is to lower blood glucose levels
Glucagon
-a peptide hormone that stimulates glycogenolysis and gluconeogenesis in the liver -Breaks down adipose tissue increasing the fatty acid level in the blood. -Net effect is to raise blood glucose
Parathyroid Hormone
-A peptide that increases blood calcium -Increases osteocyte absorption of calcium and phosphate from the bone and stimulates proliferation of osteoclasts. -Increases renal calcium reabsorption and renal phosphate excretion -regulated by calcium ion plasma concentration
Reproduction of sperm happens in the
seminiferous tubules
Spermatogonia located in the seminiferous tubules arise from epithelial tissue to become
spermatocytes, spermatids, and then spermatozoa
Sertoli cells stimulated by FSH surround and nurture the
spermatocyte and spermatids
Leydig cells release
testosterone when stimulated by LH
Sertoli cells secrete
inhibin, a peptide hormone that acts on the pituitary gland to inhibit FSH secretion
Testosterone is the primary
androgen (male sex hormone) and stimulates germ cells to become sperm
Testosterone is responsible for
secondary sex characteristics such as englargement of the larynx, growth of seminal vesicles. -Stimulates growth spurt at puberty and closure of the epiphyses of the long bones, ending growth
Spermatid
-As it becomes a spermatozoan it loses its cytoplasm and forms the head, midpiece, and tail -Head of sperm has nuclear material and acrosome that contains lysosome-like enzymes to penetrate the egg
once freed in the tubule lumen the spermatozoon is carried to the
epididymus. On ejaculation is travels through the vas deferens into the urethra.
Semen is the mixture of
spermatozoa and fluid from the seminal vesicles, prostate, and the bulbourethral (Cowper’s) glands
Spermatozoa becomes active for fertilization in a process called
capacitation in the vagina
Oogenesis begins in the
ovaries of the fetus
All the eggs are
arrested as primary oocytes at birth
At puberty, FSH stimulates growth of
granulosa cells around the primary oocyte. Granulosa cells secrete a viscous substance around the egg called the zona pellucida. This structure is called the primary follicle. -Next. theca cells differentiate from the interstitial tissues and grow around the follicle to form a secondary follicle. -Upon stimulation by LH, theca cells secrete androgen, which is converted to estradiol (a type of estrogen) by the granulosa cells in the presence of FSH and secreted into the blood -The follicle grows and bulges from the ovary -Typically, estradiol inhibits LH secretion by the anterior pituitary -Luteal Surge- However, just before ovulation (bursting of the follicle) the estradiol levels rise rapidly causing a dramatic increase in LH -Results from a positive feedback loop of rising estrogen levels which increase LH levels, which increase estrogen. -Causes the follicle to burst, releasing the egg (now a secondary oocyte)into the body cavity. -Egg is swept into fallopian tube or oviduct -remaining portion of follicle becomes the corpus luteum
Corpus Luteum
secretes estradiol and progesterone throughout pregnancy, or in the case of no pregnancy, for about two weeks until it turns into the corpus albicans
Female Menstrual Cycle phases
- Follicular phase- begins with the development of follicle and ends at ovulation 2. Luteal phase-begins with ovulation and ends with the degeneration of the corpus luteum 3. Flow-shedding of uterine lining lasting about 5 days
Fertilization
-Once in the fallopian tube, the egg is swept towards the uterus by cilia -Fertilization takes place in the fallopian tube -Entry of the sperm activates the cortical reaction which prevents other sperm from fertilizing the same egg -Now the oocyte goes through the second meiotic division to become an ovum and release a second polar body -Occurs when the nuclei of the ovum and sperm fuse to form the zygote
Cleavage
-begins while the zygote is still in the fallopian tube -Zygote goes through many cycles of mitosis–when it is 8 cells its called a morula
Morula
8 cells
Blastocyst
Fluid filled ball that forms the morula continues to divide
Implantation
When the blastocyst lodges in the uterus on the 5th to 7th day of ovulation
Human Chorionic Gonadotropin (HCG)
-A peptide hormone that is released by the egg upon implantation that prevents degradation of corpus luteum and maintains its secretion of estrogen and progesterone
Placenta
-Formed from the tissue of the egg and the mother and takes over the job of hormone secretion -At 3 months begins secreting its own estrogen and progesterone while lowering the secretion of HCG
Determination
-Process where a cell becomes committed to a specialized developmental path (a certain tissue)
Differentiation
-The specialization that occurs at the end of development forming a specialized tissue cell
Gastrula
-Formation begins in the second week and is called gastrulation -Cells begin to slowly move about the embryo for the first time -Three primary layers are formed: ectoderm, endoderm (lining of digestive tracts, liver, and pancreas), mesoderm (stuff that lies between the inner and outer covering of the body—muscle, bone, etc) -In the third week the gastrula develops into the neurula in a process called neurulation -Notochord-induces ectoderm to form neural plate
Ectoderm
the outermost layer of cells or tissue of an embryo in early development, or the parts derived from this, which include the epidermis and nerve tissue.
Endoderm
lining of digestive tracts, liver, and pancreas), give rise to certain organs, among them the colon, the stomach, the intestines, the lungs, the liver, and the pancreas
Mesoderm
stuff that lies between the inner and outer covering of the body—muscle, bone, etc gives rise to the skeletal muscles, smooth muscle, blood vessels, bone, cartilage, joints, connective tissue, endocrine glands, kidney cortex, heart muscle, urogenital organ, uterus, fallopian tube, testicles and blood cells from the spinal cord and lymphatic tissue
What is apoptosis regulated by
proteins
Digestive Tract
Mouth, esophagus, stomach, small intestine (duodenum, ileum, jejunum); large intestine (ascending, transverse, descending, sigmoid colon); rectum, anus
Digestion begins with
alpha amylase in the saliva. -Alpha amylase begins breaking down the long straight chains of starch into polysaccharides -Starch is the major carbohydrate in the human diet
Peristaltic action
Moves the bolus down the esophagus by swallowing; smooth muscle -wave motion -saliva lubricates food to help it move down the esophagus
Stomach
Begins protein digestion with the enzyme pepsin -Low pH of 2 in stomach assists protein digestion by denaturing proteins; kills bacteria
Chyme
Stomach mixes and stores food reducing it to a semi-fluid mass
Exocrine glands
The secretions of the exocrine gastric glands - composed of the mucous, parietal, and chief cells - make up the gastric juice
Four major cell types of the stomach
Mucous cells, Chief (peptic cells), Parietal (oxyntic cells), G cells)
Mucous cells
line stomach walls to protect cells from acidic environment; mucous is mainly sticky glycoproteins; some secrete small amount of pepsinogen
Chief (peptic) cells
secrete pepsinogen deep in the exocrine gland; pepsinogen activated by low pH (broken down into pepsin by gastric acid)
Parietal (oxyntic cells)
secrete HCl; lowers pH of stomach and raises pH of blood -bicarbonate released outside cell, hydrogen from carbonic acid released into cell
G cells
secrete gastrin, a large peptide hormone, into the blood and stimulates parietal cells to secrete HCl
Major hormones that affect secretion of stomach juices are
AcH, gastin, and histamine. AcH increases secretion of all cell types.
Small Intestine
90% of digestion and absorption occurs here -Digestion happens in duodenum; absorption in jejunum and ileum
Small intestinal wall
Nutrients absorbed through the wall of the small intestine pass into the capillary network and the lacteal
Villi
-finger-like projections in outer layer -Increase surface area of the wall allowing for greater digestion and absorption -within each villus is a capillary network and a lymph vessel called a lacteal
Microvilli
-smaller finger-like projections on each villus -appear as fuzzy covering called the brush border
Brush Border
-in small intestine -Contains membrane bound digestive enzymes that are carbohydrate digesting -Contains protein digesting enzymes called peptidases -Contains nucleotide-digesting enzymes called nucleosidases -Enterocytes-cells of the brush border that reduce di-tri-peptides to AA
Goblet Cells
-Epithelial cells that secrete mucus to lubricate the intestine and protect the bush border from mechanical and chemical damage
Lysozyme
Regulates bacteria within the intestine
Pancreas
Connected to Duodenum: Trypsin, chymotrypsin, pancreatic amylase, lipase, ribonuclease, deoxyribonuclease.
Duodenum
First section of small intestine. Connected to pancreas. Has a pH of 6 due to bicarbonate ion secreted by the pancreas
Trypsin and Chymotrypsin
Degrades proteins into small polypeptides; most proteins reach the brush border as small polypeptides where they are reduced to AAs before they are absorbed by enterocytes
Pancreatic Amylase
hydrolyzes polysaccharides to disaccharides, degrades nearly all carbohydrates from the chyme into small glucose polymers
Lipase
degrades fat (triglycerides)
Bile
-produced in the liver and stored in the gall bladder -weakens bonds between fat (emulsifies) to increase surface area so lipase can break it down -reabsorbed by small intestine and sent back to the liver
Hormones in the small intestine cause
increased blood insulin levels after the meal
Large Intestine
-Major functions are water absorption and electrolyte absorption -When this fails diarrhea results -Contains E.Coli -Produces Vitamin K, B12, thiamin and riboflavin
Carbohydrates
-Sodium is pumped out of the enterocyte -Glucose is dragged into the enterocyte by sodium (secondary active transport) -One of the jobs of the liver is to maintain a fairly constant blood glucose level -In all cells except enterocytes and the cells of the renal tubule glucose is transported from high concentration to low concentration
Glycogenesis
Formation of glycogen
Glycogenolysis
Break down of glycogen. takes place in the liver when the blood glucose level decreases
Protein digestion results in
amino acids, dipeptides and tripeptides. Absorption of many of these products occur via a cotransport mechanism down the concentration gradient of sodium
All dietary protein it broken down into
its amino acids before being absorbed into the blood
All polypeptides absorbed into an enterocyte are hydrolyzed to their
AA components by enzymes within the enterocytes. Then they are absorbed quickly into the blood and taken up by all cells of the body; especially the liver
Transport of proteins may be facilitated or active–
never passive because of polarity and size
Cell immediately creates proteins from
AAs to keep concentration low
When AAs reach their upper limit for protein storage AAs can be
burned for energy or converted to fat for storage
Proteins are easily
broken down and returned to blood when needed
Ammonia
Protein that is a nitrogen containing compound produced as a by-product of gluconeogenesis. Nearly all ammonia is converted into Urea
Most dietary fats consist of
triglycerides which are broken down to monoglycerides and fatty acids before they are shuttled to the brush border by bile micelles and diffuse to the enterocyte membrane
Once inside the enterocyte membrane, monoglycerides/fatty acids are
turned back into triglycerides at the smooth ER
Newly synthesized triglycerides aggregate within the
smooth ER lumen. Moved to Golgi apparatus and are released via exocytosis (chylomicrons)
Major absorption of fat occurs in the
liver and adipose tissue
The first stop for most of the digested fat is the
liver
Albumin
Most fatty acids are transported in the blood with albumin
Lipoproteins
-Made from triglycerides, cholesterol, phospholipids, and proteins -Most are made in the liver -VLDL transport triglycerides from the liver to adipose tissue -Intermediate and LDL transport cholesterol and phospholipids to the cells of the body
Vena Cava
a large vein carrying deoxygenated blood into the heart. There are two in humans, the inferior vena cava (carrying blood from the lower body) and the superior vena cava (carrying blood from the head, arms, and upper body). All blood received by the liver moves to the hepatic vein and leads to the vena cava
Blood storage of liver
Liver can expand to store blood for the body
Blood filtration (liver)
Kupfer cells phagocytize bacteria picked up from the intestines
Carbohydrate metabolism of the liver
Liver maintains normal blood glucose levels through gluconeogenesis, glycogenesis, and storage of glycogen
Fat metabolism of the liver
Liver synthesizes bile from cholesterol and converts carbohydrates and proteins into fat; oxidizes fatty acids for energy and forms most lipoproteins
Protein metabolism of the liver
Liver deaminates amino acids; forms urea from ammonia in the blood; synthesizes fibrinogen, prothrombin, albumin, nonessential amino acids
Fibrinogen
Fibrinogen is a protein, specifically a clotting factor (factor I), that is essential for proper blood clot formation
Prothrombin
. Prothrombin is transformed into thrombin by a clotting factor known as factor X or prothrombinase; thrombin then acts to transform fibrinogen, also present in plasma, into fibrin, which, in combination with platelets from the blood, forms a clot
Albumin
Albumin is a protein made by your liver. Albumin helps keep fluid in your bloodstream so it doesn’t leak into other tissues. It is also carries various substances throughout your body, including hormones, vitamins, and enzymes. Low albumin levels can indicate a problem with your liver or kidneys.
Detoxification (liver)
detoxified chemicals are excreted by the liver as part of bile or polarized so they may be excreted by the kidney
Erythrocyte destruction of the liver
Destroy irregular erythrocytes
Vitamin storage of the liver
Liver stores vitamins A, D, and B12
Ketosis/ Acidosis
When the liver mobilizes fat or protein for energy blood acidity increases
Kidney
You have two kidneys. They are made up of an outer cortex and an inner medulla
Kidney functions
- Excretes waste products such as urea, uric acid, ammonia, and phosphate 2. Maintains homeostasis of body fluid volume and solute composition 3. Controls plasma pH
Urine is created by the kidney and emptied into the
renal pelvis
Renal pelvis is emptied into the
ureter, which carries urine to the bladder, which is then drained by the urethra
Nephron
Functional unit of the kidney
Blood of the kidney flows into the first capillary bed called the
glomerulus
Renal Corpuscle
made up by bowman’s capsule and the glomerulus.
Fenestrations
hydrostatic pressure forces plasma through fenestrations of the glomerular endothelium and into bowman’s capsule -act as sieve filtering blood cells and large proteins entering bowman’s capsule
Proximal Tubule
-where most reabsorption occurs; filtrate from bowman’s capsule flows here. -Reabsorption of nearly all glucose, most proteins, and other solutes -Water is reabsorbed here -Drugs, toxins, and other solutes are secreted into the filtrate by the cells here -Hydrogen ions are secreted through an antiport system with sodium -Net result is to reduce the amount of filtrate in the nephron while changing the solute composition without changing the osmolarity
Loop of Henle
-Dips into the medulla -Function is to increase the solute concentration and thus the osmotic pressure -As filtrate descends into the medulla water passively diffuses out of the loop and into the medulla; this area of the medulla has low permeability to salt so filtrate osmolarity goes up -As filtrate rises out salt diffuses out (passively then actively) -Ascending loop is permeable to salt but impermeable to water
Distal Tubule
-Reabsorbs Na+ and Ca2+ while secreting K+, H+ and HCO3- -Aldosterone increases sodium and potassium membrane proteins -Net effect is to lower the filtrate osmolarity -ADH increases the permeability of the cells to water so in the presence of ADH water flows from the tubule concentrating the filtrate
Collecting Tube
-At the end of the distal tube -Carries the filtrate to the highly osmotic medulla -Impermeable to water but sensitive to ADH -When ADH is around water exits into the medulla concentrating the urine
Juxtaglomerular Apparatus
-Monitors filtrate pressure in the distal tube -Specialized cells secrete renin which ultimately stimulates the adrenal cortex to secrete aldosterone
Filtration occurs in the renal corpuscle, reabsorption mostly in the
proximal tubule
The loop of Henle concentrates solute in the
medulla
Distal tubule empties into the
collecting duct; collecting duct concentrates the urine
Amount of filtrate is related to the
hydrostatic pressure of the glomerulus
Ascending loop of henle actively transports
sodium into the kidney
Systemic Circulation
-Beginning with the left ventricle, blood is pumped through the aorta. -From the aorta branch many smaller arteries which branch into small arterioles and then capillaries -Blood from the capillaries is collected into venules which then collect into larger veins -These larger veins collect again into the superior inferior vena cava -Vena cava empties into the right atrium of the heart
Pulmonary Circulation
-From the right atrium blood is squeezed into the right ventricle -The right ventricle pumps blood through the pulmonary arteries, to the arterioles and then to the capillaries of the lungs. -From the capillaries of the lungs blood collects in venules, then veins, and finally in the pulmonary veins leading to the heart. -Pulmonary veins empty into the left atrium which fills the left ventricle
Systole
Occurs when ventricles contract
Distole
Occurs during relaxation of the entire heart and then contraction of the atria
The rate of distole and systole contractions is controlled by the
autonomic nervous system but the autonomic nervous system doesn’t initiate these contractions
Sinoatrial Node (SA node)
-The heart contracts automatically paced by a specialized group of muscle cells called the sinoatrial nose (SA node) in the right atrium -Contracts by itself rhythmically spreading its contractions to the surrounding cardiac muscles via electrical synapses made from gap junctions -Pace of the SA node is faster than heartbeats but its innervated by the vagus nerve slowing contractions -Spreads around both atria causing them to contract and at the same time spreads to the atrioventricular node (AV node)
Atrioventricular Node (AV node)
-Slower to contract, creating a delay which allows the atria to finish their contraction and to squeeze their contents into the ventricles before the ventricles begin to contract -From the AV node the AP moves down conductive fibers called the bundle of His
Bundle of His
-located in the walls separating the ventricles -The AP branches out through the ventricular walls via conductive fibers called Purkinje fibers where the AP is then spread through gap junctions from one cardiac muscle to the next.
Purkinje fibers
Fibers in the ventricles allow for a more unified and stronger contraction
Arteries
-Elastic and stretch as they fill with blood -Wrapped in smooth muscle that is typically innervated by the sympathetic nervous system -Epinephrine is a vasoconstrictor that causes arteries to narrow -larger arteries have less smooth muscle and are thus less affected by sympathetic innervation
Arterioles
-Very small, wrapped by smooth muscle -Constriction and dilation can be used to regulate blood pressure and reroute blood
Capillaries
-Microscopic blood vessels -Nutrient and gas exchange takes place here -Four methods of crossing capillary walls 1. Pinocytosis 2. Diffusion or transport through capillary cell membranes 3. Movement through pores called fenestrations 4. Movement through the space between the cells -As blood flows in hydrostatic pressure is greater than osmotic pressure and net flow is out of the capillary and into the interstitium -Although osmotic pressure is constant through the capillary towards the end hydrostatic pressure drops so net fluid flow is into the capillary
Hydrostatic versus osmotic pressure
Whereas hydrostatic pressure forces fluid out of the capillary, osmotic pressure draws fluid back in. Osmotic pressure is determined by osmotic concentration gradients, that is, the difference in the solute-to-water concentrations in the blood and tissue fluid
Venules and Veins
-Similar to arterioles and arteries -Lumen is larger than the lumen of comparable arteries and veins contain a far greater volume of blood -Veins, venules, and venus sinuses in the systemic circulation hold about 64 % of the blood in a body at rest and act as a reservoir. -Arteries, arterioles, and capillaries in the systemic circulation carry about 20%
Blood volume flow rate is
approximately constant
Veins have a valve system that prevents back flow to compensate for
the lower pressure in the veins
An artery carries blood
away from the heart
A vein carries blood
towards the heart
Don’t confuse oxygenated blood with the definition of arteries; the pulmonary arteries contain
the most deoxygenated blood in the body
Respiratory system flow
Air enters through the nose, moves through the pharynx, larynx, trachea, bronchi, bronchioles, and into the alveoli where oxygen is exchanged for CO2 with blood.
Diaphragm
-When this contract air is inhaled -Is a skeletal muscle innervated by the phrenic nerve
Nasal cavity
Space inside the nose that filters, moistens, and warms incoming air
Coarse Hair inside the nose
At the front of the cavity traps large dust particles
Mucus
Secreted by goblet cells traps smaller dust particles and moistens the air
Cilia
Moves the mucus and dust back toward the pharynx so that it may be removed by spitting or swallowing
Pharynx
functions as a passageway for food and air
Larynx
Contains vocal cords, sits behind the epiglottis -When nongaseous material enters, coughing occurs to force the material out
Epiglottis
Cartilaginous member that prevents food from entering the trachea when swallowing
Trachea (windpipe)
lies in front of the esophagus -Mucus and cilia collect dust in the trachea and move it towards the pharynx
Bronchi
-There is a right and left bronchi that air from the trachea spits into before it enters the lungs
Bronchioles
Each bronchus branches many more times and ends in tiny bronchioles
Alveoli
bronchioles terminate in grape like clusters called alveolar sac composed of tiny alveoli -From each alveolus oxygen diffuses into a capillary where it is picked up by red blood cells -The red blood cells release CO2 which diffuses into the alveolus and is expelled upon exhalation
Oxygen diffuses into the capillaries and carbon dioxide diffuses into the
alveoli
98% of the oxygen in the blood binds rapidly and reversibly with the protein
hemoglobin inside the erythrocytes forming oxyhemoglobin
Hemoglobin
-Heme cofactor is an organic molecule with an atom of iron at its center -Each of the 4 iron atoms in hemoglobin bind one O2 molecule increasing the likelihood of a second molecule binding
As O2 pressure increases, the O2 saturation of hemoglobin
increases sigmoidally
Oxygen dissociation curve
-Is shifted to the right by an increase in carbon dioxide pressure, hydrogen ion concentration, or temperature -A shift to the right indicates a lowering of hemoglobin’s affinity for oxygen -Carbon monoxide has more than 200 times greater affinity for hemoglobin than does oxygen but shifts the curve to the left
Carbon dioxide
Carried by the blood in three forms; physical solution, bicarbonate ion, in carboamino compounds (compounds with hemoglobin,etc)
Carbonic anhydrase
-An enzyme that catalyzes this reversible reaction -CO2+H2O—->HCO3- +H+ -Because carbonic anhydrase is inside the red blood cell and not in the plasma, when carbon dioxide is absorbed in the lungs, bicarbonate ion diffuses into the cell. To balance the electrostatic forces, chlorine moves out of the cell in a phenomenon called the chloride shift
Haldane Effect
-When hemoglobin becomes saturated with oxygen, its capacity to hold CO2 is reduced. Facilitates the transfer of carbon dioxide from blood to lungs, and from tissues to blood. -Reduced hemoglobin (Hb, hemoglobin without oxygen) acts as a blood buffer by accepting protons -It is the greater capacity of reduced hemoglobin to form carbamino hemoglobin that explains the Haldane effect.
In the case of acidosis (too much acid in the blood), the body compensates by
increasing the breathing rate thereby expelling carbon dioxide and raising the pH of the blood
Central and peripheral chemoreceptors monitor CO2 concentration in the blood and
increase breathing when levels get too high
Lymphatic system
collects interstitial fluid and returns it to the blood. Proteins and large particles that can’t be taken up by the capillaries are removed by the lymph system.
The lymphatic system reroutes low soluble fat digestates around the small capillaries of the intestine and into the
large veins of the neck
Most tissues are drained by
lymphatic channels
lymph system is an
open system
Lymph capillaries are like
tiny fingers protruding into the tissues
To enter the lymph system, interstitial fluid flows between
overlapping endothelium cells
interstitial fluid is slightly
fluid
As the interstitial pressure rises toward zero, lymph flow
increases
Factors that affect interstitial pressure include:
blood pressure, plasma osmotic pressure, interstitial pressure (from proteins, infectious response, etc), permeability of capillaries
Lymph vessels are constructed with
intermittent valves, which allow fluid to flow only in one direction
Smooth muscle in the walls of larger lymph vessels contract when
stretched
Lymph from the right arm and head enters the blood through
the lymphatic duct. The rest of the body is drained by the thoracic duct
Throughout the lymphatic system are many lymph nodes, containing large quantities of
lymphocytes
Blood is what type of tissue?
connective. Like any connective tissue is contains cells and a matrix
Blood regulates
the extracellular environment of the body by transporting nutrients, waste products, hormones and even heat
Plasma contains the
matrix of the blood, which includes water, ions, urea, ammonia, proteins, and other organic and inorganic compounds
Albumin and immunoglobins are
clotting factors Albumin-transports fatty acids and steroids and regulates the osmotic pressure of blood
Plasma in which the clotting protein fibrinogen is removed is called
serum
An important function of plasma proteins is to
act as a source of amino acids for tissue protein replacement
All blood cells differentiate from stem cells in the
Bone marrow
Erythrocytes
Red blood cells -No organelles, not even a nucleus-so not mitosis -like bags of hemoglobin and have no nucleus or organelles -Know the main function is to transport O2 and CO2
Leukocyte
white blood cells -No nucleus-don’t undergo mitosis -Don’t have hemoglobin -Protect body from foreign invaders -Granulocytes-live a short time (multiply quickly to fight an infection); function nonspecifically towards all infectious agents -Agranulocytes-work against specific agents of infection
Platelets
-Small portions of membrane-bound cytoplasm torn from megakaryocytes -tiny cells without a nucleus -Contain actin and myosin, residuals of the Golgi and the ER, mitochondria -Its membrane is designed to avoid adherence to healthy endothelium while adhering to injured endothelium -When platelets come across injured endothelium they become sticky and adhere releasing various chemicals and activating other platelets
Coagulation
A process involving many factors that starts with platelets includes the plasma proteins prothrombin and fibrin
Inflammation
-Dilation of blood vessels, increased permeability of capillaries, swelling of tissue cells and migration of granulocytes and macrophages in response to injury to tissue cells -Part of the effect is to wall off the effected tissue and local lymph vessels from the rest of the body to impede the spread of the infection
Macrophages
-Infectious agents that are able to pass through the skin or the digestive defenses and enter the body are first attacked by macrophages -They engulf the bacteria
Neutrophils
-Next on the scene after macrophages -Move toward infected or injured areas drawn by chemicals released damaged tissue or by the infectious agent themselves -engulf bacteria
When neutrophils and macrophages engulf necrotic tissue and bacteria they
die. These dead leukocytes along with the tissue fluid and necrotic tissue form pus
Two types of Acquired immunity
-humoral or Beta cell immunity -Cell mediated or T-cell immunity
Humoral Immunity
is promoted by B lymphocytes -B lymphocytes differentiate and mature in the bone marrow and liver -Each B lymphocyte is capable of making a single type of antibody or (immunoglobin), which it displays in the membrane -If the B lymphocyte antibody contacts a match antigen (presented by a macrophage), the B lymphocyte, assisted by a helper T cell, differentiates into plasma cells and memory B cells
Antigen
An antibody recognizes a foreign particle called an antigen
Plasma Cells
-begin synthesizing free antibodies releasing them into the blood -free antibodies may attach their base to mast cells -When an antibody whose base is bound to a mast cell also binds to an antigen, the mast cell releases histamine and other chemicals
Antibodies
-once bound, antibodies may begin a cascade of reactions involving blood proteins that cause the antigen bearing cell to be perforated -the antibodies may mark the antigen for phagocytosis by macrophages and natural killer cells -Antibodies may cause the antigenic substance to agglutinate
Primary Response
-The first time the immune system is exposed to an antigen -Requires 20 days to reach its full potential
Secondary immune response
-Memory B cells proliferate and remain in the body. In the case of reinfection each of these cells can be called upon to synthesize antibodies resulting in a faster acting and more potent affect called the secondary response -Requires 5 days to reach full potential
Cell mediated immunity
-Involves T-lymphocytes Helper T cells, memory T cells, suppressor t cells, killer t cells
T-lymphocytes
-Mature in the thymus -Have an antibody-like protein at their surface that recognizes antigens -Tested against self-antigens. If it binds to a self-antigen the T lymphocyte is destroyed -T-lymphocytes that are not destroyed differentiate into help T cells, memory T cells, suppressor T cells, and killer T-cells
Helper T-cells
Assist in activating B lymphocytes as well as killer and suppressor T cells
Memory T cells
Have a similar function to Memory B cells
Suppressor T cells
Play a negative feedback role in the immune system
Killer T cells
-Bind to the antigen-carrying cell and release perforin, a protein which punctures the antigen carry cell -Can attack many cells because they don’t phagocytize their victims -Responsible for fighting some forms of cancer and attacking transplanted tissue
Overview of Immune system
-Bacteria enters and is engulfed by macrophages and neutrophils. Then the interstitial fluid is flushed into the lymphatic system where lymphocytes wait in the lymph nodes. Macrophages process and present the bacterial antigens to B lymphocytes. With the help of Helter T cells, B lymphocytes differentiate into memory cells and plasma cells. The memory cells are preparation in the event that the same bacteria ever attacks again (the secondary response). The plasma cells produce antibodies which are released into the blood to attack the bacteria.
A single antibody is specific for
a single antigen. A single B lymphocyte produces only one antibody type.
Blood Types
-identified by A and B surface antigens -Type A means the red blood membranes -Having a certain blood type means you don’t make antibodies for those types
Type O blood has neither
A or B antigens so makes A and B antibodies
An individual may donate blood only to a donor whose body does not have
those antigens
Blood donation table. Accepted or rejected
A and B antigens are
Co-dominant
A blood type
IAIA or IAi
B blood type
IBIB or IBi
AB bloodtype
IAIB
O blood type
ii
Rh factors
are surface proteins on red blood cells
Individuals having genotypes that code for nonfunctioning proteins are
Rh Negative
Three types of Muscle tissue
Skeletal muscle
Cardiac muscle
Smooth muscle
Any muscle tissue generates a force only by contracting its cells
Four possible functions:
- Body movement
- Stabilization of body position
- Movement of substances through the body
- Generating heat to maintain body temperature
Skeletal muscle
Voluntary muscle tissue that can be consciously controlled
-Connects one bone to another
Tendon
Connects muscle to bone
Ligament
Connects Bone to Bone
Typically a muscle stretches across a joint and the small bones moves while the large remains stationary
Muscles work in groups
Agonists contracts and antagonists stretch
Synergistic Muscles
Assist the agonist by stabilizing the origin bone or by positioning the insertion bone during the movement. In this way skeletal muscle allows for movement and posture
Contraction of skeletal muscles may squeeze blood and lymph vessels aiding
circulation
Shivering
Creates heat by rapid contractions; stimulated by hypothalamus
Sarcomere
- Smallest functional unit of skeletal muscle
- Composed of thick and thin filaments, laid side by side to form a cylindrical element
- Positioned end to end to form a myofibril
- Each myofibril is surrounded by a specialized endoplasmic reticulum called the sarcoplasmic reticulum
- Lumen of the sarcoplasmic reticulum is filled with Ca2+ ions
- Lodged between myofibrils are mitochondria and many nuclei; skeletal muscle is multinucleated
Thick filament of sarcomere
Made of the protein myosin; several long myosin molecules wrap around each other to form one thick filament
Thin filament of sarcomere
Composed mainly of the polymer actin
Myosin and actin work together sliding alongside each other to create the
contractile force of skeletal muscle
Each myosin head crawls along the actin in a 5 stage cycle
- first tropomyosin covers an active site on the actin preventing the myosin head from binding. The myosin head remains cocked in a high energy position with an ADP and P attached
- in the presence of Ca2+, troponin pulls the tropomyosin back exposing the active site allowing the myosin head to bind to the actin
- the myosin head expels a phosphate and ADP bend into a low energy position dragging the actin along with it. This is the power stroke.
- ATP attaches to the myosin head releasing the myosin head from the active site which is covered immediately by tropomyosin
- ATP splits to P and ADP causing the myosin head to cock into the high energy contraction
T-tubules
- ACh released across the neuromuscular synapse, action potential moves deep into the muscle cell via small tunnels in the membrane called T-tubules
- Allow for uniform contraction of the muscle by allowing the action potential to spread more quickly
- When the AP travels to the sarcoplasmic reticulum it suddenly becomes permeable to Ca2+ ions beginning the 5-stage cycle
Myoglobin
-Oxygen storing protein similar to hemoglobin; stores oxygen inside muscle cells, can only store one molecule of oxygen
Types of Muscle
(oxidative)
Slow oxidative(type I), fast oxidative(type IIA), fast glycolytic (typeIIB)
Slow Oxidative (Type I) Muscle
- red from large amounts of myoglobin
- Lots of mitochondria
- Split ATP at a slow rate so they are slow to fatigue but have slow contraction velocity
Fast Oxidative (Type IIA) muscle
- Red, but split ATP at a fast rate
- Contract rapidly and are resistant to fatigue but not as resistant as type I
Fast Glycolytic (Type IIB) muscle
- Have lower myoglobin content
- Appear white
- Contract rapidly and have a lot of glycogen
Cardiac Muscle
- Is striated meaning its composed of sarcomeres
- Each cardiac muscle cell contains only one nucleus and is separated from its neighbor by an intercalated disc
- Involuntary
- Exhibits a plateau after depolarization that’s created by slow voltage-gated calcium channels which allow calcium to enter and hold the inside of the membrane at a positive potential difference. The plateau lengthens the time of contraction
Intercalated disc
Contains gap junctions which allow an action potential to spread from one cardiac cell to the next via electrical synapses
Smooth muscle
- Involuntary, so it is innervated by the autonomic nervous system
- Contains only one nucleus
- Contains thick and thin filaments but they aren’t organized into sarcomeres
- In addition, smooth muscle cells contain intermediate filaments, which are attached to the dense bodies spread throughout the cell.
- The thick and thin filaments are attached to the intermediate filaments, and, when they contract, they cause the intermediate filaments to pull the dense bodies together. Upon contraction, the smooth muscle cell shrinks length-wise
- SIngle-unit smooth muscle cells are connected by gap junctions spreading the AP from a single neuron through a large group of cells allowing the cell to contract as a single unit.
- Contracts or relaxes in response to hormones, neural stimulus, change in pH, O2 and CO2 levels, temperature, and ion concentrations
Bone
- Bone is living tissue
- Its functions are: support of soft tissue, protection of internal organs, assistance in movement of the body, mineral storage, blood cell production, and energy storage in the form of adipose cells in bone marrow.
- Bone tissue contains three types of cells surrounded by an extensive matrix
Osteoblasts
- Secrete collagen and organic compounds upon which bone is formed
- Incapable of mitosis
- As they release matrix materials around themselves they become enveloped by the matrix and differentiate into osteocytes
Build bone
Osteocytes
- Incapable of mitosis
- Exchange nutrients and waste materials with the blood
A bone cell
Osteoclasts
- Resorb bone matrix, releasing minerals back into the blood
- Develop from white blood cells called monocytes
Break down bone
Spongy Bone
Contains red bone marrow
Site of red blood development
Contact Bone
Contains yellow bone marrow
-Contains adipose cells for fat storage
In a continuous remodeling process osteoclasts burrow tunnels called
Haversian (central) canals through compact bone.
Lamellae
Osteoclasts are followed by osteoblasts that lay down a new matrix onto the tunnel walls forming concentric rings called lamellae
Canaliculi
Osteocytes trapped between the lamellae exchange nutrients via canaliculi
Volkmann’s Canals
Haversian canals contain blood and lymph vessels and are connected bu crossing canals called Volkmann’s canals
Osteon
Entire system of lamellae and Haversian canals
Bone function in Mineral Homeostasis
- Calcium salts are only slightly soluble so most calcium in the blood is not in the form of free calcium ions but is bound by phosphates (HPO4^2-) and other anions. It is the concentration of free calcium ions (Ca2+) in the blood that is important physiologically.
- Too much Ca2+ makes membranes become hypo-excitable producing lethargy, fatigue, and memory loss.
- Too little produces cramps and convulsions
- Most of the Ca2+ in the body is stored in the bone matrix as hydroxyapatite
- Gives bones greater compressive strength
- Bone acts as a storage site for both Ca2+ and HPO4^2-
- Bone helps maintain a consistent concentration of these ions in blood
- Bone also stores energy in the form of fat and is the site of blood cell formation
Cartilage
- Flexible, resilient connective tissue composed primarily of collagen
- Has great tensile strength
Joints
Synovial fluid provides lubrication and nourishment to the cartilage
Important functions of the skin
- Thermoregulation- blood conducts heat from the core of the body to skin. Some of this heat can be dissipated by the endothermic process of evaporation
- Protection
- Environmental sensory input
- Excretion-water and salts
- Immunity- Specialized epidermis cells are components of the immune system
- Blood reservoir-Vessels in the dermis hold 10 % of the blood in a resting adult
- Vitamin D synthesis- UV radiation activates molecules in the skin that is a precursor to vitamin D
Skin is divided into two principal parts
Epidermis and dermis
Epidermis
- 90% of the epidermis is composed of Keratinocytes which produce keratin that helps waterproof the skin
- Melanocytes transfer melanin to keratinocytes
- Langerhands cells interact with the helper T-cells of the immune system
- Merkel cells attach to sensory neurons and function in the sensation of touch
Dermis
- connective tissue derived from mesodermal cells
- Collagen and elastic fibers in the dermis provide skin with strength, extensibility, and elasticity
- Embedded by blood vessels, nerves, glands, and hair follicles
Mendel performed a test cross between
the F1 generation (purple) with the homozygous recessive parent (white). Since there were white offspring resulting from this cross of a purple F1 plant and a white parent plant, Mendel proved the F1 generation was heterozygous
F1 Generation
- The first filial generation
- When F1 was self pollinated F2 expressed both the dominant and recessive traits in 3:1 Mendelian ratio
F2 Generation
-When F2 was self-pollinated 33% produced dominant traits and the rest were the Mendelian ratio. The white-flowered plants produced only white-flowered plants. Thus, half the F2 generation expressed the dominant trait with the recessive trait latent.
Complete dominance
Complete dominance is a form of dominance in heterozygous condition wherein the allele that is regarded as dominant completely masks the effect of the allele that is recessive.
- A diploid individual will have two chromosomes each containing a separate gene that codes for a specific trait
- Locus-the corresponding genes are located at the same locus, or position, on the respective chromosome
Law of Segregation
- States that alleles segregate independently of each other when forming gametes
- Any gamete is equally likely to express any allele
Inbreeding
-Doesn’t change the frequency of alleles but does increase the number of homozygous individuals within a population
Law of Independent Assortment
- Genes located on different chromosomes assort independently of each other
- If two genes are located on the same chromosome the likelihood that they will remain together during gamete formation is indirectly proportional to the distance separating them
Phenotypic ratio of a dihybrid cross
9:3:3:1
23rd pair of chromosomes establishes the sex of the individual and each partner is called
a sex chromosome.
23rd chromosome of a man is abbreviated as a Y instead of an X
-Generally the allele is carried on the X and not the Y. In the female who has two X chromosomes one will condense and become a Barr body, rendering its genes inactive
Barr bodies are formed at
random and so the active allele is split about evenly among cells.
Carrier
the female may carry a recessive trait on her 23rd pair without expressing it. Such a trait has a large chance of being expressed in her male offspring regardless of the genotype of her mate
Karyotype
A map of chromosomes
Gene Pool
Total of all alleles in a population
Evolution
Change in the gene pool
Classification order
Kingdom, Phylum, Class, order, family, genus, species
Plant and Fungi use division instead of phylum
Phylum chordata—> sub phylum vertebrata
All mammals belong to the class and the phylum_______
Class mammalia and phylum chordata
Domains
Bacteria, Archaea, Eukarya
Coacervates
lipid or protein bilayer bubbles; grow randomly from fat in water
Species
Loosely limited to but not inclusive of all organisms that can reproduce fertile offspring with each other
Niche
- The way in which a species exploits its environment
- No two species can exploit a niche indefinitely
Survival of the fittest- says one species will exploit the niche more efficiently
r-selection
-large number of offspring with little or no parental care; have a high brood mortality rate
K-selection
Sigmoidal growth curve that levels off at the carrying capacity
Speciation
- Process by which new species are formed
- When gene flow stops between two sections of a population speciation begins
Adaptive Radiation
-Occurs when several separate species arise from a single ancestral species
Evolutionary Bottleneck
-If a species faces a crisis so severe as to cause a shift in the allelic frequencies of the survivors of the crisis
Divergent evolution
-When two or more species evolving from the same group maintain a similar structure from the common ancestor
Convergent evolution
When two species evolve similar structures with no common ancestry
Polymorphism
Occurrence of distinct forms such as tall/short, flower color, etc.
Hardy-Weinberg Equilibrium
Large Population
Mutational Equilibrium-rate of forward mutations equal to rate of back mutations(not true)
Immigration or Emigration must not change the gene pool
Random Mating
No Selection for Fittest Organism
Hardy-Weinberg Equilibrium
p^2+ 2pq + q^2
P+Q = 1
P is dominant, Q is recessive
Probability that two p’s come together is p^2
Probability that a ‘p’ and a ‘q’ come together is 2pq
Probability that 2 q’s come together is q^2
Chordata
- A phylum containing humans
- All chordates have bilateral symmetry
- At some stage in development they possess a notochord, pharyngeal slits, a dorsal, hollow nerve cord, and a tail
Deuterostomes
-All chordates are these; anus develops from or near blastopore
Coelom
Chordates have these; body cavity with mesodermal tissue
Vertebrata
- have their notochord replaced by a segmented cartilage and bone structure
- Have a distinct brain enclosed in a skull
