chapter 8

Question 1

what is the difference between gonads and genitalia?

Answer 1

• gonads are the specific organs in which gametes are made: testes and ovaries
• genitalia refers to the reproductive organs (the external organs)

Question 2

what is the function of the scrotum and the testes?

Answer 2

• a pouch that hands behind the penis and it contains the testes where sperm is produced but also secretes hormones like testosterone

Question 3

what temperature does spermatogenesis function?

Answer 3

• a few degrees below body temperature

Question 4

the core of the testis is made up by the?

Answer 4

• seminiferous tubules and meiosis and spermatogenesis occur there

Question 5

what cells are present in the seminiferous tubules?

Answer 5

• germ cells and sertoli cells which constituse the epithelium of the seminiferous tubules and they help germ cells develop into spermatozoa

Question 6

what are Leydig cells?

Answer 6

• cells found adjacent to the seminiferous tubules, they are linked to endocrine function of the testes and secrete androgens (male sex hormones) such as testosterone

Question 7

immature spermatozoa made in the seminiferous tubules move to the?

Answer 7

• epididymis- used for the storage and further maturation of spermatozoa

Question 8

in the event of ejaculation, spermatozoa move from the epididymis to the?

Answer 8

• vas deferens, the tube that connects the epididymis to the ejaculatory ducts

Question 9

the ejaculatory ducts are formed by a fusion of the vas deferens with the?

Answer 9

• seminal vesicles that generate most of the liquid component of semen (fructose, vitamins, enzymes, and other proteins necessary for spermatozoa to stay alive after ejaculation)

Question 10

the ejaculatory ducts run through the?

Answer 10

• prostate glands and then join with the urethra

Question 11

what are the Cowpers glands?

Answer 11

• secretions known as pre-ejaculate travel through these glands to lubricate the urethra and neutralizes any remaining acidic urine that is present

Question 12

what is the difference bewteen sperm and semen?

Answer 12

• sperm are the haploid gametes with flagella that can fertilize an egg
• semen is the alkaline liquid containing nutrients that they are carried in

Question 13

what is the internal and external parts of the female reproductive tract?

Answer 13

• internal genitalia include the ovaries, fallopian tubes, uterus, cervix and vagina
• external genitalia are known as the vulva which includes the labia majora, labia minora, clitoris and vaginal opening

Question 14

what are the ovaries?

Answer 14

• the female gonads and where oogenesis takes place, resulting in mature egg cells

Question 15

what are the fallopian tubes?

Answer 15

• they connect the ovaries to the uterus
• they have a smooth muscle layer that carries out peristalsis muscle contractions that push contents through a tube
• they have an abundance of ciliated cells

Question 16

what is the uterus?

Answer 16

• where the fetus develops during pregnancy
• its innermost layer is composed of epithelial cells and a mucous membrane known as the endometrium
• its middle layer consists of smooth muscle and is known as the myometrium
• the lower part of the uterus is known as the cervix

Question 17

what is spermatogenesis and its steps?

Answer 17

• the processes through which gametes (sperm) are generated
  
  • begins with spermatogonial stem cells and ends with mature spermatozoa
    
    • spermatogonial stem cells can either divide into descendent spermatogonialstem cells or differentiate into speramtogonia
      
      • spermatogonia divide through mitosis into 2 primary spermatocytes
        
        • primary spermatocytes go through meiosis I and divide into secondary spermatocytes (diploid to haploid occurs)
        • secondary spermatocytes then go through meiosis II forming spermatids which lack important features mature sperm cells have but gain those in spermiogenesis
      • spermiogenesis events are formation of the acrosomal cap, formation of a tail and loss of excess cytoplasm and results in non-mature spermatozoa that are incapable of independent movement and are transferred to the epididymis to undergo maturatuin

Question 18

what is the process of oogenesis and its steps?

Answer 18

• produces gametes (ova)
  
  • begins with oogonia, which are formed from primordial germ cells in a process known as gametogenesis
    
    • oogonia differentiate into primary oocytes and then they undergo meisosi 1 and become secondary oocytes, but this process is halted in prophase 1
    • menarche (the first mentral cycle) marks the resumption of oogenesis but only a few cells at a time
    • the ocum that is released during ovulation completes meiosis 1 and results in 1 secondaty oocyte along with one polar body
    • the secondary oocyte goes through meiosis 2 but are frozen at metphase 2 until fertilization while the polar body whithers away

Question 19

how does fertilization take place?

Answer 19

• takes place in the Fallopian tube
  
  • sperm cell has to encounter a secondary oocute
  • as the sperm cell approaches the secondary oocyte, it passes through the corona radiata which comprises a layer of folliculare cells surrounding the oocyte
  • next it passes through the zona pellucida which is a layer of glycoprotiens between the corona radiata and the oocyte
  • one of the glycoproteins binds with the sperm head and triggers the acrosome reaction in which digestive enzymes are released that all the nucleus of the sperm to enter the egg
  • the glycoprotiens of the zona pellucida form cross-linked structures that pervent another sperm from fertilizing the egg (cortical reaction) and the secondary oocyte completes meiosis II, creating a second polar body and a mature ovum
  • then the haploid nuclei of the sperm cell and the ovym merge, creating a dipoloid, one-cell zygote

Question 20

upon the creation of a diploid, one cell zygote, the zygote must?

Answer 20

• travel from the Fallopian tubes to the uterus for future development
  
  • extopic pregnancy occurs if development occurs in the Fallopian tube, in the abdomen, the cervix or in the ovaries
    
    • ectopic pregnancies almost never lead to viable fetuses

Question 21

as the zygote travels to the uterys,it undergoes a series of mitotic cell divisions known as?

Answer 21

• cleavage
  
  • as soon as cleavage takes place, the zygote is considered to be transformed into an embryo
• during cleavage, the overall size of the embryo does not change: more and more cells are being created, but they are contained within the same space, meaning that the cells are smaller than the original zygote and that the nuclear-to-cytoplasmic (N:C) ratio increases

Question 22

once the zygote has cleaved into a mast of 16 cells by 3 to 4 days after fertilization, it is known as?

Answer 22

• the morula

Question 23

by 3 to 5 days after fertilization, the morula develops into?

Answer 23

• a blastocyst (the more general term for multicellular organisms)
  
  • characterized bty a fluid-filled cavity in the middle known as the blasteocoel
    
    • a U shpaed protrusion pokes into part of the blastocoel known as the inner cell mass which eventually develops into the fetus. the other cells surrounding the blastocoel are known as the trophoblast and eventually genarate the placenta

Question 24

the blastocyst then implants in the?

Answer 24

• uterine endometrium

Question 25

implantation is?

Answer 25

• a multi-stage process that involves the communication and adaptation between the embryo and the uterine tissue
  
  • the placenta begins to form form the trophoblast and the chorion and amnion begin to form from parts of the internal cell mass
    
    • the chorion envelops the embryo/fetus throughout pregnancy

Question 26

once implanted, the embryo further differentiations into the?

Answer 26

• gastrula
  
  • has 3 layers
    
    • ectoderm, mesoderm and endoderm which eventually go on to form specific organs and components of the body

Question 27

what does the ectoderm give rise to?

Answer 27

• primarily gives rise ot the nervous system (neurulation) and epidermis, as well as related structures like hair, nails and sweat glands

Question 28

what are the steps of neurulation?

Answer 28

• formation of a rod of mesodermal cells known as the notochord, which includes the formation of the neural plate in the ectodermal tissue located above it
• the neural plate folds upward, with the neural folds on the side and the neural groove in the middle
• the folding process continues, and the neural folds eventually meet at which they form the neural tube
• the neural tube goes on to form the CNS, while the neural crest cells initially located on the neural folds form the PNS
• at the end of this process, the surface ectoderm surrounds the neural tube, such that the CNS can develop within the body

Question 29

what does the mesoderm genarate?

Answer 29

• many of the structures present within the body including the masculature, connective tissue (including blood bone and cartilage), the gonads, the kidneys, and the adrenal cortex

Question 30

what does the endoderm genarate?

Answer 30

• responsible for the interior linings of the body, including the linings of the GI system, the pancreas and part of the liver, the urinary bladder, and part of the urethra and the lungs

Question 31

summary of what the layers give rise to in a fetus?

Answer 31

Question 32

what happens throughout the trimesters of pregnancy?

Answer 32

• throughout the first trimester, the major organs develop in a process nown as organogenesis
• in the second and third trimesters, the fetus grows larger and develops further

Question 33

what is the function of the placenta?

Answer 33

• allows for nutrients, gases, and waste products to be exchanged through a combination of passive and active transport
• the placenta secretes human chorionic goandotropin (hCG) early in pregnancy and later in pregnancy secretes progesterone and estorgen

Question 34

fetal hemoglobin has a?

Answer 34

• higher affinity for oxygen than adult hemoglobin, this fact allows oxygen to be “passed” more efficiently from the maternal circulation to the fetal circulation

Question 35

the fetus is connected to the placenta through the?

Answer 35

• umbilical cord

Question 36

sexual differentiation takes place?

Answer 36

before birth in the fetuses

Question 37

SRY causes the development os testes, which secrete hormones that cause the precursor structures of the?

Answer 37

• Wollfian duct and Mullerian duct
  
  • in male fetuses, the Wolffian duct differentiates into accessroy organs of the male reproductive system while the Mullerian duct is lost
  • In females, the Wolfian duct regresses and the Mullerian duct develops into the female reproductive system

Question 38

Pregnancy usually lasts between 37-41 weeks and comes to an end with labor and childbirth which is called?

Answer 38

• parturition

Question 39

What is the ovarian cycle?

Answer 39

• begins with the follicular phase, followed by ovulation, which is in turn followed by the luteal phase (what happens after the ovum is release; the follicle is trnasformed into a structure known as the corpus luteum, which secretes progesterone, helping to maintain the uterine lining. the corpus luteum decays towards the end of this period and another cycle begins)
  
  • (follicular phase- follicle develops, ovulation- egg is released, luteal phase- follicle → corpus luteum)

Question 40

what is the uterine cycle?

Answer 40

• begins with menstruation, which overlaps with the first part of the follicular phase of the ovarian cycle
• during menstruation, the uterine lining built up in the previous cycle is sloughed off
• once menstruation is completem the uterine endometrium is built up again during the proliferative phase
• the final phase of the uterine cycle is known as the secretory phase and this overlaps with the luteal phase of the ovarian cycle. during this phase, the uterine endometrium continues to build up and undergoes various changes to make ot more receptive for implantation, under the influence of the progesterone secreted by the corpus luteum
  
  • (mensturation- uterine endometrium from previous cycle sheds, prolferative phase- endometrium develops again, secretory phase- endoemtrium is ready for implantation)

Question 41

hormones at play in the ovarian and uterine cycle?

Answer 41

• at the beginning of the follicular phase, there is a moderate rise in FSH which induces follicular development before gradually dropping off
• throughout most of the follicular phase, estrogen levels gradually increases, stimulating the development of the uterine endometrium
• after estrogen levels reach a certain threshold close to ovulation, they stimular a brief syrge in LH and FSH levels. the LH spike triggers ovulation and induces the transformation of teh follicle into the corpus luteum
• the luteal phase is characterized by high levels of progesterone, which help maintain the readiness of the uterine endometrium for implantation

Question 42

how does the body know whether or not implantation has taken place, and therefore whether to transtition into another menstraul cycle or into pregnancy?

Answer 42

• in the absence of implantation, successive negative feedback loops keep the cycle moving
• if implantation occurs, the embryo secretes a hormone known as human chorionic gonadotropin (hCG) which allows the corpus luteum to be maintained and for progesterone levels to be sustained
  
  • by the 2nd trimester, hCG levels drop and the placenta can function as an endocrine organ and independently secrete progesterone and estrogen