Reproductive system

Question 1

What are sustentacular cells?

Answer 1

sustentacular cells are aka Sertoli cells which are responsible for spermatogenesis. They also produce androgen-binding-protein (ABP) which grabs synthesized testosterone

they are responsive to FSH

Question 2

what are interstitial cells?

Answer 2

interstitial cells are aka Leydig cells which produce androgens namely testosterone which diffuses to sustentacular cells

Question 3

what do the seminal vesicles, bulbourethral glands, and prostate produce?

Answer 3

SV –> fructose (60% of sperm)
BG –> aka cowpers glands –> alkaline mucous
prostate –> alkaline mucous and coagulant

Question 4

the 3 stages of the male sex act are 1. arousal 2. orgasm 3. resolution. Explain the nervous system activity in each

Answer 4

1. During arousal, erection + lubrication is accomplished by the PNS
2. During orgasm, emission + ejaculation by SNS
3. During Resolution, vasoconstriction by SNS

Question 5

Spermatogenesis occurs in seminiferous tubules where young sperm cells start on the basolateral layers of the sustentacular cells. As they mature they move towards the tubule lumen where they eventually deposit and go to the epididymis. Explain the different stages of spermatogenesis.

Answer 5

Outer layer of tubules
1. Spermatogonia (2n,2x)
these undergo mitosis where one stays and one leaves
2. primary spermatocyte: undergo meiosis 1
3. secondary spermatocyte: undergo meiosis 2
4. spermatid (1n,1x) : undergo maturation
5. spermatozoa: go to epididymis

Question 6

what is the hormone inhibin? what is it secreted by?

Answer 6

LH stimulates leydig cells to produce tesosterone

FSH stimulates sertoli cells for spermatogenesis
- sertoli cells in response release inhibin which acts on the anterior pituitary to inhibit the release of FSH

Question 7

true or false, estrogen, progesterone, and testosterone all exhibit negative feedback on the AP.

Answer 7

true, along with inhibin. As a result, high levels of testosterone in the blood will cause a reduction in secretion of FSH and LH

Question 8

Explain embryonic development of an XY baby? i.e. hormone production and development of internal / external reproductive tracts.

Answer 8

the female reproductive tract is default. Therefore, in the absence of testosterone and mullerian inhibiting factor, the mullerian ducts develop (cervix, uterus, fallopian tubes) and external female genitalia.

If a baby is XY, the y chromosome leads to testes development (H-Y antigen). Synthesized testosterone allows for the development of external male genitalia. The testes also produce mullerian inhibiting factor (MIF) which allows the wolffian ducts to develop instead. Note the wolffian duct development also requires testosterone stimulation

Question 9

what must testosterone be converted too in order for it to produce male external genitals?

Answer 9

testosterone must be converted to dihydrotestosterone first! the wolffian duct (internal male tract) only requires testosterone

Question 10

true or false, testosterone and estrogen cause epiphyseal plate closure

Answer 10

true, this is why precocious puberty creates shorter people

Question 11

what is GnRH

Answer 11

gonadotropin releasing hormone released from the hypothalamus through the hypophyseal portal system to the AP where FSH and LH are released.

Question 12

explain the process of oogenesis starting from the mitotic divisions in utero (the fetus).

Answer 12

for the first have of gestation, the fetus oogonia divide mitotically. They then start meiosis 1 till prophase = primary oocyte

2. Upon puberty, the primary oocyte ovulates and completes meiosis 1 now becoming the haploid secondary oocyte (+first polar body)
3. If fertilization occurs, the secondary oocyte performs meiosis 2 to become the ootid and then the ovum (+second polar body)

Question 13

Why is the primary follicle aka primordial follicle

Answer 13

the primary / primordial follicle is the primary oocyte surrounded by a layer of granulosa cells.

Question 14

as the primordial follicles mature in preparation for ovulation, the granulosa cells divide giving more layers.. additionally the oocyte produces a protective layer around it. What are these two layers called.

Answer 14

the follicular layer is called the corona radiata

The protective layer is the Zona pellucida

Question 15

only one follicle will ovulate. what is the name of this follicle and what happens to it during ovulation

Answer 15

This is the Graafian follicle. Upon ovulation, the now secondary oocyte burst out of the follicle bringing with it its zona pellucida and corona radiata. The follicular cells it leaves behind become the corpus luteum while all other primary follicles undergo atresia.

Question 16

Explain the granulosa cell and theca cell relationship

Answer 16

surrounding each oocyte is the granulosa cells. inbetween the follicles are the theca cells.

Upon LH stimulation, theca cells produce androgens derived from cholesterol. These diffuse outward towards the follicles. The androgens are picked up by the granulosa cells which use the enzyme aromatase to convert androgen to estrogen. This is aided by FSH stimulation.
The corpus luteum takes over after ovulation

Question 17

what is the difference between the menstrual, ovarian, and uterine cycles?

Answer 17

the menstrual cycle explains the entire reproductive cycle of a female including ovarian and uterine cycles

ovarian: follicular, ovulation, luteal
uterine: menstruation, proliferative, secretory

Question 18

Explain whats occurring in the follicular, ovulatory, and luteal phases of the ovarian cycle. (hormones, eggs, time, etc.)

Answer 18

1. follicular phase (1-13) –> primary follicles mature and secrete estrogen. maturation of the “Graafian follicle” is controlled by FSH
2. Ovulation (14) –> release of the secondary oocyte triggered by the LH surge
3. Luteal phase –> corpus luteum takes over E and P production. These hormones maintain the uterus.

Question 19

Explain the menstruation, proliferative, and secretory phase of the uterine cycle.

Answer 19

1. Menstruation (5 days) –> the denergation of the corpus luteum causes E and P levels to drop. the endometrium looses its nourishment and sloughs off.
2. Proliferative phase (9 days) –> regeneration of the endometrium which is aided by the follicular stage primary follicles producing estrogen
3. Secretory phase (14 days) –> E and P from corpus luteum cause the endometrium to secrete glycogen and other nutrients for the blastocyst.

Question 20

note: LH maintains the corpus luteum so why does it degrade at all?

Answer 20

the high levels of estrogen the CL is making inhibits the anterior pituitary to release more LH.

Question 21

what occurs if estrogen and progesterone levels are kept artificially high an entire month ?

Answer 21

the woman would not ovulate (no LH surge) also she wouldn’t normally have menstruation

Question 22

what is hCG?

Answer 22

high levels of estrogen inhibit further LH and FSH release. This is important since, if pregnancy occurs, this prevents ovulation occurring. However, the lack of LH means the CL will degrade.

If pregnancy does occur, upon implantation the chorion develops (the portion of the placenta made by the zygote) which produces human chorionic gonadotropin. This maintains the CL instead of LH.

Question 23

what is capacitation

Answer 23

the final maturation of sperm where the inhibitory enzymes of semen dilute out in the vagina

Question 24

what is the cortical reaction?

Answer 24

after one sperm penetrates the secondary oocyte an influx of calcium causes changes to the zona pellucida which prevents other sperm from binding

Question 25

once the zygote has formed, what happens to it from this stage up until implantation?

Answer 25

the zygote undergoes many mitotic divisions to become the morula (note the morula is the same size as the zygote indicating the mitosis skipped G1 and G2 phases)

as it moves to the uterus, the morula differentiates into the blastocyst which contains trophoblasts and an inner cell mass.

Question 26

explain the blastocysts trophoblasts and inner cell mass

Answer 26

trophoblasts will become the chorion after aiding in implantation by releasing proteases. The inner cell mass will become the embryo

Question 27

What is the process called cleavage?

Answer 27

the consecutive mitosis of the zygote into the morula

Question 28

during the first trimester of gestation what supports the endometrium. What about in the last two trimesters?

Answer 28

first trimester –> hCG from the chorion stimulates the corpus luteum which keeps P and E high

second two –> placenta develops which secretes its own P and E

Question 29

The embryo is actually one of 4 structures that come from the inner cell mass. there is also the 
amnion 
yolk sac 
allantois 
explain each

Answer 29

amnion –> fluid cavity that contains the fetus in the uterus
yolk sac –> important in other animals to provide nourishment. For humans it is the first site of embryonic RBC synthesis (hematopoiesis)
allantois –> develops from the embryo to make the vessels of the umbilical cord

Question 30

what is blastulation, gastrulation, and neurulation?

Answer 30

blastulation is the differentiation of the morula into the blastocyst. gastrulation is when the three primary germ layers of an organism (endo,meso,ecto derms) become present. Neurulation is one of the first organogenesis processes in which the ectoderm develops the nervous system.

Question 31

what is the actual process of gastrulation?

Answer 31

essentially, the ball of cells of the inner cell mass fold inward on themselves developing three distinct layers. The inner most being the endoderm and outermost being the ectoderm.

Question 32

what is the embryonic disk?

Answer 32

this is the term given to the structure that undergoes gastrulation (inner cell mass)

Question 33

What are three major organs/systems/body parts that come from the: Ectoderm

Answer 33

1. Nervous system
2. epidermis of skin + derivatives (hair, nails)
3. cornea and lens

Question 34

What are three major organs/systems/body parts that come from the: mesoderm

Answer 34

1. all muscle, bone, and connective tissue
2. cardiovascular system
3. urogenital organs (kidneys, gonads, etc)

Question 35

What are three major organs/systems/body parts that come from the: endoderm

Answer 35

1. GI tract and respiratory tract epithelium
2. GI glands
3. bladder

Question 36

after 8 weeks, what is the embryo called? What is partially complete?

Answer 36

8 weeks in, organogenesis has made all major organs present and now the embryo is called the fetus

Question 37

Explain Totipotent, pluripotent, and multi-potent cells! What about embryonic stem cells?

Answer 37

Totipotent cells can literally become any cell within fetal development. These are the morula and zygote cells which can become inner cell mass or trophoblasts (i.e. the placenta)

Pluripotent cells are cells that can differentiate into any of the three germ layers. These are inner cell mass cells also called embryonic stem cells.

multi potent cells can become a many but not all human cells. These are specifically ectoderm or mesoderm or endoderm cells.

totipotent –> pluripotent –> multipotent –> differentiated

Question 38

what is the difference between determination and differentiation?

Answer 38

at a certain point, a cell becomes destined to become a certain cell type. At this point, its job has been determined but it has not differentiated yet.

Question 39

what is dangerous of dedifferentiation

Answer 39

dedifferentiation can be a result of cancer in which cells are induced to dedifferentiate and divide uncontrollably

Question 40

what are two cell types in the body that do not have identical genomes to the rest of the body?

Answer 40

1. B and T cells undergo gene recombination to amplify antigen possibilitiese
2. gametes

Question 41

explain the positive feedback during parturition.

Answer 41

as pregnancy continues, uterine contractions become more excitable and rhythmic. This causes increased pressure on the cervix. This mechanical disturbance causes oxytocin to be released from the posterior pituitary which causes increased contractions

Question 42

how does estrogen and progesterone effect prolactin?

Answer 42

E and P inhibit prolactin release which is needed for milk production. they do stimulate mammary gland development but not milk production

Question 43

what occurs in lactation and breastfeeding.

Answer 43

after birth, low E and P allow for prolactin release which causes milk production in mammary glands. Then upon sucking stimulus, oxytocin is released which contracts mammary glands to eject milk. This is also a positive feedback loop.