Reproductive system Flashcards
What are sustentacular cells?
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
what are interstitial cells?
interstitial cells are aka Leydig cells which produce androgens namely testosterone which diffuses to sustentacular cells
what do the seminal vesicles, bulbourethral glands, and prostate produce?
SV –> fructose (60% of sperm)
BG –> aka cowpers glands –> alkaline mucous
prostate –> alkaline mucous and coagulant
the 3 stages of the male sex act are 1. arousal 2. orgasm 3. resolution. Explain the nervous system activity in each
- During arousal, erection + lubrication is accomplished by the PNS
- During orgasm, emission + ejaculation by SNS
- During Resolution, vasoconstriction by SNS
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.
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
what is the hormone inhibin? what is it secreted by?
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
true or false, estrogen, progesterone, and testosterone all exhibit negative feedback on the AP.
true, along with inhibin. As a result, high levels of testosterone in the blood will cause a reduction in secretion of FSH and LH
Explain embryonic development of an XY baby? i.e. hormone production and development of internal / external reproductive tracts.
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
what must testosterone be converted too in order for it to produce male external genitals?
testosterone must be converted to dihydrotestosterone first! the wolffian duct (internal male tract) only requires testosterone
true or false, testosterone and estrogen cause epiphyseal plate closure
true, this is why precocious puberty creates shorter people
what is GnRH
gonadotropin releasing hormone released from the hypothalamus through the hypophyseal portal system to the AP where FSH and LH are released.
explain the process of oogenesis starting from the mitotic divisions in utero (the fetus).
for the first have of gestation, the fetus oogonia divide mitotically. They then start meiosis 1 till prophase = primary oocyte
- Upon puberty, the primary oocyte ovulates and completes meiosis 1 now becoming the haploid secondary oocyte (+first polar body)
- If fertilization occurs, the secondary oocyte performs meiosis 2 to become the ootid and then the ovum (+second polar body)
Why is the primary follicle aka primordial follicle
the primary / primordial follicle is the primary oocyte surrounded by a layer of granulosa cells.
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.
the follicular layer is called the corona radiata
The protective layer is the Zona pellucida
only one follicle will ovulate. what is the name of this follicle and what happens to it during ovulation
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.
Explain the granulosa cell and theca cell relationship
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
what is the difference between the menstrual, ovarian, and uterine cycles?
the menstrual cycle explains the entire reproductive cycle of a female including ovarian and uterine cycles
ovarian: follicular, ovulation, luteal
uterine: menstruation, proliferative, secretory
Explain whats occurring in the follicular, ovulatory, and luteal phases of the ovarian cycle. (hormones, eggs, time, etc.)
- follicular phase (1-13) –> primary follicles mature and secrete estrogen. maturation of the “Graafian follicle” is controlled by FSH
- Ovulation (14) –> release of the secondary oocyte triggered by the LH surge
- Luteal phase –> corpus luteum takes over E and P production. These hormones maintain the uterus.
Explain the menstruation, proliferative, and secretory phase of the uterine cycle.
- Menstruation (5 days) –> the denergation of the corpus luteum causes E and P levels to drop. the endometrium looses its nourishment and sloughs off.
- Proliferative phase (9 days) –> regeneration of the endometrium which is aided by the follicular stage primary follicles producing estrogen
- Secretory phase (14 days) –> E and P from corpus luteum cause the endometrium to secrete glycogen and other nutrients for the blastocyst.
note: LH maintains the corpus luteum so why does it degrade at all?
the high levels of estrogen the CL is making inhibits the anterior pituitary to release more LH.
what occurs if estrogen and progesterone levels are kept artificially high an entire month ?
the woman would not ovulate (no LH surge) also she wouldn’t normally have menstruation
what is hCG?
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.
what is capacitation
the final maturation of sperm where the inhibitory enzymes of semen dilute out in the vagina
what is the cortical reaction?
after one sperm penetrates the secondary oocyte an influx of calcium causes changes to the zona pellucida which prevents other sperm from binding
once the zygote has formed, what happens to it from this stage up until implantation?
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.
explain the blastocysts trophoblasts and inner cell mass
trophoblasts will become the chorion after aiding in implantation by releasing proteases. The inner cell mass will become the embryo
What is the process called cleavage?
the consecutive mitosis of the zygote into the morula
during the first trimester of gestation what supports the endometrium. What about in the last two trimesters?
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
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
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
what is blastulation, gastrulation, and neurulation?
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.
what is the actual process of gastrulation?
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.
what is the embryonic disk?
this is the term given to the structure that undergoes gastrulation (inner cell mass)
What are three major organs/systems/body parts that come from the: Ectoderm
- Nervous system
- epidermis of skin + derivatives (hair, nails)
- cornea and lens
What are three major organs/systems/body parts that come from the: mesoderm
- all muscle, bone, and connective tissue
- cardiovascular system
- urogenital organs (kidneys, gonads, etc)
What are three major organs/systems/body parts that come from the: endoderm
- GI tract and respiratory tract epithelium
- GI glands
- bladder
after 8 weeks, what is the embryo called? What is partially complete?
8 weeks in, organogenesis has made all major organs present and now the embryo is called the fetus
Explain Totipotent, pluripotent, and multi-potent cells! What about embryonic stem cells?
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
what is the difference between determination and differentiation?
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.
what is dangerous of dedifferentiation
dedifferentiation can be a result of cancer in which cells are induced to dedifferentiate and divide uncontrollably
what are two cell types in the body that do not have identical genomes to the rest of the body?
- B and T cells undergo gene recombination to amplify antigen possibilitiese
- gametes
explain the positive feedback during parturition.
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
how does estrogen and progesterone effect prolactin?
E and P inhibit prolactin release which is needed for milk production. they do stimulate mammary gland development but not milk production
what occurs in lactation and breastfeeding.
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.
