Reproductive Flashcards
Testosterone is synthesized in …… & …..
testes and adrenal gland (zona reticularis)
The testes can not synthesize glucocorticoids because ……..
they lack the enzyme 11 beta hydroxylase (and 21 hydroxylase)
How is Androgen formed from cholesterol??
- Cholesterol is converted to pregnenolone (mitochondria, by 20-22 desmolase)
- pregnenolone is converted to DHEA (dehydroepiandrosterone, by 17-20 desmolase)
- DHEA is converted to androstenodione (by 3 beta HSD)
- Androstenodione is converted to Testosterone (by 17 beta HSD)
* This occur in both the adrenal and the testes
Sex hormone binding globulin is …
SHBG method of transporting sex hormone in blood. Binds testosterone, estradiole, dihydrotestosterone (DHT)
The half life of testosterone is ….
90 mins
Testosterone is activated to …. in some tissues
DHT
- prostate, hair follicles, external genitalia
- DHT binds to nuclear receptors to activate mRNA transcription
Initiation of speamatogenesis in …… cells is influenced by …… & …..
Sertoli
FSH & testosterone
* Paracrine effect
Testosterone is needed in high levels for functioning of ….., ….. & …..
epididymis, vas deferens, seminal vesicles
The prostate needs …… for growth and secretion
DHT
DHT is required in the scrotum for ….. , and also penis …..
rugation (to cool testes)
enlargement at puberty
BPH is caused by …. in elderly
DHT
Sebaceous glands activity is increased by ….
androgens at puberty
The most potent anabolic hormone is ……
testosterone
* it increases protein synthesis and muscle mass
Testosterone in both sexes is the cause of growth spurts by acting on …..
androgen receptors in the end plates of long bones (direct effect)
* Indirect effect is by stimulating GH secretion
Although androgens encourage bone growth, it has a paradoxical effect by …..
stimulate the closing of the epiphyseal plates (end plates), thus limiting growth
LH activates ….. to produce testosterone
Leydig cells
FSH activates Sertoli cells to synthesize and release …..
androgen binding protein
* same as SHBG
what is the role of testosterone in spermatogenesis ??
stimulates the seminiferous tubules and synergizes with FSH to initiate and maintain spermatogenesis
Testosterone inhibits …… secretion from the pituitary, and ….. from hypothalamus
LH (testosterone is converted to estradiole before inhibition, catalyzed by aromatase)
GnRH
Inhibin function is ……
feedback to the pituitary to block the synthesis of FSH & GnRH (in both sexes)
Sperms released from the seminiferous epithelium are …..
non motile nor fertile at this stage
What is the forward motility factor??
A protein formed in the epididymis that acts with testosterone on the sperm to activate its motility, however, it is still non fertile at this stage
* non motile sperm moves in the epididymis by peristalsis
Muscular contractions within …… drive the sperms through the rest of the male urethra
vas deferens
Sperms can survive in the epididymis for up to ….. days
40
Most of the seminal fluid is from ……, the rest is from ….. . It contains …… & …..
seminal vesicles, prostate
* Seminal fluid contains fructose (oxidative substrate for sperms) and Prostoglandin (helps in the induction of contractions in the uterus to propel the the sperm forward)
Sperms are drawn out of …… when seminal fluid is rushed out the terminal opening of vas deferens
vas deferens
Progesterone and estrogen are both found in males. T/F ??
true
Theca interna binds …. , which stimulates the production of ….. from ….. .
Androgen secreted from theca cells are carried to ….. & …..
LH
pregnenolone
cholesterol
the blood & granulosa cells
Under the influence of ……, granulosa cells convert androgen to …… by …… activity
FSH, estrone then to estradiole, aromatase
* FSH also stimulates the formation of LH receptors on the granulosa cells (this occurs upon ovulation. Before that, they lack 17-hydroxylase activity and cannot synthesize estrogen themselves)
Corpus luteum is composed of ….. & ….. . It has the ability to produce …… & …..
theca interna & granulosa cells
estrogen and progesterone
Testosterone and estradiol both can bind to ….., while progesterone binds to ……..
SHBG
corticosteriod binding globulin (also called transcortin, which also binds cortisol and aldosterone)
Steroid hormones bind to …… which migrates to the nucleus to promote …..
cytoplasmic receptor
transcription
Estrogen effects on females are …..
- Breast, clitoral & labial growth
- Ovulation
- Increase oxytocin receptors in fallopian tubes (for contraction)
- Increase blood flow to uterus & endometrial growth
- Thickens vaginal mucosal lining
Estrogens, like androgens are anabolic hormones. T/F??
True
* also responsible for growth spurt and epiphyseal closure
Postmenopausal women are given estrogen to ……
inhibit bone resorption (osteoporosis)
Estrogen …. HDL, ….. LDL
increase
decrease
Estrogen is responsible for fat deposition in females. T/F??
true
* around the hips & breasts
Progesterone effects are ….. & …..
further proliferation of endometrium (after estrogen)
counteracts the action of estrogen in sensitizing the uterus for muscular contraction
In the follicular phase, progesterone falls and releases its ….
its inhibitory effect on hypothalamus. GnRH increase, leading to LH & FSH increase
Increased estrogen levels at the end of follicular phase causes ……. . While in the midcycle, high levels causes ….
suppression of FSH release
surge in both FSH & LH release
Ovulation is caused by ……
high level of estrogen with LH
* LH weakens the follicle wall and causing it to rupture.
In the luteal phase, ….. .is secreted in high levels, while ….. & ….. levels fall
progesterone
LH & FSH
* progesterone level increase is due to neovascularization of the corpus luteum
Progesterone inhibits ….. release
GnRH
* although estrogen level are also high, GnRH is more inhibited by progesterone
If luteolysis occurs, ….. & ….. levels decrease
progesterone & estrogen
* the uterus lining shed and menstrual period begins
Basal body temperature is increased due to high level of ……. during the luteal phase
progesterone
What is the effect of high ratio of estrogen/progesterone ??
increase oxytocin receptors in the fallopian tubes to induce motility, also increase the sweeping action of the fimbriae to capture the egg
* The ratio is high in the follicular phase and midcycle
What is the effect of low ratio of estrogen/progesterone ??
the contractions of the fallopian tubes and the uterus stops to allow the fertilized egg to implant in the uterus
* This occur during the luteal phase
Most fertilization occurs in ……..
the ampullary-isthmus junction of the ampulla
What is the ratio of estrogen/progesterone during pregnancy?
the ratio is low, and progesterone level remains high to calm the uterus
During delivery, cervical stretch causes …..
the hypothalamus to release more oxytocin, causing greater contractions and further expulsion of the fetus.
* After delivery, contractions continue to expel the placenta and shutting down open blood vessels in the uterus. After that, oxytocin level falls
hCG is synthesized in ……, secreted into …..
syncytiotrophoblast
fetal & maternal blood
* hCG in urine is the basis of home pregnancy test
hCG function is …….
maintaining the corpus luteum and its progesterone & estradiole secretion
* By the 10-12 week, the placenta takes over progesterone secretion, and hCG level decreases
The placenta can not produce estrogen because it lacks the enzyme ……, but it accomplishes that through the use of …..
17 α hydroxylase
DHEA-sulfate (from fetal and maternal adrenal)
* 17 α hydroxylase converts progestrone & pregnenolone to androstenodione & DHEA repsectively
Estriol is produced in …… from ….. . It’s function is ……
fetal liver & adrenal cortex, DHEA-sulfate
keeping the uterus supplied with blood
* It is a very weak estrogen, but it has very high level in the maternal blood
* DHEA-sulfate is desulfated in the placenta to produce estriol
* Low estriol levels may indicate a problem with the fetus. It is the best index for fetal health
The function of estradiol & estrone is ……..
keeping the uterus functioning during pregnancy
Prior to lactation, …… stimulate prolactin release from the pituitary
estrogen
* High estrogen & progesterone levels inhibit milk production
Ductal elongation in the breast is stimulated by …..
estrogen
No milk is produced in the breast during pregnancy because of ……
very high levels of estrogen and progesteron
- however, low levels are required for lactation
- Also required is low levels of T3, T4 & insulin for lactation to occur
What is the function of oxytocin in lactation?
Contraction of myoepithelial cells leading to milk let down
* Suckling stimulates oxytocin release from hypothalamus
The return to hormonal cyclicity after birth depends on what??
On nursing. As long as the nursing is taking place and prolactin is high, no cyclicity occur, because prolactin suppresses LH and FSH release
If the egg is not fertilized, corpus luteum regresses into ……
corpus albicans
