Lecture 4- Reproductive endocrinology Flashcards
… converts testosterone into dihydrotestosterone
5 alpha reductase
3 major classes of sex steroids, they differ with respect to the number of carbons they contain…
- pregnanes (21C)
- androgens (19C)
- estrogens (18C)
… converts testosterone to estradiol
aromatase
GnRH secretion from the hypothalamus is … due to the activity of pacemaker neurons that spontaneously produce action potentials resulting in secretory bursts of GnRH
pulsatile
… is more potent than DHEA and androstendione
testosterone
the 3 types of cells in the testis are
spermatic
leydig
sertoli
spermatic cells include mitotically active …. and meiotic …
spermatogenesis proceeds as the spermatic cells move through the wall of the seminiferous tubules from the… towards the…. and…
spermatogonia
spermatocytes
basal lamina
apical surface
lumen
… cells lie outside of the seminiferous tubules. They synthesize T in response to LH
Leydig
In the gonad, T regulates…
In the brain, T regulates… (after being aromatized to…)
Elsewhere in the body, T regulates
spermatogenesis
sexual behavior
(E2)
secondary sexual characteristics
… cells are the epithelial cells lining the seminiferous tubules. In response to FSH, they regulate spermatogenesis and produce the peptide hormone inhibin
Sertoli (sustentacular)
Inhibin has negative feedback actions on…
FSH secretion
Sertoli cells also produce an androgen binding protein that helps sequester T in the testis so spermatogenesis is…
continuous
Sertoli cells also secrete tubular fluid to provide…
nutrient support for spermatozoa
LH stimulates… synthesis by… cells
T
Leydig
FSH stimulates… cells to regulate… and synthesize …
sertoli
spermatogenesis
inhibin
3 other effects of T that are also important in females
regulate bone growth
stimulate muscle growth
stimulate erythropoesis
3 reproductive system effects of T
sexual differentiation
secondary sex characteristics
stimulate erythropoesis
DHT is non- … and more potent than…
aromatizable
Testosterone
… are used to treat breast and prostate cancers
aromatase inhibitors
…. used to treat hair loss
5 alpha reducatase (this is because DHT promotes hair loss in male pattern baldness)
4 important cells of ovary
oocytes
theca cells
granulosa cells
luteal cells
Each…. is enclosed in a follicle
oocyte
Are there oogonia after birth?
No. All oocytes are arrested in prophase of meiosis I
… cells are on the outside of the follicle
Theca (location and function is analogous to leydig cells)
… cells are the epithelial cells of the follicle. They produce fluid, regulate maturation and can start as a single layer and become several layers thick
granulosa (analogous to the sertoli cells)
…. cells are present after ovulation when the theca and granulosa cells are transformed into the corpus lutem
luteal
Theca cells synthesize …. in response to… which then diffuses into granulosa cells
androstenedione
LH
In response to …, granulosa cells convert androstenedione to…. which is converted to….
FSH
estrone
estradiol (E2)
5 effects of Estradiol (E2)
stimulates granulosa cell function and replication
regulates oocyte development
reg. female secondary sex charac.
regulator of bone turnover and arterial fxn
typically inhibits GnRH and LH secretion
In response to FSH, granulosa cells will also secrete…. which has a negative feedback effect on the anterior pituitary
inhibin
… surge stimulates ovulation
LH
Day 1-2 in the ovarian cycle is when there is a … rise and … development
gonadotropin
follicular
Day 3-5 in the ovarian cycle, there is an increase in… and… and there is …. selection
E2
inhibin
dominant follicle
Day 6-8 in the ovarian cycle, … decreases, there is an … peak, and an … surge (positive feedback action of E2 on GnRH and LH)
FSH
E2
LH
Day 9-11 in the ovarian cycle, … is completed, … and … formation
meiosis I
ovulvation
CL
Day 12-13, there is an increase in … and … and … are inhibited
E2
P
gonadotropins
Day 14-16 of the ovarian cycle, there is … regression, a decrease in …. and gonadotropins rise
CL
steroids
The menstrual or uterine cycle follows or parallels the … cycle
ovarian
menstrual phase begins when … regresses and the steroid support for uterine endometrium is lost
CL
differentiation of gonadal sex is determined by the presence of a gene on the Y chromosome that encodes for … protein
SRY
…. directs the indifferent gonad to become a testis
SRY
the fetal testis produces 2 hormones that regulate sexual differentiation of the internal genitalia–
Testosterone and
mullerian inhibiting substance (MIS)
in a develping male, T stimulates proliferation of the … duct system that will become the tubules associates with the male reproductive tract and MIS causes…
wolffian
mullerian duct system to regress
in a developing female, there is no significant production of gonadal steroids. Absence of …. causes regression of the …. duct system and absence of … results in proliferation or maintenance of the … duct system that becomes the tubules of the female reproductive tract
Testosterone
Wolffian
MIS
Mullerian
external genitalia: the early embryo and fetus are undifferentiated up to … weeks
9
…. is when there is an adrenal enzyme deficiency resulting in excess production of adrenal androgens
congenital adrenal hyperplasia
an example of CAH is when there is a mutation of … causing a female (XX genotype) to have a male phenotype
21 alpha hydroxylase
In … deficiency (also called guevodoces) they have an XY genotype but phenotype at birth is female
5 alpha reductase
in 5 alpha reductase deficiency, the phenotype at birth is female because development of the penis, scrotum, and prostate gland are … dependent
DHT
Do people who suffer from CAH have both male and female parts internally?
yes because of testosterone
in 5 alpha reductase deficiency, they will lack male genitalia but increased … secretion with onset of puberty completes differentiation
T
Testicular feminization or androgen insensitivity is a … genotype and … phenotype.
male
female
in pregnancy, the CL regresses after… months and … supports luteal steroidogenesis
3
hCG
… stimulates growth of myometrium
placental E2
… reduces uterine contractility and stimulates vasodilation
placental P
