Page 674 - First Aid for the USMLE Step 1 2020, Thirtieth edition [MedicalBooksVN.com]_Neat

630 SectioN iii RepRoductive ` REPRODUCTIVE—PHySIOlOgy RepRoductive ` REPRODUCTIVE—PHySIOlOgy

Estrogen
SOURCE Ovary (17β-estradiol), placenta (estriol), adipose Potency: estradiol > estrone > estriol.
tissue (estrone via aromatization).

FUNCTION Development of genitalia and breast, female fat Pregnancy:
distribution. ƒ 50-fold  in estradiol and estrone
Growth of follicle, endometrial proliferation, ƒ 1000-fold  in estriol (indicator of fetal well-
 myometrial excitability. being)
Upregulation of estrogen, LH, and progesterone Estrogen receptors expressed in cytoplasm;
receptors; feedback inhibition of FSH and translocate to nucleus when bound by
LH, then LH surge; stimulation of prolactin estrogen.
secretion.
 transport proteins, SHBG;  HDL;  LDL.
LH Cholesterol

LHR
Theca cells Granulosa cells Cholesterol
cAMP Desmolase
Theca cell Androstenedione
Granulosa cell Androstenedione
Aromatase
Estrone
cAMP
Estradiol
FSHR
Follicle Estrogen
FSH

Progesterone

SOURCE Corpus luteum, placenta, adrenal cortex, testes. Fall in progesterone after delivery disinhibits
FUNCTION During luteal phase, prepares uterus for prolactin Ž lactation.  progesterone is
implantation of fertilized egg: indicative of ovulation.
ƒ Stimulation of endometrial glandular Progesterone is pro-gestation.
secretions and spiral artery development Prolactin is pro-lactation.
ƒ Production of thick cervical mucus
Ž inhibits sperm entry into uterus
ƒ Prevention of endometrial hyperplasia
ƒ  body temperature
ƒ  estrogen receptor expression
ƒ  gonadotropin (LH, FSH) secretion
During pregnancy:
ƒ Maintenance of pregnancy
ƒ  myometrial excitability Ž  contraction
frequency and intensity
ƒ  prolactin action on breasts

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