Hormones of Reproductive System Flashcards
XX
Female
XY
Male
Until 8th week of gestation
M/F = homologous = one pair of gonads (primary sex organs) and 2 pairs of ducts (Wolffian and Müllerian ducts)
Default sex
Females - requires no hormones or ovaries to develop
Brain development
Low levels of estrogen
Y chromosome contains a gene
Necessary to produce a protein TDF (testes determining factor) that directs fetal gonads to differentiate
Y chromosome produces MIS
Müllerian inhibiting substance or regression hormone - causes female structures that are precursor for fallopian tubes, uterus, and cervix to shrivel
Formation of internal sex organs (men)
Testes → testosterone → Wolffian ducts develop into the seminal vesicles, vas deferens, prostate
Testes → MIS → Atrophy of Müllerian ducts
Formation of internal sex organs (females)
Ovaries → no testosterone → Wolffian ducts atrophy
Ovaries → no MIF → Müllerian ducts develop into the uterus, vagina, fallopian tubes
External sex organs (male)
Testosterone → penis, urethra, scrotum
External sex organs (female)
No testosterone → clitoris and external labia
Direct gene activation
-Lipid soluble, steroid hormones
-Diffuse through cell membranes
-Bind to intracellular receptor
-Activated hormone receptor/complex binds with gene, turning it on
-Gene transcribes mRNA
-Ribosomes use mRNA to synthesize enzymes to stimulate cell activity or synthesize structural proteins to be excreted or used within the cell
Second messenger systems
-Amino acid and protein based
-Cannot pass through cell membranes
-Bind to cell membrane receptors
-Activate G proteins in membrane to produce cyclic AMP in cytoplasm
-Cyclic AMP acts as second messenger inside cell activating protein kinases
-Protein kinases trigger cellular responses
GnRH
Gonadotropin-releasing hormone
GnRH source
Hypothalamus
