Reproduction Flashcards
Functions of testes
Make sperm and Testosterone
Accessory duct function
Storage, maturation, and transport of sperm
Seminal Fluid
Seminal vesicles produce the majority of the fluid
Path of sperm
Seminiferous tubules to rete testis to efferent ducts to epididymis
Leydig Cells
Make Testosterone, outside the seminiferous tubules
Sertoli Cells function
Are support cells
- Transfer nutrients to developing germ cells
- Form tight junctions that form blood-testis barrier
- Secrete fluid into seminiferous tubules to move sperm towards epididymis
- Make ABP to concentrate T in Sem Tubules
- Make Aromatase to convert T to estradiol
How is testosterone maintained in in seminiferous tubule lumen?
Leydig cells have LH receptors (adenyl cyclase pathway to PKA to nuc) to initiate T production. T diffuses out to bloodstream to carrier proteins and Sertoli Cells.
Seroli Cells have FSH receptors (adenyl cyclase path) to make Antigen Binding protein, inhibins, and aromatase to effect Leydig cells. T binds to ABP which moves it to Lumen to maintain high lvls of T in seminiferous tubules.
Targets of Testosterone
Causes growth of testes and muscle
DHT
Dihydrotestosterone made from plasma testosterone via 5 alpha Reductase and causes growth of prostate, scrotum, penis, and bone
Functions of ovary
- Produce and release mature oocytes
2. Synthesize and release steroid hormones
Pre fertilization growth of egg
Primordial follicles generated during fetal development and divide to primary follicles as a neonate.
As FSH and LH induces the Ovarian Cycle progress continues until the oocyte arrests at prophase 1 at ovulation.
Corpus Luteum
Consists of theca and Granulosa cells
FSH/LH and females
Theca cells only have LH receptors so they produce progesterone.
Granulosa cells have LH receptors during its luteal phase to also produce progesterone, otherwise it only has FSH which produces estrogen
Follicular phase
In the follicular phase of the menstrual cycle, FSH and LH stimulate synthesis and secretion of estradiol by follicular cells. One of the actions of estradiol is negative feedback on the anterior pituitary cells to inhibit further secretion of FSH and LH. Thus, the follicular phase is dominated by negative feedback effects of estradiol.
Midcycle
Pattern changes. Estradiol levels rise sharply due to increased proliferation of follicular cells. It surpasses a limit leading to positive feedback of estradiol on ant pit via upreg of GnRH receptors. This causes the ovulation surge of FSH and LH. (LH higher than FSH as FSH is still affected by Inhibin)
Luteal Phase
major hormone secreted is progesterone. It has neg feedback on ant pit.
Inhibin
Produced by ovarian granulosa cells and inhibits FSH secretion from ant pit
Activin
Produced by ovarian granulosa cells and stims FSH secretion
Ovarian and Uterine cycle Drawing
On Paper
Role of FSH in cycles
Via granulosa cell receptors, initial actions are stimulation of granulosa cells and therefore estradiol synth. Estrogen promotes vasculization of uterine wall.
Therefore, follicular phase is dominated by FSH, LH low, and estrogen is gradually rising.
Luteal phase and the cycles
During the luteal phase, progesterone neg feedback on FSH. LH freq reduced but more of it. LH maintains the corpus luteum. On day 24 to 26, corpus luteum fades and progesterone and estradiol levels plunge causing loss of support of uterine lining.
Reproductive hormones and age
At puberty, GnRH and LH/FSH becomes pulsatile and highest at night. LH higher than FSH.
Menopause - follicles are depleted from ovaries and estrogen and progesterone stops therefore LH and FSH have no neg feedback. Higher FSH than LH.
Corticol reaction
When Zona Pelucida forms a barrier to polyspermy once implanted.
Capacitation
When protein coat of sperm is washed after several hours in female reproductive tract allowing fertilization to occur.
Acrosomal reaction
When sperm encounters the Zona Pelucida and releases its contents
Timing of implantation
Occurs in the uterus 5-9 days after fert (4 days to uterine cavity, 1 day floating) and corresponds to when uterus is ready (day 21, 5-9 days post ovulation) and at peak progesterone, estrogen, and inhibin.
Process of implantation
Zone pellucida dissolves (hatching)
blastocyst lines up with endometrium (apposition)
Integrins make connections (adhesion)
Trophoblast secretes enzymes to endometrium (invasion)
Pregnancy Test hormone and function
based on HCG, which stims LH receptors on C Luteum to sustain it and keep it producing progesterone and estrogen. Produced by syncytiotrophoblast.
HCS/hPL
similar to GH and allows higher glucose in mother therefore able to provide for fetus
Hormones and gestation weeks
Until week 9, corpus luteum produces progesterone and estrogen.
Post week 9, Placenta produces HCG, prog, estrogen, and HCS. Also coincides with mother producing Prolactin from pit.
Progesterone:Estrogen ratio
Higher prog promotes gestation and inhibits delivery, once gestation is complete, estrogen rises to promote contractions
Lactation
Two components: synthesis and release
Milk Secretion/Synth
Continuous process and regulated by prolactin. Synthesized in alveolar cells to alveolar lumen as storage
Milk Ejection
Intermittent process
Regulated by oxytocin and mechanoreceptors to suckling releases SON and PVN from hypo to release oxytocin from pit (dopamine inhib). Contracts the myoepithelial cells.
Why is fertility reduced in breastfeeding women?
GnRH producing neurons are inhibited by suckling which stops reproductive cycle. Via actions of prolactin
