Reproductive Physiology Flashcards
What is the pleasure and reward pathway?
Mesolimbic dopaminergic pathway
Describe the mechanism of increased blood flow during penile erection
Increased nitric oxide synthase (NOS) activity → increased NO → increased cGMP production → dilation of arterial smooth muscle → increased blood flow also compresses venous outflow of blood → leads to increase in size of penis
What is the mechanism of viagra?
viagra inhibits phosphodiesterase so it no longer deactivates cGMP –> potentiating its vasdilatory effects
Role of seminiferous tubules
produce sperm
Role of Leydig cells
secrete testosterone in response to LH –> sexual differentiation and spermatogenesis
Role of Sertoli cells
support spermatogenesis in response to FSH by regulating the environment of the seminiferous tubule
Role of epididymis
Sperm are released from the testis and stored here prior to ejaculation
What is the pathway of sperm during ejaculation?
At ejaculation, sperm are released into the contractile Vas Deferens then pass through the
urethra.
During ejaculation sperm are mixed with fluid from the seminal vesicles and the prostate
gland.
role of ovaries
produce mature oocytes monthly + progesterone and eostrogens
role of thecal cells
cells of developing follicles that produce androgens in response to LH
role of granulosa cells
respond to FSH and produce eostrogens by aromatising androgens
describe the HPO axis
Hypothalamic-pituitary-ovarian (HPO) axis
Hypothalamus secretes GnRH which stimulates pituitary gland
Pituitary gland release LH and FSH which stimulate theca and granulosa cells in ovaries
Theca and granulosa cells secrete steroid hormones oestrogen and progesterone which inhibit pituitary secretion (except at ovulation)
what are the 3 phases of the ovarian cycle?
Follicular phase
Ovulation
Luteal phase
What occurs during the follicular phase?
Development and growth of several follicles (although only one is selected to ovulate)
Stimulated by FSH
Leads to increased production of oestrogen which inhibits FSH and LH secretion
What occurs during ovulation?
Follicle continue to grow, producing more oestrogen.
Dominant follicle is selected for ovulation
Oestrogen begins to stimulate secretion of LH and FSH of pituitary leading to LH surge in ovulation
what occurs during the luteal phase?
After ovulation, follicle develops into corpus luteum
Corpus luteum produces progesterone (and some oestrogen)
What are the 3 phases of the endometrial cycle?
menstruation
proliferative phase
secretory phase
what happens to the endometrium during menstruation?
Day 1-5 of cycle
Shedding of blood and endometrial lining of uterus
Remaining basal endometrium very thin
What occurs during the proliferative phase of the endometrial cycle?
Day 5-14 of cycle estrogen peaks - Stimulation of endometrial cell proliferation, increase in thickness, increase in number and length of glands, increased in length of arteries
What occurs during the secretory phase of the endometrial cycle?
If there is no pregnancy, progesterone falls and endometrium sheds →
If there is a pregnancy, corpus luteum will continue to maintain progesterone levels → no menses
in what meiotic phase is the oocyte afterovulation
arrested in metaphase 2 (2n)
describe the acrosome reaction
acrosome is a package of enzymes from the sperm that digests the zona pallucida of the follicle so the head of the sperm can enter and fertilise the egg
what causes the resumption of meiosis during fertilization?
calcium influx
How are the 1st and 2nd polar bodies formed?
1st - during ovulation when meiosis 1 completes (2x daughter cells with 2n)
2nd - during fertilisation when maternal meiosis 2 is completed (2x daughter “cells” with 1n)
= 2 polar bodies + 1x haploid maternal pronucleus + 1x haploid paternal pronucleus
