Reproductive Physiology

Question 1

What is the pleasure and reward pathway?

Answer 1

Mesolimbic dopaminergic pathway

Question 2

Describe the mechanism of increased blood flow during penile erection

Answer 2

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

Question 3

What is the mechanism of viagra?

Answer 3

viagra inhibits phosphodiesterase so it no longer deactivates cGMP –> potentiating its vasdilatory effects

Question 4

Role of seminiferous tubules

Answer 4

produce sperm

Question 5

Role of Leydig cells

Answer 5

secrete testosterone in response to LH –> sexual differentiation and spermatogenesis

Question 6

Role of Sertoli cells

Answer 6

support spermatogenesis in response to FSH by regulating the environment of the seminiferous tubule

Question 7

Role of epididymis

Answer 7

Sperm are released from the testis and stored here prior to ejaculation

Question 8

What is the pathway of sperm during ejaculation?

Answer 8

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.

Question 9

role of ovaries

Answer 9

produce mature oocytes monthly + progesterone and eostrogens

Question 10

role of thecal cells

Answer 10

cells of developing follicles that produce androgens in response to LH

Question 11

role of granulosa cells

Answer 11

respond to FSH and produce eostrogens by aromatising androgens

Question 12

describe the HPO axis

Answer 12

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)

Question 13

what are the 3 phases of the ovarian cycle?

Answer 13

Follicular phase
Ovulation
Luteal phase

Question 14

What occurs during the follicular phase?

Answer 14

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

Question 15

What occurs during ovulation?

Answer 15

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

Question 16

what occurs during the luteal phase?

Answer 16

After ovulation, follicle develops into corpus luteum

Corpus luteum produces progesterone (and some oestrogen)

Question 17

What are the 3 phases of the endometrial cycle?

Answer 17

menstruation
proliferative phase
secretory phase

Question 18

what happens to the endometrium during menstruation?

Answer 18

Day 1-5 of cycle
Shedding of blood and endometrial lining of uterus
Remaining basal endometrium very thin

Question 19

What occurs during the proliferative phase of the endometrial cycle?

Answer 19

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

Question 20

What occurs during the secretory phase of the endometrial cycle?

Answer 20

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

Question 21

in what meiotic phase is the oocyte afterovulation

Answer 21

arrested in metaphase 2 (2n)

Question 22

describe the acrosome reaction

Answer 22

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

Question 23

what causes the resumption of meiosis during fertilization?

Answer 23

calcium influx

Question 24

How are the 1st and 2nd polar bodies formed?

Answer 24

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