15

Question 1

what are the two commonalities found between the sexes?

Answer 1

1. formation of gametes
2. hypothalamic/pituitary control of reproduction

Question 2

define gametogenesis

Answer 2

gametes with 23 chromosomes are produced from cells in the gonads with 46 chromosomes

Question 3

compare and contrast meiosis

Answer 3

meiosis:
- DNA replicated one
- cells undergo division twice

mitosis:
- DNA replicated once
- cells undergo division once

Question 4

two ways in which meiosis promotes genetic variation

Answer 4

crossing over and independent assortment

Question 5

draw the flow chart for hypothalamic/pituitary control of reproduction

Question 6

describe the secretion of GnRH

Answer 6

GnRH is secreted in pulses from neuroendocrine cells in the hypothalamus. This pulsatility is critical for reproductive function

Question 7

how is the secretion of GnRH regulated?

Answer 7

by hormonal feedback and higher brain centres

Question 8

pulse frequency/amplitude of GnRH release changes during

Answer 8

development

Question 9

low frequency of GnRH =>

Answer 9

FSH release

Question 10

high frequency of GnRH =>

Answer 10

LH release

Question 11

label a diagram of the common XY male reproductive system

Question 12

define the testis

Answer 12

primary reproductive organ - what develops the gametes

Question 13

why is the location of the testes important?

Answer 13

sperm production is optimal at 2-3’C lower than body temperature (37’C)

Question 14

describe the rate of sperm production

Answer 14

• takes 64 days
• 200 million/day

Question 15

label a diagram of the testes

Question 16

sperm are made in the — —- and then further mature in the ——

Answer 16

seminiferous tubule; epididymis

Question 17

what is the role of Sertoli cells?

Answer 17

support sperm development

Question 18

what is another name of Sertoli cells?

Answer 18

sustentacular cells

Question 19

what is the role of Leydig cells?

Answer 19

secrete testosterone

Question 20

what is another name of Leydig cells?

Answer 20

insterstitial cells

Question 21

label a diagram of the testes

Question 22

what is the function of tight junctions between Sertoli cells?

Answer 22

responsible for the blood-testis barrier; this is important as the sperm must be separate from immune system cells as they could otherwise be attacked as they look ‘foreign’

Question 23

describe spermatogenesis

Answer 23

1. spermatogonia (2n) are formed during fatal development by mitosis and differentiation. following each round of mitosis, one spermatogonium stays to produce more
2. the other cell begins to undergo meiosis forming spermatocytes
3. four spermatids are produced from one starting spermatocyte: primary spermatocytes (2nx2) – meiosis I -> secondary spermatocytes (n x 2) – meiosis II -> spermatids (n)
4. spermiogenesis: spermatids mature into spermatozoa, meaning they lose their cytoplasm and gain a tail
5. the spermatozoa are pinched out into lumen of seminiferous tubules

Question 24

describe the acrosome

Answer 24

• derived from the Golgi apparatus
• contains hyaluronidase and acrosin which breakdown the zona pellucid, a glycoprotein coat that covers the oocyte

Question 25

what is in semen?

Answer 25

spermatozoa (1%) + secretions of accessory glands: water, lubricant (mucous), buffers (neutralise acid), nutrients (fructose, citric acid, vitamin C, carnitine), enzymes, zinc, prostaglandins

Question 26

function of prostaglandins

Answer 26

can both induce and inhibit smooth muscle contraction for timing of ejaculation

Question 27

what three EXOCRINE glands do spermatozoa go through to form semen?

Answer 27

seminal vesicles, prostate gland, bulbourethral gland

Question 28

label a flow chart of hormonal control of gametogenesis in males

Question 29

role of FSH in males

Answer 29

stimulates Sertoli cells which then: - support sperm development - secrete inhibin - secrete androgen binding protein

Question 30

function of inhibin

Answer 30

a hormone that inhibits FSH release

Question 31

function of androgen-binding protein

Answer 31

helps to concentrate androgens in testis

Question 32

role of LH in males

Answer 32

stimulates Leydig cells which then: - secrete testosterone in response to LH

Question 33

draw a diagram for testosterone secretion throughout life

Question 34

describe anatomical changes in common XY throughout life

Answer 34

first trimester: sex differentiation second and third trimester: penis growth and testis descent childhood -> puberty: testicular volume changes from being mostly Sertoli cells to mostly Germ cells

Question 35

hypogonadism in XY

Answer 35

- decreased functional activity of the testes - decreased production of androgens, inhibin B, AMH and/or impaired sperm production

Question 36

primary hypogonadism

Answer 36

- primary defect is in the gonad (testes) - due to genetic variations, injuries, inflammation, infections - decreased testosterone secretion causes there to be no negative feedback to the anterior pituitary and hypothalamus always secrete GnRH, LH, FSH to compensate - solution: give exogenous T to the individual

Question 37

secondary hypogonadism

Answer 37

- primary defect is in the hypothalamus or anterior pituitary - this causes decreased GnRH, LH, FSH leading to decreased testosterone - solution: substitute hormone deficiency

Question 38

why is exogenous T not always the best solution for hypogonadism?

Answer 38

this could continue decreasing LH and FSH, affecting sperm production/fertility

Question 39

INSL3

Answer 39

insulin-like factor 3 produced by Leydig cells and involved in normal testicular descent

Question 40

AMH

Answer 40

anti-Mullarian hormone - prevents the formation of female reproductive structures in male embryos

Question 41

inhibit B

Answer 41

inhibits FSH

Question 42

testosterone - sex-specific tissues

Answer 42

- Promotes spermatogenesis - Maintains and stimulates secretion from prostate and seminal vesicles - Maintains reproductive tract

Question 43

testosterone - other reproductive effects

Answer 43

- Increases sex drive - Negative feedback effects on GnRH, LH (and FSH) secretion

Question 44

testosterone - secondary sex characteristics

Answer 44

- Male pattern of hair growth (including baldness) - Promotes muscle growth - Increases sebaceous gland secretion

Question 45

testosterone - non-reproductive effects

Answer 45

- Promotes protein synthesis - Increases aggression - Stimulates erythropoiesis

Question 46

how can we reduce male pattern baldness and benign prostate enlargement?

Answer 46

inhibitors of 5alpha-reductase