L34 - Reproduction 1

Question 1

What are male reproductive functions?

Answer 1

spermatogenesis, hormone secretion, delivery of sperm to the female, fall asleep

Question 2

What are female reproductive functions?

Answer 2

oogenesis, hormone secretion, reception of sperm, fertilization, gestation, parturition, lactation

Question 3

When does spermatogenesis begin?

Answer 3

puberty

Question 4

When does oogenesis begin?

Answer 4

fetal life

Question 5

What are the characteristics of gametogenesis in males?

Answer 5

quiescent till puberty (mitosis stage)

4 sperm per germ cell

Question 6

What are the characteristics of gametogenesis in females?

Answer 6

development in embryo (start of meiosis)
born with all her 1˚ oocytes
1 egg per germ cell

Question 7

What are the hormones released by the anterior pituitary gland?

Answer 7

ACTH (adrenocorticotropin)
FSH, LH (reproduction)
TSH (thyroid)
GH (growth hormone)

Question 8

What are the hormones released by the posterior pituitary gland?

Answer 8

vasopressin (ADH) and oxytocin

Question 9

What is GnRH?

Answer 9

tropic hormone which releases gonadotropins

GnRH = gonadotropin-releasing hormone

Question 10

What is LH?

Answer 10

luteinizing hormone

Question 11

What is FSH?

Answer 11

follicle-stimulating hormone

Question 12

What are the major hormones in males and females?

Answer 12

androgens (includes testosterone) are dominant in males
oestrogens are dominant in females
progesterone in females; ‘pro-gestation’
inhibin; negative feedback!

Question 13

Which cells carry out spermatogenesis?

Answer 13

sertoli cells support and regulate spermatogenesis + supply androgen binding protein
leydig cells supply testosterone

Question 14

How is spermatogenesis regulated?

Answer 14

GnRH stimulates the release of FSH and LH from the anterior pituitary gland -> LH stimulates leydig cells to release testosterone while FSH stimulates sertoli cells to release cell products which support sperm development

Question 15

What is the role of testosterone?

Answer 15

aids in sperm development and is sent out into the rest of the body to elicit a variety of effects

Question 16

How is testosterone sequestered in different parts of the body?

Answer 16

sertoli cells release androgen-binding protein (ABP) which binds to testosterone and sequesters it inside the testes
in the blood, testosterone binds to serum albumin and sex hormone-binding globulin (SHBG)

Question 17

If you wished to reduce sperm production without inhibiting testosterone levels, you could block production of:

Answer 17

FSH

Question 18

Is testosterone secretion continuous from puberty?

Answer 18

yes, provides negative feedback to LH and GnRH

Question 19

Which hormones are involved in negative feedback?

Answer 19

inhibin and testosterone

Question 20

If a man were to take testosterone supplements…

Answer 20

LH levels would decrease

endogenous testosterone production would decrease

Question 21

What happens during the ovarian cycle?

Answer 21

a single follicle is selected for maturation -> as it matures, theca and granulosa cells regulate hormonal balance -> ovulation occurs and egg leaves ruptured follicle -> follicle is converted into a corpus luteum

Question 22

Where do the primary hormones come from?

Answer 22

GnRH from the hypothalamus
FSH and LH from the anterior pituitary
oestrogen, progesterone and inhibin from ovary

Question 23

How is the early to mid follicular phase hormonally controlled?

Answer 23

FSH stimulates a follicle to start developing
LH stimulates theca cells to release androgens -> androgens are converted into estrogens by granulosa cells -> estrogens have a local + feedback loop on the granulosa cells to ramp up estrogen production and a - feedback loop on FSH, LH and GnRH which ensures that other follicles aren’t selected

Question 24

What is the role of Anti-Müllerian hormone?

Answer 24

reduces sensitivity of other follicles to FSH, allowing a single dominant follicle to emerge

Question 25

How is the late follicular and ovulation phase hormonally controlled?

Answer 25

when estrogen reaches a certain level, system switches from - feedback to + feedback resulting in surges in LH and FSH -> LH surge is directly responsible for stimulating ovulation
FSH does not increase as much due to secretion of inhibin

Question 26

How is the early to mid luteal phase hormonally controlled?

Answer 26

corpus luteum releases progesterone, estrogen and inhibin
high progesterone maintains the endometrium
inhibin decreases follicles
there is also a decrease in GnRH, LH and FSH

Question 27

How is the late luteal phase hormonally controlled (when no pregnancy)?

Answer 27

CL spontaneously dies, low hormones, menses, higher FSH and LH -> new follicle

Question 28

If follicles lost their sensitivity to gonadotropins…

Answer 28

GnRH/FSH/LH levels would increase and estrogen levels would decrease