Topic 7: Reproductive System

Question 1

Hypothalamic-pituitary-ovary control of female reproductive function is a a)____________ mechanism.
The hypothalamus releases b)________ which works on the pituitary gland that goes on to release c)________ and d)________ which work on the ovary

The ovary then releases e+f)____________

• LH
• Oestrogen
• FSH
• Negative
• GnRH
• Progesterone

Answer 1

a) Negative
b) GnRH
c) LH
d) FSH
e + f) Progesterone / Oestrogen

Question 2

What are the primary mechanisms of the combined contraceptive pill? what is its failure rate

Answer 2

• Inhibits FSH and LH release preventing: follicular development, egg maturation, ovulation

Failure rate = 2-8% irl

Question 3

For the implanted conceptus to survive, it must send a signal to the mother to maintain progesterone support and function of the corpus luteum (CL).
What is secreted by the trophoblast that does this

Answer 3

Chorionic gonadotrophin (hCG).

Question 4

How long is normal gestation in humans

Answer 4

37-42 weeks

Question 5

During labour what hormone does oestrogen stimulate the release of that causes uterine contractions and cervix dilation?

Answer 5

Prostaglandin E2 (cervix dilation) and PGF2-alpha (uterine contractions)

Question 6

• a)________ involved in maturation of the foetal HPA axis
• Foetal adrenal gland matures so expresses b)_______ enzyme to permit synthesis of substrates for c)__________ synthesis
• Placental trophoblast expresses d)__________ permitting secretion of oestradiol
• e)___________ makes myometrium sensitive (stimulates expression of prostaglandin E and F receptors)
• e)___________ stimulates prostaglandin PGE2 and PGF2alpha secretion
• Oestradiol
• 17alpha-hydroxylase
• Placental CRH
• Oestrogen
• Aromatase

Answer 6

a) Placental CRH
b) 17alpha-hydroxylase
c) Oestrogen
d) Aromatase
e) Oestradiol

Question 7

What are:

a) Germ Cells
b) Somatic cells that nurse germ cells
c) Other somatic cells in the gonads

For MALES and FEMALEs respectively

• Spermatozoa
• Leydig Cells
• Granulosa Cells
• Oocytes
• Sertoli cells
• Thecal Cells

Answer 7

MALES:
a) Spermatozoa
b) Sertoli cells
c) Leydig cells

FEMALES:
a) Oocytes
b) Granulosa cells
c) Thecal cells

Question 8

In females, how many haploid germ cells are produced by each meiotic division?

And how many in males?

Answer 8

females = 1
males = 4

Question 9

A female in oestrus could be detected by which of the following?

a) Visual
b) Pheromonal
c) Behavioural
d) Presence of a corpus luteum in ovary
e) Presence of high levels of oestrogen in the blood

Answer 9

A, B, C, E

Question 10

How do menstrual cycle differ from oestrus cycles?

Answer 10

Females are sexually receptive throughout the cycle not just at ovulation

Question 11

Long day patterns of melatonin secretion will inhibit what hormone secretion in short day breeders (but not in long day breeders)?

Answer 11

GnRH

Question 12

What hormones are released from the follicles and what is released from the corpus luteum in the HPO axis

Answer 12

Follicles: Oestrogen, Inhibin
CL: Progesterone

Question 13

What are two clues females give when they are ovulating

Answer 13

• Behavioural cues
• Pheromonal

Question 14

What are the 4 phases of oestrus and what happens during them?

Answer 14

1) Proestrus: Follicular phase
- follicles grow
- dominant follicles secreted
- oestrogen levels rise

2) Oestrus: Mating behaviour
- dominant follicle ovulates

3) Metoestrus: Early luteal
- oestrus ends
- CL forms

4) Dioestrus: Mid/late luteal
- CL size maximal
- progesterone output maximal

If no pregnancy, CL regresses

Question 15

Oestrogen has different effects on the HPO axis depending on its quantity. How do the different quantities influence the axis and follicle growth

Answer 15

• Low Oestrogen: No negative feedback = no reduction in FSH hence good stim of follicle growth
• When follicle large enough, oestrogen released causing reduction in FSH
• High Oestrogen: causes LH surge