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Flashcards in Ovarian Cycle Deck (23):
1

What is Spinnbarkeit?

Stretchiness of cervical mucus

2

What is ferning?

In high oestrogen, just before ovulation, cervical mucus forms fern-like patterns due to crystallisation of NaCl on mucus fibres

Supports sperm penetration and increases ability to reach ovum

3

Which two hypothalamic nuclei project to the portal plexus of the pituitary gland?

1. Medial pre-optic nucleus
2. Arcuate nucleus

4

What controls GnRH secretion?

Feedback loops with gonadal hormones

5

What type of feedback loop is seen in the male?

Only negative feedback

6

What is the effect of testosterone on gonadotrophin output?

Depresses LH and FSH output

7

What is the effect of inhibin on gonadotrophin output

Selectively depresses FSH output

No effect on LH

8

What is the effect of slowly rising oestrogen in the female?

Negative feedback

Depresses LH and FSH output

9

What is the effect of rapidly rising oestrogen?

Positive feedback

Stimulates LH and FSH output

10

What is the effect of progesterone?

Depresses LH and FSH

1. Direct negative feedback
2. Inhibits positive feedback effect of oestrogen

11

What controls LH and FSH secretion?

1. Output of GnRH
2. Sensitivity of pituitary to GnRH
3. Both

12

Why is GnRH secretion pulsatile?

Continuous release would lead to adaptation and desensitisation

13

Where is the site of negative feedback by oestrogen and progesterone in the brain?

Arcuate nucleus

14

How does progesterone affect GnRH pulse?

Decreases pulse frequency

15

How does oestrogen affect GnRH pulse?

1. Decreases pulse amplitude (in negative feedback)
2. Induces GnRH surge (in positive feedback)

16

What causes the LH surge that triggers ovulation?

1. Gonadotropic cells of anterior pituitary hypersensitised due to inhibition of GnRH by negative feedback
2. Inhibition of anterior pituitary released due to rapidly rising oestrogen
3. GnRH surges due to hypothalamus stimulation by oestrogen
4. GnRH hyperstimulates hypersensitised anterior pituitary
5. Hypersecretion of LH

17

What hormonal changes initiate puberty?

GnRH pulses

18

What causes pubertal rise in GnRH?

Reaching body weight threshold

47kg for girls and 55kg for boys

19

How body weight sensed?

Leptin receptors in hypothalamus

Gives indication of fat stores and therefore whether puberty should start

20

What is menarche?

First period

21

How do hormones affect behaviour?

1. Directly via action on brain
2. Indirectly via non-neural action

22

What is the effect of testosterone on sexual behaviour in men?

1.Increases frequency of sexual thoughts
2. Increases frequency of sexual acts
3. Increases energy

23

What is the effect of oestrogen in females on male activity?

Increased systemic oestrogen in females increases male's sexual activity and acceptance of female's invitations