6.0 The Ovarian Cycle

Question 1

How long is the ovarian cycle?

Answer 1

24-32 days

Question 2

What is the name of the period of the ovarian cycle before ovulation? How long is it?

Answer 2

Follicular stage (10-14 days)

Question 3

What is the name of the period of the ovarian cycle after ovulation? How long is it?

Answer 3

Luteal phase (12-15 days)

Question 4

What hormone dominates pre-ovulation?

Answer 4

oestrogen

Question 5

What hormone dominates post-ovulation?

Answer 5

Progesterone

Question 6

What is the fate of preantral follices?

Answer 6

Majority undergo <b>atresia</b><br></br>Some spontaneously form antral follicles<br></br><br></br><b>No antral follicles can form in luteal phase due to effect of progesterone</b>

Question 7

What are the effects of oestrogen in follicular stage?

Answer 7

1) ↑ LH → follicular growth and maturation to pre-ovulatory follicle<br></br><br></br>2) Arterial growth<br></br><br></br>3) <b>Thickening of endometrium</b> towards ovulation<br></br><br></br>4) ↑ mucus secretion

Question 8

During what phase does the endometrium develop progesterone receptors?

Answer 8

Follicular phase (even though no progesterone in this phase)

Question 9

What occurs in luteal phase?

Answer 9

1) Arteries taken on spiral form<br></br><br></br>2) ↑ Progesterone → ↓ mucus secretion and prevents sperm penetration

Question 10

What is the property of mucus in follicular and luteal phase?

Answer 10

Follicular = <b>Spinnbarkeit</b> (towards ovulation)<br></br><br></br>Luteal = <b>Ferning</b> (uniform, organised structure)

Question 11

What are the endocrine cells of the pituitary gland?

Answer 11

<b>1) Gonadotrophs</b> → LH + FSH<br></br><b>2) Somatotrophs</b> → GH<br></br><b>3) Lactotrophs</b> → Prolactin<br></br><b>4) Thryotrophs</b> → TSH<br></br><b>5) Corticotrophs</b> → ACTH

Question 12

What nuclei are involved with GnRH release?

Answer 12

1) Medial pre-optic nucleus<br></br>2) Arcuate nucleus

Question 13

What feedback loops exist in males?

Answer 13

<b>Only negative feedback</b><br></br><br></br>Androgens → ↓ FSH + LH secretion by negatively inhibiting Hypothalamus and ant. pituitary<br></br><br></br>Inhibin → ↓ FSH secretion by negatively inhibiting the ant. pituitary ONLY

Question 14

“What is the ““pelvic clock”””

Answer 14

A term used to describe the relationship of follicular dynamics and the timing of the menstrual cycle

Question 15

What alterations are seen in LH secretion around puberty?

Answer 15

<b>Pre-puberty</b><br></br>- Low LH secretion<br></br><br></br><b>Early-mid puberty</b><br></br>- Nocturnal augmentation of LH secretion<br></br><br></br><b>Adulthood</b><br></br>- Establishment of high basal levels of LH secretion with no diurnal rhythm

Question 16

What precedes LH, FSH and sex steroid increases in puberty?

Answer 16

<b>GnRH pulses</b><br></br><br></br>Exogenous GnRH pulses → initiate puberty

Question 17

What weight does puberty occur at for girls and boys?

Answer 17

47kg for girls<br></br><br></br>55kg for boys<br></br><br></br>This may be due to <b>leptin</b>