Menstrual cycle

Question 1

Sequence of follicle formation

Answer 1

• primordial follicle
• primary follicle
• secondary follicle
• graafian follicle
• ovulation

Question 2

what are the stages of the menstrual cycle?

Answer 2

• follicular phase
• ovulation
• luteal phase

Question 3

The follicular phase

Answer 3

• This phase begins on the first day of bleeding.
• LH levels rise steadily
• FSH levels also rise
• LH and FHS stimulate follicle growth
• low oestrogen
• as follicle grows it secretes oestrogen
• LH surge which triggers ovulation

Question 4

draw the menstual cycle diagram

Answer 4

4 hormones

Question 5

Follicular phase pre ovulation

a) which hormone is secreted from the hypothalamus? and its action
b) which hormones are secreted from the anterior pituitary and what are their action?
c) as the follicle is developing what does it secrete and what does this do?

Answer 5

a) GnRH, positive feedback to the A.pit and causes FSH and LH to be secreted.
b) LH and FSH, cause the follicle to develop
c) inhibin, and v. low oestrogen, these have negative feedback on the A.pit and low oestrogen on the hypothalamus.

Question 6

The late follicular phase

a) as the follicle develops into a mature follicle and produces more oestrogen what does this cause?
b) what is positive feedback?
c) what does oestrogen do?
d) what does the LH surge trigger?

Answer 6

a) positive feedback from the high oestrogen levels causes a LH surge
b) when a signal causes something to move further and further away from the normal
c) causes the endometrium to thicken
d) ovulation

Question 7

Luteal phase

What does the hypothalamus secrete? and what does the A.pit secrete?

Answer 7

Hypo=GnRH

A.pit=LH and FSH

Question 8

What does the corpus lute produce?

Answer 8

moderate oestrogen wich positive feedback to the hypo and A.pit
high progesterone levels which negative feedback to the hypo and A.pit… negative feed back dominates

Question 9

What does the progesterone produced by the CL do?

Answer 9

Keeps the LH and FSH down

Question 10

what happens if there is no pregnancy?

Answer 10

• CL degenerates and stops producing progesterone
• FSH and LH are no longer inhibited and so a new cycle starts
• menstruation occurs

Question 11

What happened if fertilisation occurs?

Answer 11

• CL maintained by the hCG produced by the chorion … becomes the CL of pregnancy
• hCG maintains the utrine lining until the placenta takes over as main producer of progesterone at 3 months

Question 12

what does the placenta take over maintaining the lining of the uterus by producing progesterone?

Answer 12

3 months