Menstrual Cycle

Question 1

What changes to make us hit puberty?

Answer 1

(Starting point not understood) BUT…

Thought to be the withdrawl of central inhibition of GnRH release

GnRH secreted for the hypothalamus

Increase in FSH, LF & sex steroids

Increased GH

Question 2

What factors can influence when we hit puberty?

Answer 2

Weight

Nurtrition

Lepsin

Insulin

Genetic Factors

Exercise

Social-culture

Question 3

What does Inhibin do?

Answer 3

Inhibits the release of FSH and to a lesser extend LH

Question 4

What are the effects of Relaxin?

Answer 4

Inhibits the contraction of the uterus smooth muscle

During labour it increases the flexability of the pubic symphysis & dilates the uterine cavity

Question 5

Describe the menstrual cycle from day 1-5 (menstrual flow and ovaries)

Answer 5

Menstrual flow

• Decreased progesterone + oestrogens

= Release of prostaglandins

= Constriction of arterioles

= Cells deprived of O2 and die

Ovaries

FSH causes primordial follicles to develop into primary follicles and then into 2ndary follicles (takes a few months)

Question 6

Describe the menstrual cycle from day 6-13

Answer 6

Oestrogens into blood from follicles - stimulate the endometrium repair & proliferative phase

Pre-ovulation phase

• 2ndary follicles in the ovaries secrete oestrogens + inhibin.

Dominant follicle - Graafian follicle - decreased FSH

Question 7

Describe what happens on day 14

Answer 7

• Uterus endometrium still proliferating – dependent upon implantation if to be maintained
  •Ovulation
  •High levels oestrogen (feedback to) hypothalamus which secretes GnRH = LH surge
  •Rupture of graafian follicle results in expulsion 2ndary oocyte into fallopian tube

Question 8

During the luteal phase give:

a) The 2 cells whcih secrete oestrogens
b) The 4 hormones that the corpus luteum secretes
c) the duration of the phase

Answer 8

a) Theca cells and Granulosa cells secrete oestrogens
b) Corpus luteum secretes:
- Oestrogen
- Progesterone
- Relaxin
- Inhibin
c) 14 days (always)

Question 9

What is human chorionic gonadotrophin (HCG)

Answer 9

Stimulates oestrogen and progesterone production

Produced by the ovaries.

Diminishes once the placenta is large enough to produce oestrogen and progesterone.

Pregnancy test hormone

Question 10

What does estrogen do in pregnancy?

Answer 10

Promotes pregnancy

Prepares the breast for lactation & uterus for a baby

Regulates the levels of progesterone

Question 11

What is the role of progesterone during pregnancy?

Answer 11

Keeps the pregnancy going

Stops the uterus contracting too easily

Builds up the the endometrium - prevents mischarge

Question 12

What is the role of prolactin in pregnancy?

Answer 12

From the anterior pituitary

Increases cells that produce milk and stimulates milk production (provents estrogen and progesterone)

Question 13

Describe the role of relaxin in pregnancy?

Answer 13

High in early pregnancy

Limits uterine activity, softens the cervix – cervical ripening in preparation for delivery

Question 14

Describe the role of oxytocin in pregnancy?

Answer 14

Triggers “caring” reproductive behaviour.

• Responsible for uterine contractions during pregnancy and labour.
• Cause of contractions felt during breast feeding.
• Drug used to induce labour

Question 15

Describe the role of prostaglandins in pregnancy

Answer 15

Tissue hormones, role in initiation of labour
• Synthetic prostaglandins used to induce labour

Question 16

How does the mother increase uterine blood flow?

Answer 16

• Increasing cardiac output (CO)
• Reduced systemic blood pressure
• Reduced total peripheral resistance (TPR) - CO X TPR

= Increased uterine blood flow