Reproductive system

Question 1

What are the elements of the hypothalamic-pituitary-gonadal axis?

Answer 1

Gonadotrophin releasing hormone (GnRH) is released by the hypothalamus, this stimulates LH and FSH release from the pituitary
These act on the ovaries to stimulate follicle development
The theca granulosa cells around the follicles release oestrogen that negatively feeds back to the hypothalamus and pituitary suppressing LH and FSH release

Question 2

What are the actions of oestrogen?

Answer 2

Released by ovaries in response to LH and FSH
Breast development
Growth and devleopment of vulva, vagina and uterus at puberty
Blood vessel development in the uterus
Development of the endometrium

Question 3

Where is progesterone produced and what are its actions?

Answer 3

It is produced by the corpus luteum after ovulation or by the placenta during pregnancy
It acts on tissues that have previously been acted on by oestrogen
Maintains the endometrium
Thickens cervical mucus
Increase body temperature

Question 4

Why can puberty start earlier in obese girls?

Answer 4

Aromatase present in adipose tissue and is important for creating oestrogen

Question 5

What are the tanner stages?

Answer 5

1 - under 10 - no pubic hair or breast buds
2 - 10-11 - light and thin pubic hair, breast buds behind areola
3 -11-13 - coarse pubic hair, breast buds spread beyond areola
4 -13-14 - Adult like pubic hair but not reaching thigh, areolar mound forms and projects from surrounding tissue
5 - above 14 - hair entending to medial thigh, areolar mounds reduce and adult breasts form

Question 6

What are the hormonal changes during puberty?

Answer 6

GnRH starts getting released by the hypothalamus
FSH levels plateau around a year before menarche
LH levels rise until just before menarche

Question 7

What are the two phases of the menstrual cycle?

Answer 7

There is the follicular phase (1st 14 days) and luteal phase following ovulation (second 14 days)

Question 8

What are the four stages of follice development?

Answer 8

Primordial follicles
Primary follicles
Secondary follicles
Antral follicles

Question 9

What hormone is required for secondary follicles to mature into antral follicles?

Answer 9

FSH

Question 10

What is the role of lutenising hormone?

Answer 10

It spikes just before ovulation to cause release of the egg

Question 11

When does ovulation occur in the menstural cycle?

Answer 11

14 days before end of cycle e.g. day 16 of a 30 day cycle

Question 12

What day of the cycle does menstruation occur?

Answer 12

Menstruation starts on day 1 of the cycle

Question 13

What is the cause of mittelschmerz?

Answer 13

This is mid cycle pain caused by blood irritating the peritoneum from ovulation

Question 14

Following ovulation what hormone changes occur?

Answer 14

There is an increase in progesterone to maintain the lining of the uterus
When this progesterone production is not taken over by the placenta then endometrial cells undergo apoptosis

Question 15

Why does menstrual blood not clot?

Answer 15

Plasmin prevents it from clotting

Excessive clotting is a sign of menorrhagia as there was not time for the plasmin to lyse the fibrinogen

Question 16

What are the actions of FSH?

Answer 16

Prepares the follicle of the month
Increases aromatase synthesis
Increases synthesis of LH receptors

Question 17

What are the actions of LH?

Answer 17

Synthesis of testosterone for conversion by aromatase to estrdiol in the granulosa

Question 18

What hormone changes occur during pregnancy?

Answer 18

hCG is synthesised by the syncytiotrophoblast in the placenta
This acts as an LH analogue to maintain the corpus luteum which synthesis progesterone
Progesterone is important for maintaining pregnancy

Question 19

How do oral contraceptive pills work in terms of hormones?

Answer 19

Baseline levels of oestrogen prevent the midcycle oestrogen surge hence preventing LH surge and ovulation
Progesterone arrest the prolifertive phase causing gland atrophy and inhibit LH preventing ovulation

Question 20

What are the two main types of oestrogen and what effects do they have?

Answer 20

Estradiol is the main type in non pregnant women:
-Principally derived from ovaries
-Primary hormone responsible for the prolifertive (follicular) phase of the menstrual cycle
-Stimulates growth in the endometrium
-Stimulates elongation of the spiral arteries
-causes cervical mucus to become watery to allow passage of sperm
-stimulates growth and development of female reproductive system
Estriol is the main type in pregnancy
-derived from maternal liver

Question 21

What is the role of sex hormone binding globulin and what conditions effect its production?

Answer 21

It is synthesised in the liver and binds to testosterone and oestrogen
Androgens, obesity and hypothyroidism decrease its synthesis
This results in more free testosterone as less is being bound, hence causing hirsutism

Question 22

What are the normal changes that are seen in pregnancy?

Answer 22

There is an increase in plasma volume and red cell mass:
-This causes a drop in haemoglobin by dilutional effect
-Increases the GFR and hence the clearnace of urea and creatinine
Respiratory alkalosis - due to progesterone stimulating resp centre, results in more O2 for fetus and a fall in
co2
Increased serum T4 and cortisol
-due to increased production of binding hormones
-No increase in free hormones so no clinical signs of overactivity