11) Endocrinology of pregnancy

Question 1

Which enzyme converts testosterone to oestrogen?

Answer 1

Aromatase

Question 2

2 symptoms of someone with an aromatase deficiency?

Answer 2

Excess testosterone=acne + hirturism

Lack of oestrogen=tall as oestrogen req to close growth plates + osteoporosis

Question 3

4 components of semen:

Answer 3

12-120million spermatozoa (only 1 million reach ovum)
Seminal fluid
Leucocytes
(viruses)

Question 4

2 places that produce seminal fluid:

Answer 4

1) epidiymis

2) accessory sex glands e.g. seminal vesicles

Question 5

5 steps in fertilisation:

Answer 5

Capcitation
Acrosome reaction
Fertilisation
Cortical reaction
Implantation (attachment + decidulisation)

Question 6

What is sperm capcitation with examples of the changes that take place?

Answer 6

Sperm achieving the capability to fertilise an egg

• whiplash tail develops
• loss of glycoprotein coat

Question 7

Where does sperm capacitation take place?

Answer 7

Fallopian tube

Question 8

What happens during the acrosome reaction?

Answer 8

When the digestive head of the sperm penetrates the ovum

• Sperm binds to ZP3 receptors on ovum
• Ca2+ influx into acrosome (due to progesterone)
• digestive enzymes released=sperm penetrates

Question 9

Where does fertilisation take place?

Answer 9

Fallopian tube

Question 10

What is the cortical reaction?

Answer 10

Hardening of the zona pellucida to prevent further fertilisation of ovum by more than 1 sperm
-ZP3 receptors on ovum surface degraded=no sperm receptors left

Question 11

What is the first stage in the development of the conceptus:

Answer 11

Free living phase (9-10 days)

• moving from fallopian tube to uterus
• gets nutrition from uterine secretions

Question 12

2 stages in implantation:

Answer 12

1) attachment-outer trophoblast cells make contact with uterine endometrium
2) decidualisation-endometrial changes due to progesterone

Question 13

3 factors involved in implantation:

Answer 13

LIF
IL-11
Progesterone

Question 14

How do hormones during pregnancy change?

Answer 14

HcG-high until about 40 days (maintains corpus luteum-but then there is the luteo-placental shift)
Oestrogen + progesterone increase throughtout
Lactogen increases

Question 15

What is the main oestrogen during pregnancy?

Answer 15

Oestriol

Question 16

What is the purpose of lactogen in pregnancy?

Answer 16

changes metabolism e.g. makes mother more insulin resistance so more glucose to foetus as mother can handle higher glucose levels

Question 17

What happens to the pituitary gland during pregnancy?

Answer 17

Increases in size due to lactotrophs increasing in size

Question 18

Why can’t elevated prolactin be used as a test for a prolactinoma if someone is pregnant?

Answer 18

Prolactin levels are increased in pregnancy

Question 19

3 things oxytocin causes:

Answer 19

Uterine contractions
Cervical dilation
Milk ejection

Question 20

What is the stimulus for lactation?

Answer 20

Suckling

Question 21

What can high prolactin levels cause in men + women?

Answer 21

Men=loss of libido

Women=amenorrhoea

Question 22

What are the 2 hormones req for lactation?

Answer 22

Oxytocin=milk ejection

Prolactin=milk synthesis