Physiology of pregnancy and partition:

Question 1

Outline the placental clock concept:

Answer 1

1) Increasing amounts of Corticotrophin Releasing Hormone (CRH) towards term
2) Stimulates foetal pituitary to release ACTH
3) ACTH increase foetal adrenal DHEA screation
4) DHEA is major oestrogenic precursor
5) Oestrogens stimulate increases in myometrial gap-junction protein numbers
6) Facilitates regular, coordinated uterine contractions

Question 2

What mediates the increase Ca2+ stores in the myometrium?

Answer 2

Oxytocin. Stimulates contraction

Question 3

What clinical analogues are used to induce labour?

Answer 3

Syntocinon/Pitocin

Question 4

What stimulates oxytocin release?

Answer 4

• Cervical stimulation/myometrium stretch

- Positive feedback - Ferguson Reflex

Question 5

List 4 requirements for partition:

Answer 5

• Inflammatory mediators
• Elevations in intra-cellular Ca2+ levels and myocyte depolarisation
• Changes in uterine sensitivity to progesterone

Question 6

List 3 drugs that can be used to inhibit uterine contractions:

Answer 6

• Beta-2 mimetics
• Nifedipine
• Progesterone

Question 7

List 2 drugs to promote uterine contraction:

Answer 7

• Syntocinon
• Ergometrine - alpha2 agonists
• Misoprostol - prostaglandin mimetics