Physiology of labour

Question 1

What is the weight + capacity of an empty uterus?

Answer 1

Weight - 50g

Capacity - 10ml

Question 2

What is the weight + capacity of a pregnant uterus?

Answer 2

Weight - 800 - 1200g

Capacity - 5L

Question 3

Which type of cell adaptation is initially seen in the uterus in pregnancy?

Which hormone regulates this?

Answer 3

Hyperplasia

Oestrogen

Question 4

Which type of cell adaptation is subsequently seen in the uterus in pregnancy?

Answer 4

Hypertrophy

Question 5

During pregnancy, do levels of cAMP increase or decrease?

Answer 5

Increase

Question 6

What are the 3 layers of the myometrium and the direction of the muscle fibres?

Answer 6

Outer - longitudinal

Middle - criss-cross

Inner - circular

Question 7

Which motor protein is responsible for uterine muscle contraction?

Answer 7

Myosin II

Question 8

In uterine contraction, what does calcium bind to?

Answer 8

Calmodulin

Question 9

In uterine contraction, which enzyme phosphorylates myosin?

Answer 9

Myosin light chain kinase

Question 10

In uterine contraction, what does the binding of calcium to calmodulin activate?

Answer 10

Myosin light chain kinase

Question 11

In uterine contraction, how is myosin light chain kinase activated?

Answer 11

Binding of calcium to calmodulin

Question 12

During cervical ripening, what happens to the level of collagen?

Which substance causes this?

Answer 12

Collagen decreases

Prostaglandins

Question 13

During cervical ripening, which specific form of collagen is replaced with what?

Answer 13

Dermatan sulphate

Hyaluronic acid

Question 14

What happens to the levels of CRH-BP in late pregnancy?

Answer 14

CRH-BP levels reduce

Question 15

During labour, which factor triggers oxytocin release?

Answer 15

Stretch of the cervix

Question 16

Which synthetic form of oxytocin can be used to induce labour?

Answer 16

Syntocinon

Question 17

What are the 2 key prostaglandins in labour?

Answer 17

PGF2a
PGE2

Question 18

Which structure protects the foetus from the mother’s immune system?

Answer 18

Decidua

Question 19

In the foetus, which type of hormone helps the lungs develop?

Answer 19

Glucocorticoids

Question 20

In which part of the uterus are contractions the strongest?

Answer 20

Fundus

Question 21

Define a first degree obstetric laceration.

Answer 21

Tear in skin + underlying superficial tissues (excluding muscle)

Question 22

Define a second degree obstetric laceration.

Answer 22

Tear involving perineal muscle damage

Question 23

Define a third degree obstetric laceration.

Answer 23

Involves the muscle of the external anal sphincter

Question 24

Define a fourth degree obstetric laceration.

Answer 24

External and internal anal sphincter become completely divided

Question 25

What is meant by the puerperium?

Answer 25

Time after birth where maternal physiology is returning to pre-pregnant state

Question 26

Which type of discharge is normal from the uterus after birth?

Answer 26

Lochia