Physiology of pregnancy

Question 1

Describe the duration of human pregnancy?

Answer 1

280 days (40 weeks) from last menstrual period

266 days (38 weeks) from fertilisation

Question 2

How is foetal age estimated?

Answer 2

Length and US measurements of foetus

Question 3

Describe the physical signs of pregnancy?

Answer 3

Cessation of mestruation

Morning sickness

Increased frequency of urination

Increased breast size

Fatigue

Darkening of areolae

Question 4

How is pregnancy determined biochemically?

Answer 4

Human chorionic gonadotropin in blood and urine

Question 5

Where does hCG arise from?

Answer 5

Produced by trophoblast

Question 6

Why are physiological adaptations required in pregnancy?

Answer 6

Maintain uteroplacental perfusion

Maintain foetal demands

Question 7

What are the functions of the umbilical veins and arteries?

Answer 7

Umbilical vein carries well-oxygenated blood to the embryo

Umbilical arteries return embryoinic blood to placenta

Question 8

How does material from the mother reach the embryo/foetus?

Answer 8

Placenta

Some material via diffusion, other materials must be transported

Question 9

Which organs does the placenta substitute for in utero?

Answer 9

Lungs

Kidneys

GIT

Question 10

Describe the endocrine function of the placenta?

Answer 10

hCG: rescues corpus luteum

Human placental lactogen: breast development, maternal metabolic effects

Oestrogen and progesterone: pregnancy maintenance and breast development

Question 11

Describe the difference between monozygotic and dizygotic multiple pregnancies?

Answer 11

Monozygotic: single fertilised ovum, genetically identical

Dizygotic: 2 oocytes ovulated and fertilised by 2 separate sperm, not genetically identical

Question 12

Describe the changes to the cervix prior to parturition?

Answer 12

Softening

Question 13

Describe the changes that occur to the reproductive system during labor?

Answer 13

Rhythmic uterine contractions

Cervical dilation

Question 14

How are the uterine contractions maintained during labor?

Answer 14

Positive feedback

Question 15

What occurs during parturition after the baby is delivered?

Answer 15

Placental release and expulsion

Question 16

Descirbe the regulators of parturition?

Answer 16

Trigger for labor unknown

Stretch of cervix stimulus

Oxytocin

Positive feedback

Question 17

Describe the mammary gland development in puberty, pregnancy and late pregnancy?

Answer 17

Puberty: oestrogen stimulates growth of ducts and fat deposition

Pregnancy: oestrogen, GH and cortisol stimulate further gland development

Late pregnancy: progesterone stimulates conversion of ducts to secretory epithelium

Question 18

Describe lactation before birth?

Answer 18

Prolactin-inhibiting hormone blocks prolactin

High sex steroid levels supres milk production

Question 19

Describe lactation after birth?

Answer 19

High prolactin and low oestrogen > lactation

Question 20

Describe the effect of suckling?

Answer 20

Inhibits prolactin inhibiting hormone > prolactin > milk production

Oxytocin > milk ejection

Inhbits GnRH and ovarian cycle

Question 21

Why does suckling inhibit GnRH and the ovarian cycle?

Answer 21

Want all of the energy going into breastfeeding, not carrying another child

Question 22

Describe the hormonal control of milk secretion and release?

Answer 22