Physiology of Pregnancy Flashcards
What is the duration of human pregnancy?
38 weeks from fertilisation
What are the physical signs of pregnancy?
cessation of menstruation, morning sickness, increased frequency of urination, increased size of breasts, fatigue, darkening of areolae
What is the biochemical test for pregnancy?
hCG
What is the umbilical vein?
the blood vessel in the umbilical cord which carriers oxygenated blood from the placenta to the baby
What are the umbilical arteries?
the two blood vessels in the umbilical cord which carry deoxygenated blood from the baby to the placenta
Why are blood lakes in the placenta important?
so that fetal blood supply is not subject to vasoconstriction
What are the functions of the placenta?
substitutes for fetal lungs, gastrointestinal tract and kidneys and regulates uteroplacental blood flow
What hormones are produced by the placenta?
human chorionic gonadotropin, human placental lactogen, oestrogen and progesterone
What is the role of oxytocin in parturition?
cervical stretch stimulates the release of oxytocin from the posterior pituitary which stimulates release of prostaglandins and uterine contraction which stimulates cervical stretch which stimulates release of oxytocin - positive feedback loop
Why do breach pregnancies often need a caesarian section?
because the head won’t stretch the cervix sufficiently
What happens to mammary glands in puberty?
oestrogen stimulates growth of ducts and fat deposition
What happens to mammary glands in pregnancy?
oestrogen, growth hormone and cortisol stimulate further gland development
What happens to mammary glands in late pregnancy?
progesterone converts the ducts into a secretory epithelium
What inhibits lactation before birth?
prolactin inhibiting hormone blocks prolactin and high sex steroid levels block milk production
What are the effects of suckling?
inhibits PIH, stimulates oxytocin, inhibits GnRH
