Component 2.3 - Pregnancy Flashcards
What are the 3 main functions of the amniotic fluid?
1) Maintains temperature
2) Protects the foetus during development e.g lubrication to prevent webbed toes
3) Acts as a shock absorber
What is the amnion?
A membrane that is derived from the inner cell mass of the blastocyst. The mother makes the amniotic fluid initially but from 4 months the foetus contributes urine to it
What is the role of hCG?
1) Developing embryo secretes before implantation and then it is secreted by the placenta
2) It maintains the corpus luteum which secretes progesterone and oestrogen to maintain the endometrium
Why is it important that hCG maintains the corpus luteum?
Oestrogen and progesterone remain at high concentration until the end of pregnancy. Which inhibits secretion of:
1) FSH - no follicles mature
2) LH - ovulation is not possible
3) Prolactin - so no milk is made
What does oestrogen stimulate the growth of during pregnancy?
1) The growth of the uterus to accommodate the growing foetus
2) The growth and development of mammary glands
What other hormone does the high level of progesterone inhibit and why is this important?
Inhibits oxytocin, which suppresses the uterine walls ability to contract
How do hormone levels change before birth?
Oestrogen levels increase and progesterone levels decrease - the uterine wall can now contract
Due to the low levels of progesterone at the end of pregnancy what is no longer inhibited and what does this mean?
Oxytocin - secreted by posterior pituitary gland stimulates contractions of the uterine wall which stimulates the secretion of more oxytocin (positive feedback)
Prolactin - secreted by anterior lobe of pituitary gland and after birth to stimulate the production of milk by the mammary glands
What else does the placenta secrete?
Oestrogen and progesterone giving them high concentrations in the plasma
