Physiology of Pregnancy Flashcards
What is a blastocyst?
embryo which has developed 2 different cell compartments and a fluid cavity (inner and outer cell masses)
What days post fertilisation is the blastocyst transported into the uterus?
3-5 days
How many days post fertilisation does the blastocyst attach to the lining of the uterus?
5-8days
What happens when the blastocyst adheres to the endometrial lining?
cords of trophoblastic cells begin the penetrate the endometrium
What happens to the boundaries between the cells fo the advancing trophoblastic tissue?
begin to disintegrate
How many days post fertilisation is the blastocyst buried in the uterine lining?
day 12
What is the placenta derived from?
trophoblast and decidual tissue
What type of trophoblast cell invade the decidua and break down capillaries to form cavities filled with maternal blood?
syncytiotrophoblasts
What froms the placental villi?
developing embryo send capillaries into the syncytiotrophoblast projections
What is found within the placental villi?
foetal capillaries separated from maternal blood by a thin membrane within the intervillous space
When is the placenta functional?
5th week of pregnancy
What is the function of progesterone in relation to the decidual cells?
stimulates decidual cells to concentrate glycogen, proteins and lipids
What is the purpose of the placental villi?
increase surface area
What are the 3 factors that faciliatate oxygen transport in the fetus?
fetal HB (higher affinity to o2); higher Hb conc. in fetal blood and Bohr effect (fetal Hb can carry more o2 in low pCO2 than in high pCO2
What is the pupose of the Bohr effect?
Oxygen has a lower affinity when there is high CO2 conc. or low pH which means that in metabolically active tissues eg SK muscle, more oxygen is unloaded in response to higher CO2 in that region
How does glucose pass the placenta?
simplified transport
What is the function of hCG?
prevent involution of the corpus luteum; effect on testes of male fetus
When is hCS produced?
from week 5 of the pregnancy
What are the function of human chorionic somatomammotropin?
growth hormone-like effects-protein tissue formation; decreases insulin sensitivity in mother- more glucose for fetus; breast development
What is the function of progesterone in pregnancy?
development of decidual cells; decreases uterine contractility; prep for lactation
What is the function of estrogen in pregnancy?
enlargemnt of uterus; breast devleopment; relaxation of ligaments
What is the significance of estriol level in pregnancy?
indicator of vitality of fetus
What is the function of placental CRH?
results in aldosterone–HT; cortisol–oedema; insulin resistance
What causes hyperthyroidism in pregnnacy?
placenta produces human chorionic thyrotropin which functions similar to TSH
What causes hyperparathyroidism in pregnancy?
increased calcium demands by the placenta
Why is there an increase in CO during pregnancy?
demands of uteroplacental circulation
When does CO decrease during pregnancy?
alst 8 weeks
Why does CO dcrease at end of pregnancy?
sensitive to body position-uterus compresses IVC when supine