Physiology of pregnancy Flashcards
what occurs to the fertilised ovum as it moves from the site of fertilisation (ampulla) to site of implantation (uterus)?
it divides and differentiates into a blastocyst
what occurs on days 3-5 of implantation?
Transport of the blastocyst into the uterus
what occurs on days 5-8 of implantation?
Blastocyst attaches to the lining of the uterus
what do the inner cells of the blastocyst develop into?
embryo
what do outer cells of blastocyst develop into?
the outer cells burrow into the uterine wall and become the placenta
role of hormones produced by placenta?
to maintain pregnancy
Describe how the blastocyst implants in the endometrium
The inner cells of the blastocyst develop into the embryo; the outer cells burrow into the uterine wall and become placenta
- When the free-floating blastocyst adheres to the endometrial lining, cords of trophoblastic cells begin to penetrate the endometrium - Advancing cords of trophoblastic cells tunnel deeper into endometrium, carving out a hole for the blastocyst - The boundaries between cells in the advancing trophoblastic tissue disintegrate
What tissue is the placenta derived fro,?
both trophoblast and decidual tissue
another name for trophoblast cells
choriom
what are syncytiotrophoblasts?
Trophoblast cells (chorion) differentiate into multinucleate cells (syncytiotrophoblasts)
-these invade decidua and break down capillaries to form cavities filled with maternal blood
How are placental Villi formed?
Trophoblast cell (chorion) differentiate into multinucleated cells (syncytriotrophoblasts) which invade decidua and break down capillaries to form cavities filled with maternal blood
Developing embryo sends capillaries into the syncytiotrophoblast projections to form ‘placental villi;
what does each placental villi contain?
Each villus contains fetal capillaries seperated from maternal blood by a thin layer of tissue (no direct contact between fetal and maternal blood)
what week of pregnancy are the placenta and fetal heart functional?
5th week of pregnancy
what cells are involved in early nutrition of the embryo?
Early nutrition of the embryo involves the invasion of trophoblastic cells into the decidua
what signals the corpus luteum to continue to secrete progesterone?
HCG signals the corpus luteum to continue secreting progesterone
What affect does progesterone have on decidual cells?
Progesterone stimulates decidual cells to. concentrate glycogen, proteins and lipids
what increases the contact area between uterus and placenta?
the placenta villi (hair-like projections)
-as the placenta develops they extend further into the uterine wall
what does the increased contact between the placenta and uterine wall through the placental villi allow?
more nutrients and waste material to be exchanged
where do blood vessels from the embryo develop?
in the placental villi
do the fetal and maternal blood make direct contact + explain
No direct contact between fetal and maternal blood
-a thin membrane seperated the embryo’s blood in the villi from the mother’s blood in the intervillous space
what does the circulation within the intervillous space partly act as?
arteriovenous shunt
What provides the foetus with oxygen and removal of CO2
The placenta
what does the exchange of oxygen and CO2 take place between?
Maternal (oxygen rich) blood and the umbilical blood (mixing of arterial and venous blood, oxygen- poor)
Is umbilical blood oxygen rich or oxygen poor and why?
Oxygen poor as it has a mix of arterial and venous blood
How does oxygen enter the fetal circulation system from the maternal circulation?
Oxygen diffuses from the maternal into the feta circulation system
How does CO2 leave the fetal circulating system?
Through a reversed gradient
How does fetal oxygen saturate blood return to the fetus?
via the umbilical vein
