Physiology of pregnancy

Question 1

what occurs to the fertilised ovum as it moves from the site of fertilisation (ampulla) to site of implantation (uterus)?

Answer 1

it divides and differentiates into a blastocyst

Question 2

what occurs on days 3-5 of implantation?

Answer 2

Transport of the blastocyst into the uterus

Question 3

what occurs on days 5-8 of implantation?

Answer 3

Blastocyst attaches to the lining of the uterus

Question 4

what do the inner cells of the blastocyst develop into?

Answer 4

embryo

Question 5

what do outer cells of blastocyst develop into?

Answer 5

the outer cells burrow into the uterine wall and become the placenta

Question 6

role of hormones produced by placenta?

Answer 6

to maintain pregnancy

Question 7

Describe how the blastocyst implants in the endometrium

Answer 7

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

Question 8

What tissue is the placenta derived fro,?

Answer 8

both trophoblast and decidual tissue

Question 9

another name for trophoblast cells

Answer 9

choriom

Question 10

what are syncytiotrophoblasts?

Answer 10

Trophoblast cells (chorion) differentiate into multinucleate cells (syncytiotrophoblasts)

-these invade decidua and break down capillaries to form cavities filled with maternal blood

Question 11

How are placental Villi formed?

Answer 11

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;

Question 12

what does each placental villi contain?

Answer 12

Each villus contains fetal capillaries seperated from maternal blood by a thin layer of tissue (no direct contact between fetal and maternal blood)

Question 13

what week of pregnancy are the placenta and fetal heart functional?

Answer 13

5th week of pregnancy

Question 14

what cells are involved in early nutrition of the embryo?

Answer 14

Early nutrition of the embryo involves the invasion of trophoblastic cells into the decidua

Question 15

what signals the corpus luteum to continue to secrete progesterone?

Answer 15

HCG signals the corpus luteum to continue secreting progesterone

Question 16

What affect does progesterone have on decidual cells?

Answer 16

Progesterone stimulates decidual cells to. concentrate glycogen, proteins and lipids

Question 17

what increases the contact area between uterus and placenta?

Answer 17

the placenta villi (hair-like projections)
-as the placenta develops they extend further into the uterine wall

Question 18

what does the increased contact between the placenta and uterine wall through the placental villi allow?

Answer 18

more nutrients and waste material to be exchanged

Question 19

where do blood vessels from the embryo develop?

Answer 19

in the placental villi

Question 20

do the fetal and maternal blood make direct contact + explain

Answer 20

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

Question 21

what does the circulation within the intervillous space partly act as?

Answer 21

arteriovenous shunt

Question 22

What provides the foetus with oxygen and removal of CO2

Answer 22

The placenta

Question 23

what does the exchange of oxygen and CO2 take place between?

Answer 23

Maternal (oxygen rich) blood and the umbilical blood (mixing of arterial and venous blood, oxygen- poor)

Question 24

Is umbilical blood oxygen rich or oxygen poor and why?

Answer 24

Oxygen poor as it has a mix of arterial and venous blood

Question 25

How does oxygen enter the fetal circulation system from the maternal circulation?

Answer 25

Oxygen diffuses from the maternal into the feta circulation system

Question 26

How does CO2 leave the fetal circulating system?

Answer 26

Through a reversed gradient

Question 27

How does fetal oxygen saturate blood return to the fetus?

Answer 27

via the umbilical vein