development and birth

Question 1

what is the first part of the menstrual cycle

Answer 1

menses- this is the removal of superficial layer of endometrium.

Question 2

what happens in the females system during menses

Answer 2

-the hypothalamus releases GnRH. it stimulates the anterior pituitary gland to produce LH and FSH.
- the ovary matures
- while the ovary is maturing, it is producing oestrogen and a bit of progesterone. it determined wither you inhibit or not inhibit the hyapothalamus
- the thickens lining from the progesterone is sloughed off.

Question 3

what is the role of progesterone

Answer 3

thickens the uterus lining for implantation

Question 4

what is the second part of the menstrual cycle and what does this mean

Answer 4

proliferative stage. the uterine lining thickens again. the effect will begin to develop again and produce oestrogen and some progesterone. his stimulates the hypothalamus to secrete GnRH which stimulates the anterior pituitary gland to produce LH FSH. when LH reaches tis peak, that marks the day of ovulation. the secondary oocyte is released and the the other is used as energy. the corpus lutetum is left and it maintains the up regulation of the uterine wall. it also inhibits the hypothalamus from producing GnRH

Question 5

explain the role of FSH

Answer 5

it stimulates the development of the follicle so more eostrogen is produced and therefore more GnrH (positive feedback)

Question 6

what triggers ovulation

Answer 6

day 14 when the LH reaches its peak.

Question 7

what happens when the oocyte is released

Answer 7

it becomes haploid.

Question 8

explain the secretory stage

Answer 8

this is third stage after proliferatory. the body start producing more progesterone rather than oestrogen and FSH and LH is dramatically reduced. the endometrium continues to thicken. the endometrium is also differentiating to support the implantation of the embryo and secrete enzymes to help the sperm to meet the egg.

Question 9

when does fertilisation occurs

Answer 9

day 7-8

Question 10

what happens when implantation occurs

Answer 10

the outer layer of the embryo makes contact with the uterine wall, it triggers the development of a placenta. this placenta will secrete human chorionic gonadotrophin (HCG). it will send inhibitory signals to the hypothalamus to stop it from producing GNRH.

Question 11

what does progesterone do and why does it begin to increase after ovulation

Answer 11

it helps to thicken the endometrium walls and inhibits the hypothalamus to produce GnRH

Question 12

what do we look for during pregnancy tests

Answer 12

HCG - human chronic gonatoropin

Question 13

what happens when fertilisation does not occur

Answer 13

the corpus luteum starts to degenerate and this stops production of progesterone and therefore nothing inhibits the hypothalamus from making GnRH and Lh and FSH production begins and it starts again.

Question 14

explain the fertilisation process

Answer 14

sperm: capacitation in the uterus (enzymes) - stabilise acrosomal head and strengthen tail motility
egg: secondary egg released into the uterine duct’ fallopian tube

Question 15

explain the parts of blastocyst

Answer 15

it has trophoblast - differentiated cell which allow the embryo to implant uterine wall and form the placenta. the inner cell mass contains the true embryo which will form the foetus. the cavity will form the amoetic sac

Question 16

explain fertilisation in day 0- how do we just have one sperm make contact

Answer 16

when the sperm receptor makes connection to the surface of the oocyte, it will trigger the first reaction:
1. fast block: it changes the polarity of the cell. the zone elucidate of the secondary oocyte thickens. it polarises the cell with entry of the sodium
2. slow block: as a result of this polarisation, the endoplasmic reticulum will release calcium ions which will trigger the second oocyte to complete meiosis 2. you will have the two cells where one become the fertilised oocyte and the other become the polar body which degenerates and used as energy by the second oocyte.

Question 17

explain what happens after fertilisation

Answer 17

this is known as cleavage. the zygote undergoes repeated mitotic division as it goes through the fallopian tube and enters the uterus. when it enters the morals stage, the zona pellucid is still present but the density o the cell triggers the cell to differentiate. the outer layer becomes the trophoblast and the inner cell starts to secrete fluid- zona hatching ( facilitates the trophoblast implanting the uterine wall. just before implantation, we get the blastocysts then it biomes the trophoblast

Question 18

what needs to happen for the cell to become a zygote

Answer 18

the pronucleus of the sperm and the egg fuses

Question 19

explain implantation

Answer 19

happens around day 7-10. the trophoblast starts to cause differentiation. it begins to connect with the uterus lining (precursor to the placenta). around day 12, the placenta is formed and the inner cell mass changes. the true embryo starts to form. this is called the emrbyonic disc. it has different layers which is gastrulation

Question 20

explain gastrulation

Answer 20

it happens in the the embryonic disk. it develops from the inner cell mass. it has ectoderm and endoderm. the top half of the embryonic disk form the amniotic sac and the bottom part form the gut. the top part of the ectoderm is the epiblast. the primitive streak provides the axis of the developing true embryo. mitotic division of the ectoderm occurs here. and the mesoderm will migrate to the primitive streak. this will form the third layer which is the mesoderm. these three cells, (ectoderm, endoderm and mesoderm are nor plutipotent) they cannot change.

Question 21

the inner cell mass or the trophoblast it totipotent, what does it mean

Answer 21

it means that they’re stems ells that can differentiate to any cells- ectoderm, endoderm.

Question 22

explain ectoderm, endoderm and mesoderm

Answer 22

in the cell mass while its a trophoblast, these cells are totipotent, when it reaches the gastrulation stage, they become pluripotent.
ectoderm: skin and nervous sytem
endoderm: digestive system
mesoderm; organs, muscles and bone

Question 23

explain neurulation

Answer 23

happens around day 18. the ectoderm at the top and the mesoderm and the endoderm.
the mesoderm will begin to form structures. it forms three structures- somites (organs, muscles and bones), notochord (tubing, important in triggering the overlying ectodermal cells to undergo repeated mitotic division. this results to the ectodermal cells folding in and pinching off. when the tubing is formed, the ectoderm folds the tail and head folds the opposite edirection.

Question 24

in neurolation during the primitive steak where the mesoderm folds and determines the brain and the skeleton what happens to their grey and white matter

Answer 24

the grey and white matter switches

Question 25

explain the organogenesis

Answer 25

happens between week 3 to week 8 and continue until birth. brain and heart develops first and the kidneys. your transition naming it as embryo to a foetus because of organs develop

Question 26

explain the parturition process

Answer 26

1. the expanding of the uterine wall and the feats will send signals to the maternal anterior pituitary gland. the head of the foetus will push up agains the cervix but also the foetus. their immature pituitary gland will react to the stress and secrete ACTH (stimulates the adrenocorticotoprotic hormone) which stimulus the fetal adrenal gland to secrete adrenal cortical steroids

Question 27

what does adrenal cortical steroids do

Answer 27

2 and 3. its released by the umbilical cord to the placenta it matures the lungs preparing the foetus so when it is birthed, it can breathe on its own. 4: it also converts placental progesterone to oestrogen to increase uterine contraction - (stimulate hypothalamus) and up regulate oxytocin receptors in the uterus and up regulate protagladin synthesis to relax cervix to open up. 5. uterine wall of the mother is stretched because sensory receptors send signals to the anterior pituitary gland which 6. releases oxytocin - stimulates muscle contraction). 7. birth