The Menstrual Cyle Flashcards
What happens to the structure of the egg after it is fertilised, and why does it happen?
The eggs membrane hardens to prevent any more sperm from getting in. This make sure that the offspring end up with the right amount of Chromosomes.
What does an egg contain in its cytoplasm, and why?
Nutrients, to feed the embryo
Does the egg contain a haploid or a diploid nucleus?
Haploid - this is so that the zygote will have the right amount of chromosomes when fertilised.
What two features help a sperm swim?
It’s small size, and long tail.
What do sperm contain in the ‘middle section’, and why do they have it?
Lots of mitochondria, in order to give them the energy (from respiration) to swim the long distance.
What do sperm have at the tip of their head, and why do they have it?
An Acrosome - this is used to store enzymes they need to digest their way through the membrane of the egg cell
Do sperm have a diploid or haploid nucleus?
Haploid (one cope of each chromosome)
Briefly explain the 4 main stages of menstruation.
Stage 1 - lining of the uterus breaks down
Stage 2 - lining of the uterus builds back up
Stage 3 - egg is released from ovary (day 14)
Stage 4- lining of the uterus is then maintained for 14 days
What is FSH and what does it do?
Give two
Follicle stimulating hormone:
>It causes the follicle to mature
>Stimulates oestrogen production
What role does oestrogen have in the menstrual cycle?
1) It causes the lining of the uterus to thicken and grow
2) A high level stimulates an LH surge (a rapid increase)
What does LH stand for?
Luteinising hormone
What does LH do?
Give two
1) The LH surge stimulates ovulation (day 14)
2) Stimulates the follicle to develop into a corpus luteum (which secretes progesterone)
What does progesterone do and where is it secreted?
Give 4 points, and where it’s secreted
1) Maintains the lining of the uterus
2) Inhibits the production of FSH and LH
3) When the level of progesterone falls, and there’s a low oestrogen level, the uterus lining breaks down.
4) A low progesterone level allows FSH to increase.. The whole cycle then starts again
Secreted by corpus luteum
In what situation would progesterone carry on being released?
When a woman becomes pregnant.
What hormone carries on being released when a woman becomes pregnant?
Progesterone
