The Menstrual Cycle

Front 1

Describe the special features of an egg cell

Back 1

1) Egg cell contains nutrients in the cytoplasm to feed the embryo
2)straight after fertilisation the egg's membrane changed its structure to stop any more sperm getting in. This makes sure the offspring ends up with the right amount of DNA.
3) the egg contains a haploid nucleus. this is so that when the egg is fertilised the resulting cell will have the right number of chromosomes.

Front 2

describe the features of a sperm cell

Back 2

1) sperm are small and have long tails so they can swim towards the egg.
2)sperm have lots of mitochondria in their middle section to provide the energy needed to swim the distance.
3)sperm also have an acrosome at the front of the head when the store the enzymes needed to digest their way through the membrane of the egg cell
4) sperm contains a haploid nucleus- one copy of each chromosome.

Front 3

what are the four stages of the menstrual cycle?

Back 3

stage one: day 1 is when the bleeding starts, the uterus lining breaks down and is released
stage two: the lining of the uterus builds up again from day 4 to day 14 ready to receive a fertilised egg.
stage three: around day 14 an egg is released from the ovary.
stage four: the lining is maintained for about 14 days until day 28. if there is no fertilised egg then the lining starts to break down again and the whole cycle starts over.

Front 4

what are the four hormones that control the menstrual cycle?

Back 4

FSH- follicle stimulating hormone
Oestrogen
LH- luteinising hormone
progesterone

Front 5

What effect does FSH have?

Back 5

1) caused a follicle ( an egg and it's surrounding cells) to mature in one of the ovaries
2) simulated oestrogen production

Front 6

what effect does oestrogen have?

Back 6

1) causes the lining of the uterus to thicken and grow
2) a high level stimulates an LH surge

Front 7

what effect does LH have?

Back 7

1) the LH surge stimulates ovulation at day 14- the follicle ruptures and the egg is released
2) stimulates the remains of the follicle to develop into a structure called a corpus luteum- which secretes progesterone.

Front 8

what effect does Progesterone have?

Back 8

1) maintains the lining of the uterus
2) inhibits (prevents) the production of FSH and LH
3) when the level of progesterone falls and theres a low oestrogen level the uterus lining breaks down
4) an low progesterone level allows FSH to increase and then the whole cycle starts again.

Front 9

what happens if the egg is fertilised?

Back 9

if a fertilised egg implants into the uterus then the levels of progesterone stay high to maintain the lining of the uterus. The uterus lining allows the placenta to develop. the placenta supplies the baby with oxygen, glucose and nutrients it needs to grow and removes its waste products

Front 10

how are the levels of hormones controlled?

Back 10

during the menstrual cycle the levels of different hormones in the blood are controlled by negative feedback.