menstrual Cycle and Pregnancy Flashcards
What are the first 2 stages of the Menstrual Cycle?
Stage 1 Day 1 - MENSTUATION BEGINS. tHE UTERUS LINING BREAKS DOWN FOR ABOUT 4 DAYS.
Stage 2 Day 4-14, the uterus lining builds up again into a thick spongy layer full of blood vessels , ready for a fertilised egg.
What are the second 2 stages of the Menstrual Cycle?
Stage 3 Day 14. An egg developes and is released from the ovary at day 14 - this is called OVULATION.
Stage 4 Day 14-28. The wall is maintained. If no fertilised egg has landed on the uterus wall by day 28 the spongy lining starts to break down and the whole cycle starts again.
Name the 4 hormones that control the Menstrual Cycle.
FSH (Follicle stimulating hormone)
Oestrogen
LH (Luteinising Hormone)
Progesterone
What does FSH do?
- produced in the pituitary gland
- causes an egg to mature in one of the ovaries in a follicle
- stimulates the ovaries to produce oestrogen
- oestrogen then inhibits the release of FSH
What does OESTROGEN do?
- produced in thr ovaries
- causes the lining of the uterus to grow
- stimulates the release of LH which causes the egg to grow
What does LH do? (Luteinising hormone)
- produced by the pituitary gland
- stimulates the release of an egg at day 14 (OVULATION)
What does PROGESTERONE DO?
produced in the OVARIES by the remains of the follicle after ovulation
- maintains the lining of thr uterus during the second half of the cycle. When the level of progesterone falls, the lining breaks down
- inhibits the release of LH and FSH
What helps the embryo alive and growing?
Once the embryo has implanted the PLACENTA develops - this lets the blood of the embryo and mother get very close to allow the EXCHANGE of FOOD, OXYGEN and WASTE.
What protects the embryo?
The AMNION which encapsulate the embryo which is full of amniotic fluid. This protects the embryo against knocks and bumps
