The Menstrual Cycle and Contraception Topic 5 - Homeostasis

• where are hormones released

  by the pituitary gland into the blood
• what hormone do the ovaries produce


  oestrogen
• process of ovulation

  - pituitary gland produces FSH which causes the egg to mature in the follicle, in the ovary

  - as egg develops inside follicle, the follicle produces hormone oestrogen

  - oestrogen repairs and grows uterus lining, and inhibits (stops) FSH

  - When oestrogen rises to high enough level it causes a surge in LH from the pituitary gland, which causes ovulation, and an egg is released from the follicle (day 14 of cycle)

  - the follicle then becomes the corpus luteum, and produces oestrogen and progesterone, which both inhibit FSH and LH production from the pituitary, example of negative feedback

  - progesterone then maintains uterus lining

  - if egg is not then fertilized, then the corpus luteum dies and progesterone levels drop, which causes maintenance of uterus lining to break down, this is called a period
• follicle


  the fluid sac in the ovary in which the egg develops
• corpus luteum


  remains of the follicle after it has released egg into fallopian tube, secretes hormones in menstrual cycle
• FSH


  Follicle stimulating hormone, secreted from pituitary gland, causes an egg to mature in the ovary and stimulates ovaries to release oestrogen.
• oestrogen

  Inhibits secretion of FSH, (so only 1 egg matures in a cycle), repairs, thickens and maintains uterus lining. Stimulates pituitary gland to secrete LH.
• LH


  Luteinising hormone, triggers ovulation, secreted from pituitary gland.
• Progesterone


  Produced in ovaries, maintains uterus lining during latter part of menstrual cycle and pregnancy.
• hormonal methods of contraception

  - oral contraceptive (the pill), contains progesterone and oestrogen which inhibit FSH, so egg can't mature, very effective, however changes in weight, mood, and blood pressure due to high levels of oestrogen

  - injections and patches can also be used which produce progesterone to inhibit maturation of eggs
• non hormonal methods of contraception

  - condoms, quick and easy, can break/rip

  - IUD, fitted by health professional and last long time, can cause utopic pregnancy

  - spermicide

  - surgical methods e.g. vasectomy, these are permanent
• IVF


  in vitro fertilization, bringing sperm and egg together to create an embryo, which is placed in the woman's womb and increases chance of giving birth

  - the eggs are fertilized in a lab in a petri dish

  - very expensive, might result in twins/ triplets as multiple embryos being inserted