Hormones

Hormones

Chemical messengers sent in the blood
1. Carried in blood plasma to other parts of the body
  1. Only affect target cells in particular places
    1. Have long lasting effects
2. Control things in organs and cells that need constant adjustment
Produced in and secreted by various glands
1. The pituitary gland
  1. Produces important hormones including FSH and LH
2. Ovaries
  1. Produce oestrogen
    1. Involved in menstrual cycle
Difference between nerves and hormones
1. Nerves
  1. 1) Very FAST action 2) Act for a SHORT TIME 3) Act on a PRECISE AREA
2. Hormones
  1. 1) SLOWER action 2) Act for a LONG TIME 3) Act in a GENERAL way
Menstrual cycle
1. Four stages
  1. Day 1 is when the bleeding starts. The uterus lining breaks down for about four days
    1. The lining of the uterus builds up again from day 4 to 14 into a thick spongy layer full of blood vessels, ready to receive a fertilised egg
      1. An egg is released from the ovary at day 14
        The wall is then maintained for about 14 days, until day 28. If no fertilised egg has landed on the uterus wall by day 28 the spongy lining starts to break down again and the whole cycle starts again
2. Three main hormones
  1. FSH (Folicle-Stimulating Hormone)
    2. Causes an egg to mature in one of the ovaries
    3. Stimulates the ovaries to produce oestrogen
  2. LH (Luteinsing Hormone)
    1. Produced by the pituitary gland
    2. Stimulates the release of an egg at around the middle of the menstrual cycle
  3. Oestrogen
    1. Produced in the ovaries
    2. Causes pituitary to produce LH
    3. Inhibits further release of FSH
Reducing fertility
1. Oestrogen
  1. Taken everyday egg development and production stop
2. Progesterone
  1. Stimulates the production of thick cervical mucus which prevents sperm getting through
3. The pill
  1. First made in 1950s and contained high levels of oestrogen and progestorone
    1. Link between blood clots so lower doses of oestrogen now
IVF
1. Involves collecting eggs from ovaries and fertilises them in a lab using sperm. These are grown into embryos
  1. Once embryos are grown the best are transferred to the womb to improve chance of pregnancy
    1. FSH nad LH are given before egg collection to stimulate egg production
2. Pros
  1. Give infertile couples a child
3. Cons
  1. Strong reaction to hormones eg. abdominal pain, vomiting, dehydration
  2. Increased risk of cancer
  3. Multiple births
  4. Expensive and doesn't always work

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	Created by Tia Eve over 8 years ago

	Copied by Peddaraju Penchala Prasad almost 8 years ago