Control In The Human Body Flashcards
How do hormones work?
Many processes within the body are coordinates by chemical substances called hormones. Hormones are secreted by glands and are usually transported to their targeted organ by the bloodstream
What do hormones do?
They regulate the function of many organs and cells. E.g the monthly realises of an egg from a woman’s overlies and the changing in the thickness of the lining of her womb are controlled by hormones secreted by the pituitary gland and by the ovaries
Several hormones are involved in the menstrual cycle of a woman. What are the hormones that ire involved in promoting the release of an egg?
FSH (Follicle stimulating hormone) is secreted by the pituitary gland and causes egged to mature in the ovaries. It also stimulates the ovaries to produce hormones including oestrogen
Oestrogen is secreted by the ovaries and inhabits the further production of FSH. It stimulates the production of LH and also stimulate the womb lining to develop to receive the fertilised egg
LH (luteinising hormone) it is made by pituitary glands and stimulates the mature egg to be released in the ovary
What does IVF involve?
It involves giving the mother FSH and LH to stimulate the maturation of several eggs. The eggs are collected from the mother and fertilised by sperm from the father. The fertilised eggs develop into embryos. At the stage when they are tiny balls of cells, one or two embryos are inserts into the mother’s uterus (womb).
Give some example of internal conditions which are controlled:
The water content of the body-water leaves the body via the a lungs when we breath out and via the skin when we sweat to cool is down, sand excess water is lost via the kidneys in the urine
The ion content in the body-ions are lost via the skin when we sweat and excess ions are lost via the kidney in the urine
Temperature-to maintain the temperature at which enzymes work best
Blood sugar levels-to provide the cells with a constant supply of energy
What is the definition of hormones?
Hormones are chemical messages which travel to the blood to activate target cells
What hormones can be used to reduce fertility?
Oestrogen can be used to prevent the release of an egg-so it can be used as a method of contraception. If oestrogen is taken every day to keep the the level high, it inhabits the production of FSH, after a while the egg development and production stops
Progesterone, it stimulates the production of thick cervical mucus which prevents any perm getting through and reaching the egg
The pill is used for oral contraceptive, it contains high levels of of oestrogen and progesterone
Progesterone-only pill, with fewer side effects that the pill (but isn’t as effective)
Pros and cons of the pill
Pros: it is over 99% effective at prenting pregnanc
It reduces the risk of getting some types of cancer
Cons: it isn’t 100% effective, there’s still a very slight chance of getting pregnant
It causes side effect like headaches, nausea, irregular menstrual bleeding and fluid retention
It doesn’t protect against STDs
What can be used to increase fertility?
Some women have levels of FSH that are too low to cause their eggs to mature. This means that no eggs are released and the women can’t get pregnant. The hormones FSH and LH can be injected by these women to stimulate egg release in their ovaries
IVF
What does IVF consist of?
IVF involves collecting eggs from the women’s ovaries and fertilising them in a lab using the man’s sperm. These are then grown jet embryos.
Once the embryos are tiny balls of cells, one or two of them are transferred to the woman’s uterus to improve the chance of pregnancy
FSH and LH are given before egg collection to stimulate egg production (so more eggs are collected)
Pros and cons of injecting FSH and LH hormones to increase fertility
Pros: it helps a lot of women to get pregnant when previously they could’t
Cons: it doesn’t always work - some women may have to do it many time, which can be expensive
Too many eggs could be stimulates, resulting in unexpected multiple pregnancy (twin, triples ect)
Pros and cons of IVF
Pros: fertility treatment can give an infertile couple a child
Cons: some women have a strong reaction to the hormones
There have been some reports of an increase risk of cancer (other reports say there is no such risk)
Multiple birth can happen if more than one embryo grows into a baby, these are risky for the mother and babies (there is a higher risk of miscarriage, stillbirth)
