Hormones Flashcards
What is a hormone?
Chemical molecules released directly into blood, they control things in organs and cells that need constant adjustment
What is the endocrine system?
A group of glands that produce the hormones used in our body
Blood glucose is controlled by what two hormones?
Insulin and glucagon
If the blood glucose level is too high….
Insulin is secreted by the pancreas
Insulin makes the liver turn glucose into glycogen
Therefore there’s less glucose in the blood and the glucose levels fall
If blood glucose levels are too low…
Glucagon is secreted by the pancreas
Glucagon forces liver to break down glucagon into glucose and release it
This means more glucose is in the blood so blood glucose levels rise
With type one diabetes the pancreas produces…
Little or no insulin meaning their blood glucose levels could get to a level that could kill them. Therefore they need insulin injections throughout the day to ensure glucose is removed from their body
With type two diabetes a person becomes….
Resistant to their own insulin (insulin is still produced, their body cells just don’t respond properly to the hormone), this could cause their blood glucose levels to rise very very high.
How can oestrogen be used to reduce fertility?
They can prevent the release of an egg so can be used as contraception. This is because it stops the production of FSH so after a while egg development and production stop
What is the pill?
A contraceptive containing oestrogen and progesterone.
What does FSH do?
Produced in the pituitary gland
Causes egg to mature
Stimulates ovaries to produce oestrogen
What does oestrogen do?
Produced in ovaries
Causes lining of uterus to grow
Stimulates release of LH and inhibits release of FSH
LH
Produced by pituitary gland
Stimulates release of egg
Progesterone
Produced in ovaries
Maintains lining of uterus during second half of cycle, when progesterone levels falls the lining breaks down
What is thyroxine?
It is responsible for regulating the growth and brain development of young animals
Regulates the rate of metabolism, heart rate and temperature
What happens when the concentration of thyroxine is too high in the blood:
It is detected by the pituitary gland meaning less TSH is released - this causes the secretion of thyroxine from the thyroid gland to slow bringing the thyroxine level in the blood to return to normal
What happens if the concentration of thyroxine is too low?
- lack of thyroxine is detected by the pituitary gland
- pituitary gland releases TSH
- TSH stimulates the thyroid gland to release more thyroxine
- this causes the levels to rise
What does adrenaline do?
- prepares body for action when in shock, under stress or threatened in some way
- enlarges air passages of lungs to allow more oxygen and glucose to be delivered to muscles and brain
- dilates pupils
- increases heart rate
Are insulin injections a useful treatment for type 2 diabetes?
No
What is the menstrual cycle?
A monthly cycle which involves the maturation and release of an egg
What happens in stage one of the menstrual cycle?
The uterus lining breaks down for about four days
What happens in stage two of the menstrual cycle?
The uterus lining builds up again from day 4 to day 14, into a thick spongy layer full of blood vessels
What happens in stage 3 of the menstrual cycle?
Ovulation happens - an egg develops and is released from the ovary at day 14
What happens at stage 4 of the menstrual cycle?
The uterus wall is maintained until day 28. 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
How does the contraceptive patch work?
It contains oestrogen and progesterone and is stuck on the skin. Each patch lasts one week
How does the contraceptive implant work?
It is inserted under the skin and continuously releases progesterone which inhibits the release of FSH and LH causing no egg to be released. Implant lasts for 3 years
How does the contraceptive injection work?
It contains progesterone. Each dose lasts 2 to 3 months
What does the fertility drug contain?
FSH and LH because some women’s natural levels of FSH are too low to cause their eggs to mature. This means no eggs are released and the women can’t get pregnant
Pros of the fertility drug?
Helps women get pregnant when it doesn’t always work
Cons of the fertility drug?
- it doesn’t always work - some women may have to do it many times which can be expensive
- too many eggs could be stimulated resulting in unexpected multiple pregnancies (e.g. triplets)
Why are some people against IVF?
- it often results in unused embryos being destroyed (people think this is unethical because each embryo is a potential human life)
- the genetic testing of embryos before implantation raises ethical issues as people think it could lead to the selection of preferred characteristics e.g. eye colour
