Topic 7 Flashcards
How do hormones enter the body?
Hormones are chemicals released directly in the blood. They are carried in the blood to other parts of the body, but only affect particular cells in particular organs. Hormones control things in organs and cells that need constant adjustment.
Where are hormones produced?
Hormones are produced in (and secreted) by various glands, called endocrine glands. These glands make up your endocrine system.
What does the pituitary gland do?
The pituitary gland produces many hormones that regulate body conditions. It is sometimes called as the master gland because these hormones act on other glands directing them to release hormones that bring about change.
What does the thyroid gland do?
This produces thyroxine, which is involved in regulating things like the rate of metabolism, heart rate and temperature.
What does the pancreas do?
This produces insulin which is used to regulate the blood glucose level.
What does the testes do?
Produces testosterone, which controls puberty and sperm production in males
What does the ovaries do?
produces estrogen which is involved in the menstrual cycle.
How does the adrenal gland work?
1) Adrenaline binds to specific receptor in the heart. Causes heart muscle to contract more frequently, so hear rate and blood pressure increases.
2) Increases blood flow to muscles, so the cells receive more oxygen and glucose for increased respiration.
3) Adrenaline also binds to receptors in the liver. This causes the liver to break down its glycogen stores to release glucose.
4) This increase the blood glucose level, so there’s more glucose in the blood to be transported to the cells.
What happens when the brain detects stressful situations?
It sends nervous impulses to the adrenal glands which response by secreting adrenaline. This gets the body ready for action.
What is thyroxine?
1)Thyroxine is a hormone released by the thyroid gland.
Why is thyroxine important?
It regulates metabolic rate- the speed at which chemical reactions in the body occur.
What does the negative feedback do?
A negative feedback system keeps the amount of thyroxine in the blood at the right level
Negative feedback process-
- When the blood thyroxine level is lower than normal, the hypothalamus (a structure in the brain) is stimulated to release thyrotropin releasing hormone (TRH).
- TRH stimulates the pituitary glands to release thyroid stimulating hormone (TSH).
- TSH stimulates the thyroid gland to release thyroxine, so the blood thyroxine level rises back towards normal.
- When the blood thyroxine level becomes higher than normal, the release of TRH from the hypothalamus is inhibited, which reduces the production of TSH, so the blood thyroxine level falls.
