Section 7 - Animal coordination, control and homeostasis - Hormones, adrenaline and thyroxine Flashcards
What are hormones?
Chemical messengers sent in the blood
Name of 6 endocrine glands?
Pituitary gland, thyroid gland, adrenal glands, ovaries, testes and pancreas
What do the testes produce and what does the hormone do?
Produces testosterone which controls puberty and sperm production in males
What does the thyroid gland produce and what does the hormone do?
Produces thyroxine, which is involved in regulating things like rate of metabolism, heart rate and temperature
What does the pancreas produce and what does the hormone do?
Produces insulin, which is used to regulate blood glucose level
What does adrenal gland produce and what does the hormone do?
Produces adrenaline, which is used to prepare body for a ‘fight or flight’ response by activating processes that increase supply of O2 and glucose to cells
Differences between neurones and hormones?
Neurones: very fast action, act for a very short time, act on a very precise area
Hormones: slower action, act for a long time, act in a more general way
How does adrenaline cause increased respiration?
Adrenaline binds to specific receptors in heart, causing muscle to contract more frequently and with more force, so heart rate and blood pressure increase, increasing blood flow to muscles so cells receive more O2 and glucose for increased respiration
How can your body control levels of hormones in blood using negative feedback systems?
When body detects that level of a substance has gone above or below normal level, it triggers a response to bring level back to normal again
What is metabolic rate?
Speed at which chemical reactions in body occur
What does TRH stimulate to release what?
TRH stimulates pituitary gland to release TSH
What does TSH stimulate to release what?
TSH stimulates thyroid gland to release thyroxine
How does blood thyroxine level rise back to normal when the blood thyroxine level is lower than normal?
Hypothalamus stimulated to release TRH, which stimulates pituitary gland to release TSH.
TSH stimulates thyroid gland to release thyroxine so blood thyroxine level normal
How does blood thyroxine level go fall to normal when blood thyroxine level becomes higher than normal?
Release of TRH from hypothalamus is inhibited, which reduces production of TSH so blood thyroxine level falls
