Homeostasis (coordination and control) * Flashcards
What are hormones? (3 points)
chemical messengers that move in the blood
they are made in specific cells which secrete them into the blood
the blood transports them around the body until they reach the target cell which responds in some way
What are the two main methods of communication?
endocrine (hormones) system
nervous (electrical impulses) system
Name the 6 glands in the endocrine system
pituitary (master gland)
thyroid
adrenal
pancreas
ovary
testes
Which hormones does the pituitary gland release?
FSH
LH
growth hormone
What hormone does the thyroid release?
thyroxine
What hormone does the adrenal gland release?
adrenaline
Which hormones does the pancreas release?
insulin
glucagon
What hormone does the testes release?
testosterone
Which hormones does the ovary release?
oestrogen
progesterone
What does thyroxine control?
the metabolic rate
How does thyroxine control the metabolic rate? (an example of negative feedback)
- low levels of thyroxine stimulate the production of TRH in the hypothalamus
- this causes the release of TSH from the pituitary gland
- TSH acts on the thyroid to produce thyroxine
- when thyroxine levels are normal thyroxine inhibits the release of TRH and the production of TSH
What is negative feedback?
when the levels of certain substances in the body go above or below normal and the body triggers responses to bring these levels back to normal
What does adrenaline do?
prepares the body for ‘fight or flight’/states of emergency
How does adrenaline prepare the body for fight or flight?
- binds to receptors on heart and increases heart rate
- increases blood pressure
- increases blood flow to muscles so more oxygen and glucose to muscles so more respiration
- raised blood sugar levels by stimulating the liver to change glycogen to glucose
