Biology: Endocrine System Flashcards
What do endocrine glands do ?
secrete hormones into the bloodstream, respond more slowly than the nervous system but the effects are longer lasting
What is released from the pineal gland?
melatonin
What is released from the pituitary gland?
growth hormone
oxytocin in childbirth
What is released from the thyroid gland?
thryoxine to increase metabolic rate
What does the parathyroid gland do ?
it increases blood calcium
What does the thymus gland do ?
thymosin for t-lymphocytes in immunity
What does the pancreas do ?
releases insulin to reduce blood glucose levels and glucagon to increase blood sugar levels
What does the adrenal gland do ?
releases steroid hormones in response to stress
What do the ovaries and testes release?
oestrogen and progesterone
testosterone
What does the kidney do?
it isn’t an endocrine gland but it releases the hormones EPO to increase red blood cell production
What is negative feedback ?
resists change
inhibits any deviation from the norm
detection of a change inhibits the change
e.g. food intake = rise in blood glucose above norm- detected by receptors in pancreas, therefore insulin is secreted from beta cells to the target organ and liver stores glucose as glycogen so blood glucose levels drops so insulin stops being released
What happens when blood glucose levels are too low?
the pancreas detects this and secretes glucagon stimulating the release of glucose by the liver
What do most homeostatic controls use?
use negative feedback mechanisms to oppose any change
What is positive feedback ?
magnifies change
promotes any deviation from the norm
detection of a change stimulates the change
What is an example of positive feedback ?
start of menstrual cycle
rise in pituitary FSH causes ovaries to produce more oestrogen leading to a rise in pituitary LH and ovaries produce more oestrogen causing LH surge
