Homeostasis and reponse Flashcards
cells and receptors
detect stimuli (changes in the environment)
coordination centres
receive information from receptors e.g brain
effectors
bring about responses to restore optimum levels e.g muscles
receptor
detect stimuli
sensory neurone
long axon carries impulses from receptor to spinal cord
synapse
gap where neurones meet. Chemical message using neurotransmitter
relay neurone
allows impulses to travel between sensory and motor neurones in the spinal cord
motor neurone
long axon carries impulses impulse from receptor to effector
effector
muscle or gland that carries out response
what does CNS stand for
central nervous system
brain and spinal cord are part if the
CNS
what does the CNS do?
coordinates the response of effectors : muscles contracting or glands secreting hormones
the order
stimulis receptor coordinatior effector response
example of a reaction
light switch on cells in retina CNS muscles connected to iris pupils get smaller
what does the CNS enable humans to do
react to their surroundings and to co-ordinate their behaviour
Homeostasis
the regulation of internal conditions of a cell or organism to maintain optimum conditions to function
what are the 3 controls in the human body
blood glucose concentration
body temp
water levels
Homeostasis maintains…
optimal conditions for enzyme conditions and all cell function
What is the endocrine system
composed of glands which secrete chemicals called hormones directly into the bloodstream
how does the endocrine system work
the blood carries hormone to target organ where it produces an effect
how does the endocrine system compare to the CNS
effects are slower but act for longer
What is the pituitary gland
‘master gland’
it secrets several hormones into the blood
how does the pituitary gland work
stimulates other glands to produce hormones to bring about effects
what does the pancreas monitor and control levels of
blood glucose concentration
what happens when blood glucose concentrations are too high
pancreas produces the hormone insulin
glucose moves from the blood into the cells
in liver and muscles cells excess glucose is converted to glycogen for storage
what happens when blood glucose concentration is too low (HT only)
pancreas produces the hormone glucagon that causes glycogen to be converted into glucose and released into the blood
type 1 diabetes
pancreas fails to produce sufficient insult leading to uncontrolled blood glucose levels normal treated by insulin injections
type 2 diabetes
obesity is a risk factor
body cells no longer respond to insulin
common treatments involve changing diet by increasing excersie
negative feedback (HT only) of Adrenaline
produced in adrenaline glands increases breathing/heart rate blood flows to muscles conversion glycogen ton glucose prepares body for fight or flight
negative feedback (HT only) of Thyroxine
produced in the thyroid gland
stimulates the basal metabolic rate
important for growth and development
