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define ‘stimulus’
a detectable change in the environment
what is a receptor and what does it do?
a structure which detects stimulus
what is a coordinator and what does it do?
organ which helps organisms detect stimuli
give two examples of coordinators
brain,spinal cord
what is an effector and what does it do?
part of body which brings about response to stimuli
give two examples of effectors
muscles,glands
how do organisms detect and respond to stimuli?
stimulus receptor coordinator effector response
how does the nervous system work?
nerve impulses transmitted through nerve cells
in the nervous system, responses are…
short-lived
nerve impulses travel…and have an…
fast,instant effect
how does the endocrine system work?
hormones transmitted through bloodstream
hormones travel…and generally take…
more slowly,longer to act
in the endocrine system, responses are…
usually longer-lasting
the central nervous system(CNS) contains…
relay neurones
how do motor neurones work?
transmit impulses from the CNS to effector
how do sensory neurone work?
transmit impulses from receptor to CNS
why might reaction times differ?
age,fatigue,gender
what is a reflex?
automatic,involuntary response to stimulus,impulses are not started in brain
what is the purpose of reflexes?
protect body from immediate harm
what are synapses?
connections between neurones, neurones do not touch at synapses because there is a gap which neurotransmitter diffuses
what is the purpose of synapses?
ensure impulses flow in one direction,transmitter releases on one side,receptors on another
how do synapses work?
electrical impulses travel to end of first neurone, impulse triggers release of chemical neurotransmitter,neurotransmitter diffuses across gap, binds to receptors on another neurone,new electrical impulse travels down the neurone
what is shown in this diagram?
motor neurone
what is shown in this diagram?
sensory neurone
what is shown in this diagram?
relay neurone
