Neural Communication Flashcards
(51 cards)
what happens at the synapse
- electrical impulse arrives at presynaptic neurone
- neurotransmitters are found inside vesicles
- these are released and diffuse across synaptic cleft
- they attach to the receptors on postsynaptic neurone
- this generates an impulse
which receptors detect touch/pressure
mechanoreceptors
which receptors detect chemical change
chemoreceptors
which receptors detect a change in temperature
thermoreceptors
which receptors detect a change in light
photoreceptors
what’s the main example of a mechanoreceptors
percinian corpuscle
what’s a generator potential
receptor converting stimuli into nervous impulse
what’s a transducer
transfers mechanical energy into electrical energy
what’s a transducer
transfers mechanical energy into electrical energy
What happens ween the percinian corpasule is stimulated
- pressure causes lamellae to stretch and deform
- stretch mediated Na ion channels open
- Na ions diffuse into neurones
- greater the stimulus, the more open channels
- depolarisation of neurons is called generator potential
what’s the resting potential
difference in charge between inside and outside the axon
what’s the resting potential in humans
-70mV
explain what happens when there’s an incoming action potential
- AP causes depolarisation causing Ca+ channels to open
- Ca+ flood into synaptic knob by facilitated diffusion, down an electrochemical gradient
- Ca+ causes synaptic vesicles to fuse with presynaptic membrane
- releases acetylcholine into the cleft
- this is then realeased into the synaptic cleft
- neurotransmitter binds to receptors on Na+ channels - causing a confirmational change in the channels, opening the channels
- acetylcholinesterase breaks up the acetylcholine into acetyl and choline (Na+ channels wouldn’t close if not broken down)
- products diffuse back across cleft into presynaptic neurone
- ATP from mitochondria is used for recycling acetylcholine - more AC can be made at the SER
what’s the all or nothing principle
action potential only happens if stimulus reaches a threshold value (-55mV)
what’s the refractory period
time after depolaristation where no new action potential can start, no stimulus will trigger an AP
why is the refractory period important
- gives more time to restore voltage
- Na+ channels can’t be opened as it’s depolarised
what’s the salatory conduction
the AP jumping between schwann cells as it only occurs at the node of Ranvier
what’s summation
low frequency action potential often releases insufficient neurotransmitters to exceed threshold
spatial summation is…
number of different presynaptic neurones share same synaptic cleft
together they can release enough NT to creat an AP
temporal summation is…
a single presynaptic neurone releases NT many times over a short period of time
what does GABA do
it binds to receptors of chloride ion channels of postsynaptic membrane
if open chloride ions flood into postsynaptic neurone
this hyperpolarises the neurone
makes it harder to reach threshold
what is GABA
an inhibatory neurotransmitter
what are the characteristics of the autonomic NS
- subcouncious control
- automatic
- impulses sent to glands and smooth cardiac muscles
what are the characteristics of the somatic NS
- concious control
- voluentary
- impulses sent to body’s muscles
