synpases

Question 1

how is the action potentail mainatained

Answer 1

-70 mv- electrical difference across membrane when neurone is at rest
Outside is more pos. than inside- membrane becomes permeable to na + k pump- protein+ atp- active transport
3na+ in – 1k+ out – 1 loss of charge
Membrane more to permeable to k+ as some k+ channels are permanently open + there are more of them- allows k+ to move out faster than Na+ move in maintaining -70mv

Question 2

action potential process

Answer 2

-Outside of neurone is more pos. charge than inside
-depolarisation-exceeds threshold of -55mv- Na+ channels open – Na+ flood in neuron reaching +30mv
Repolarization- sodium ion channels close-k+ channels open- negative
Hyperpolarisation/refractory period– 80mv -overshoots decrease in voltage –

Question 3

mexican wave throey

Answer 3

action potenials happen in one drection at each node of ranvier travelling along axon

Question 4

all or nothin gprinciple

Answer 4

if a.p. doesnt exceed threshold- no a.p.
all have same volatage but may have different frequecnices if large
only responds to large stumuli

Question 5

why is the refeactory period important

Answer 5

discrete impulses+one direction-limits amount of a.p. so you dont get overwhelmed by small changes

Question 6

factors affecting conduction

Answer 6

axon diameter-less leakage of ions
temperature
saltatory conduction-diffuses node to node doesnt travel along whole of axon
insulative sheath-prevents ions diffucing out of axon

Question 7

process in cholinergic synapse

Answer 7

depolarisation wave reaches presynaptic knob open ca+
vesicle carrying acetylcholine fuses wit presynaptic membrane
releases acetyl choline diffuses down concentration gradient across the cleft binding to receptors on post synaptic knob membrane
opens Na+ channel causing depolarisation
acetyl choline esterase degrades ach into acetyl and choline -
the reestablishes resting potential

Question 8

neuromuscular joints

Answer 8

excitatory
neurone to muscle
end of response
acteyl cholin binds to receptor of muscle membrane
opposite of chloinergenic

Question 9

inhibitory synapse

Answer 9

releases chloride ions to postsynaptic membrane -open channels
decreases neuron potentail to -80mv-no a.p.-hyperpolarisatoin after to maintian normal