motor function

Question 1

contact ratio for NMJ

Answer 1

1:1

Question 2

what is the presynaptic terminal also known as

Answer 2

bouton

Question 3

how can membrane potential of post-synaptic neurone be altered (2 ways) in CNS

Answer 3

made less negative (closer to firing threshold) - excitatory post-synaptic potential (EPSP); made more negative (further away from firing threshold) - inhibitory post-synaptic potential (IPSP)

Question 4

what is the name of graded effects in CNS

Answer 4

summation of excitatory and inhibitory effects

Question 5

what does degree of summation in CNS determine

Answer 5

how readily a neurone can reach threshold to produce an action potential

Question 6

define NMJ

Answer 6

specialised synapse between motor neurone and motor end plate (muscle fibre cell membrane); always excitatory

Question 7

how is the NMJ activated

Answer 7

action potential arrives at terminal bouton (saltatory conduction down nodes of Ranveir of efferent neurone) -> Ca2+ influx -> ACh release -> ACh binds to receptors on motor end plate -> ion channels open -> Na+ influx causes action potential in muscle fibre

Question 8

why do miniature end-plate potentials (mEPP) exist at rest

Answer 8

individual vesicles release ACh at very low rate