transmission of nerve impulses across a synapse

Question 1

stage 1

Answer 1

nerve impulse arrives at synaptic knob causing calcium channels on pre-synaptic membrane to open

Question 2

stage 2

Answer 2

calcium ions diffuse into the synaptic knob

Question 3

stage 3

Answer 3

calcium ions cause vesicles containing acetylcholine to migrate towards the pre-synaptic membrane

Question 4

stage 4

Answer 4

vesicles release acetylcholine fuse with the pre-synaptic membrane

Question 5

stage 5

Answer 5

vesicles release acetylcholine into the synaptic cleft by exocytosis

Question 6

stage 6

Answer 6

acetylcholine molecules diffuse across the synaptic cleft

Question 7

stage 7

Answer 7

acetylcholine molecules bind to receptor sites on the post synaptic membrane causing sodium channels to open

Question 8

stage 8

Answer 8

sodium ions diffuse from the synaptic cleft into the post synaptic neurone

Question 9

stage 9

Answer 9

the post synaptic membrane depolarises and a nerve impulse is set up

Question 10

stage 10

Answer 10

acetylcholinesterase is released

Question 11

stage 11

Answer 11

this enzyme hydrolyses acetylcholine so sodium channels on the post synaptic membrane close and the impulse stops

Question 12

stage 12

Answer 12

this allows the enzyme to repolarise ready for the next impulse