Synapses

Question 1

Describe the process

Answer 1

Action potential arrives, calcium channels open
Membrane depolarised calcium ions move into the neurone
Cause synaptic vesicles containging neurotransmitters to fuse with presynaptic membrane
Neurotransmitter is released into synaptic cleft
Neurotransmitter binds with receptors on postsynaptic membrane
sodium channels open and na + flows through
Depolarised - action potential

Question 2

Describe excitatory synapses

Answer 2

Single excitatory synapse doesn’t depolarise the post synaptic membrane enough to produce an actinoal potential at the next neurone
Spatial and temporal summation

Question 3

Describe spatial summation

Answer 3

Impulses from many synapses

Number of sensory cells stimulated

Question 4

Describe temporal summation

Answer 4

several impulses arrive at a synapse having travelled along 1 neurone
Over a period of time

Question 5

Describe inhibitory synapses

Answer 5

Have cl- channels
make it less likely an action potential will occur at post synaptic membrane
neurotransmitter cause cl- channel and K+ channel to open hyperpolarised membrane

Question 6

Describe acetylcholine

Answer 6

Enzyme acetylcholinesterase breaks it down so it cannot bind to receptors
Post synaptic membrane