Synpases

Question 1

Draw a structure of a synapse

Answer 1

Should include:-
Presynaptic neurone 
Post synaptic neurone 
Synaptic cleft 
Neurotransmitter receptor molecule
Sodium ion channels 
Voltage gated calcium ions 
Vesicles containing neurotransmitter 
Mitochondria

Question 2

Describe mechanism of synaptic transmission

Long explanation

Answer 2

1. action potential arrives at the Presynaptic membrane and opens a voltage gated calcium ion channels
2. Calcium ions diffuse into presynaptic knob
3. Calcium ions cause vesicles of neurotransmitter to fuse with the presynaptic membrane
4. Releasing neurotransmitter substance into the synaptic cleft
5. The neurotransmitter diffuses across the synaptic cleft
6. Neurotransmitter substance binds to specific receptors on post synaptic membrane
7. Causing ligand gated sodium ions channels to open
8. Na ions diffuse into the postsynaptic cell
9. Making the membrane less negative
10. If the excitatory postsynaptic potential is at or above the threshold it causes an action potential in the post synaptic cell
11. After the neurotransmitter has acted on the post synaptic membrane it is broken down by an enzyme
12. The components diffuse into the presynaptic cell to be turned back into neurotransmitter

Question 3

What are the two main neurotransmitters

Answer 3

Acetylcholine is the neurotransmitter in CHOLINERGIC synapses in the parasympathetic part of the autonomic Nervous system and neuromuscular junctions
Noradrenaline is the neurotransmitter in most of the sympathetic part of the autonomic Nervous system

Question 4

Describe the sequence of events in temporal summation

Answer 4

1. Impulses arrive at presynaptic membrane one after the other
2. Each impulse causes the release of neurotransmitter
3. Enough neurotransmitter is now released to get the EPSP above the threshold of the synaptic neurone
4. An action potential develops in the post synaptic neurone