3. Neurotransmission

Question 1

Name 3 inhibitory neurotransmitters

Answer 1

Acetylcholine, Dopamine, GABA

Question 2

Name 2 excitatory neurotransmitters

Answer 2

Dopamine, glutamine

Question 3

Give the mechanism of action at an excitatory synapse

Answer 3

1. Neurotransmitter depolarises the postsynaptic membrane
2. Binding of the neurotransmitter opens up ligand-gated Na+ channels
3. Increased sodium decreases the membrane potential
4. If depolarisation of postsynaptic membrane reaches a threshold, the action potential is generated in the postsynaptic cell

Question 4

What is a graded potential?

Answer 4

Changes in a membrane potential that don’t reach the threshold
Die out over short distances but can be integrated to generate an action potential over longer distances

Question 5

Describe the mechanism of action of an action potential

Answer 5

1. Depolarisation reaches the voltage threshold of -50
2. Voltage gated Na+ channels open in that portion of the membrane
3. More Na+ channels open: wave of depolarisation through axon

Question 6

What is the refractory period?

Answer 6

Time when further stimulus will not trigger a further action potential

Question 7

Why does the refractory period occur?

Answer 7

K+ channels open longer than necessary and cell has to repolarise before it can conduct again

Question 8

What is the mechanism of action at an inhibitory synapse?

Answer 8

1. Neurotransmitter hyperpolarises the postsynaptic membrane
2. Binding of NT to the postsynaptic neuron opens ligand gated Cl- channel
3. Influx of Cl- increases the membrane potential

Question 9

What is multiple sclerosis caused by?

Answer 9

Plaques of demyelination in the brain and spinal cord