1.5.12 medical application

Question 1

mimic neurotransmitter

Answer 1

Drugs with a similar shape to neurotransmitters can mimic their function.
The drug can bind to receptors on the postsynaptic membrane to produce an action potential.
These drugs are called agonists.
E.g. Nicotine can bind to nicotinic cholinergic receptors in the brain to mimic acetylcholine.

Question 2

inhibit enzymes

Answer 2

Drugs can bind to enzymes to prevent the breakdown of a neurotransmitter.
The neurotransmitter would continue to generate an action potential in the postsynaptic membrane.
E.g. Nerve gas inhibits acetylcholinesterase and stops the breakdown of acetylcholine. This causes loss of muscle control.

Question 3

release of neurotransmitter

Answer 3

Drugs can cause presynaptic neurones to release neurotransmitters.
More neurotransmitters will activate more receptors and an action potential is more likely to be created.

Question 4

block calcium ion channels

Answer 4

Drugs can block calcium ion channels in the presynaptic membrane.
Blocking calcium ion channels would prevent the release of neurotransmitters from the presynaptic neurone.
E.g. Alcohol.

Question 5

block receptors

Answer 5

Drugs can block receptors on the postsynaptic membrane.
If the receptors are blocked, neurotransmitters cannot bind and an action potential is not generated in the postsynaptic neurone.
These drugs are called antagonists.
E.g. Curare blocks nicotinic cholinergic receptors causing muscle paralysis.