13.5 Effects of Drugs on Synapses

Question 1

Drugs cause their effects by acting on synapses. What result does this have, on the nervous system?

Answer 1

The nervous sytem is stimulated or inhibited

Question 2

What do stimulatory drugs do?

Answer 2

Create more action potentials in postsynaptic membranes, resulting in an enhanced response.

Question 3

How do stimulatory drugs work?

Answer 3

1. Mimicking shape of neurotransmitter - nicotine is the same shape as ACE. Therefore, nicotine can bind to ACE receptors on the postsynaptic membrane and trigger APs
2. Stimulate release of more NT, e.g. amphetamine#
3. Inhibit enzymes responsible for breaking down NTs. e.g. nerve gases stop ACE being broken down, resulting in loss of muscle control

Question 4

What do inhibitory drugs do?

Answer 4

Create fewer APs in postsynaptic neruon, resulting in a reduced response.

Question 5

How do inhibitory drugs work?

Answer 5

1. Block receptors - this means NTs can no longer bind and activate the receptor. e.g. curare block ACE receptors at neuromuscular junctions. The muscle cells can’t be stimulated, so the person often suffers from paralysis
2. Bind to specific receptors on post synaptic membrane of some neurones and change the shape of the receptor, so binding of NT increases. This increases activity. e.g. alcohol binding to GABA receptors