9- effects of drugs on the nervous system

Question 1

nicotine affect

Answer 1

• Mimicking effects of acetylcholine.
• Excitatory.
• At low doses it has a stimulating effect, but at high doses it blocks receptors and can kill.

Question 2

nicotine mode of action

Answer 2

• It binds to acetylcholine receptor sites. This causes more
acetylcholine to be produced, and a feeling of greater alertness as synapses are excited.
• It causes the release of dopamine.
High dopamine and acetylcholine levels stimulate the release of endorphins in the brain, which produce a feeling of relaxation and euphoria.

Question 3

lidocaine affect

Answer 3

• Blocking voltage gated Na+ ion channels.
• Inhibitory.
• Used as a local anaesthetic.
• Prevents arrhythmia at low doses.

Question 4

lidocaine mode of action

Answer 4

Blocks voltage-gated Na+ ion channels from opening. The postsynaptic membrane is not able to depolarise. This prevents the production of an action potential in sensory neurons, thus no action potentials can travel to the CNS to record pain.

Question 5

cobra venom effect

Answer 5

• Blocking acetylcholine receptors.
• Inhibitory.
• Toxic and often fatal in snake bites.
• At low doses it can relax the muscles of the trachea and bronchi in asthma attacks.

Question 6

cobra venom mode of action

Answer 6

• It binds to acetylcholine receptors sites, and blocks them.
• Na+ ion channels remain permanently open. After an initial action potential, no further ones can be generated.
• Muscles aren’t stimulated to contract, thus causing paralysis.
• When the toxin reaches the muscles involved in breathing, it causes death.