Drugs

Question 1

Excitatory drugs

Answer 1

Increases number of action potentials in post-synaptic neurone (organophosphates)

Question 2

Inhibitory drug

Answer 2

Decreases number of action potentials in the post-synaptic neurone (botox prevents release of a.ch. from vesicles)

Question 3

Agonists and Antagonists

Answer 3

Agonist- fit into receptor and stimulates it like neurotransmitter (nicotine to a.ch. receptors)
Antagonist- fits into receptorbut blocks it so neurotransmitter can’t bind (curare arrow poison)

Question 4

Drugs increasing activity

Answer 4

• Mimic action of neurotransmitters and bind to receptors and stimulate it
• Prevent/ inhibit breakdown of neurotransmitters
• Stimulate release of neurotransmitters
• Block uptake of neurotransmitters back into pre-synaptic knob
• Reduce threshold for excitation of post-synaptic membranes

Question 5

Drugs decreasing activity

Answer 5

• Block receptors on post-synaptic membrane to prevent neurotransmitters binding (beta-blockers)
• Prevent exocytosis and release of neurotransmitter
• Blocking of Ca2+ ion uptake
• Changes shape of neurotransmitter
• Prevents recycling / resynthesis of neurotransmitters
• Prevent synthesis of neurotransmitter
• Changes shape of sodium ion channels in post-synaptic membrane

Question 6

Organophosphates

Answer 6

• A.ch. normally hydrolysed or broken down by acetylcholinesterase
• Organophosphates inhibit a.ch.ase so prevent breakdown of a.ch.
• A.ch remains bound longer to receptors on post-synaptic membrane
• Action potentials continue to be generated
• Uncontrolled contractions of muscles like diaphragm = breathing difficulty
• Sustained contraction of muscles = tremors

Question 7

Cocaine

Answer 7

• Blocks dopamine transporter
• Does not allow flow of dopamine back into pre-synaptic neurone
• Dopamine remains in synaptic cleft for longer
• Remains bound to receptors on post-synaptic for longer
• Intensifies and prolongs stimulation of post-synaptic neurone

Question 8

Psychoactive drugs

Answer 8

Act primarily on CNS by affecting neurotransmitters or receptors = affects firing of neurones
Alter brain function = change in perception, mood, consciousness and behaviour
Cocaine, heroin, cannabis, amphetamines, ecstasy