Neurotransmission & Psychoactive drugs

Question 1

Ionotropic receptors respond by…

Answer 1

…opening opening a pore/channel in them.

Question 2

Metabotropic receptors respond by…

Answer 2

…triggering a cascade of intracellular events.

Question 3

The cascade of events when a metabotropic receptor is activated:

Answer 3

1. Activation of the receptor by a neurotransmitter.
2. Binding and activation of the intracellular G-protein.
3. Release of second messengers.
4. Opening of ion channels by second messengers.

Question 4

What is the function of the allosteric site?

Answer 4

The allosteric sites bind molecules too, like the active site, but they cannot trigger any action on the receptor by themselves. They serve to attenuate or augment the action of the active site.

Question 5

How do competitive antagonists function?

Answer 5

They disable receptors by blocking the active sites.

Question 6

List the major neurotransmitter systems:

Answer 6

• adrenergic
• dopaminergic
• serotoninergic
• cholinergic

Question 7

How does alcohol work in the brain?

Answer 7

It binds to the allosteric sites of GABA receptors, potentiates the action of GABA, thereby increasing its inhibitory effects

Question 8

Eight stages of neurotransmission:

Answer 8

1. action potential
2. opening of Ca++ channels
3. flow of Ca++ ions
4. Ca++ -induced exocytosis of neurotransmitters into the synaptic cleft
5. binding of neurotransmitter to postsynaptic receptors
6. opening of (postsynaptic) ion channels
7. generation of postsynaptic potential

Question 9

Which receptor is faster: ionotropic vs. metabotropic?

Answer 9

Ionotropic receptors are faster, metabotropic receptors open more ion channels.