Action of Drugs on Synapses

Question 1

Define drugs

Answer 1

Drugs are defined as substances causing a sensation of evasion and euphoria; but an
overdose leads to physiological troubles that may lead to death.

Question 2

On what ways do drugs act on?

Answer 2

1. They may inhibit exocytosis.
2. They may facilitate exocytosis.
3. They may occupy the receptors and prevent the fixation of
   neurotransmitters.
4. They may facilitate the fixation of neurotransmitters on the receptors.
5. They may affect the enzyme that degrades the neurotransmitters.

Question 3

Curare

Answer 3

Curare: it is a muscle relaxant that has the same configuration as
acetylcholine. It occupies the same receptors and prevents the fixation of
acetylcholine thus leading to muscle relaxation. Thus, curare and
acetylcholine are antagonistic substances.

Question 4

Cocaine

Answer 4

Cocaine: it blocks the recapture of dopamine by presynaptic neuron.
Dopamine remains on the receptors for longer time. Since dopamine is a
neurotransmitter for pleasure feeling, then cocaine leads to longer
pleasure feeling. Thus, curare and dopamine are agonistic substances.

Question 5

Amphetamines

Answer 5

Amphetamines: such as extasy(ecstasy) drugs that stop appetite since
they cause the release of dopamine from storage vesicles even in the
absence of nervous impulse.

Question 6

Benzodiazepines

Answer 6

Benzodiazepines: anti-anxiety drugs such as valium, activates the fixation
of GABA on its receptors. (GABA is an inhibitory neurotransmitter).

Question 7

Define antagonistic

Answer 7

When 2 substances have opposite function (one inhibits or reduces the
function of the second) then the two substances are antagonistic.

Question 8

Define agonistic

Answer 8

When one activates or increases the function of the other, then they are
agonistic.

Question 9

Endogenous

Answer 9

Any substance that is natural and produced by the body is called
endogenous such as acetylcholine, dopamine…….

Question 10

Exogenous

Answer 10

Any substance prepared artificially is called exogenous such as curare,
cocaine…..