Question

which drug effects dopamine levels in the synaptic cleft?

a. cocaine

b. caffeine

c. nicotine

d. methamphetamine

e. all of these

value: 10

what is a chronic effect of nicotine?

a. decrease in neurons that produce dopamine

b. decrease the number of dopamine receptors

c. low levels of dopamine

d. fusion of the synaptic cleft

value: 10

restinal membrane potential the charge on a neuron memebrane is ______.

a. positive on the inside and negative on the outside

b. positive on both sides

c. negative on both sides

d. positive on the outside and negative on the inside

e. positive on the outside and neutral on the inside

Explanation:

First Question:

Cocaine, methamphetamine affect dopamine reuptake or release in the synaptic cleft. Caffeine and nicotine have different mechanisms (caffeine is adenosine antagonist, nicotine is nicotinic receptor agonist) but actually, cocaine, methamphetamine, and also nicotine/caffeine have complex effects, but the option "e. All of these" is incorrect? Wait, no—wait, cocaine blocks dopamine reuptake, methamphetamine increases dopamine release and blocks reuptake, nicotine can affect dopamine systems indirectly, caffeine may have some effects too? Wait, no, the correct answer is e? Wait, no, let's recheck. Cocaine (a) blocks dopamine reuptake, methamphetamine (d) increases dopamine release and blocks reuptake. Nicotine (c) activates nicotinic receptors which can lead to dopamine release. Caffeine (b) is adenosine antagonist, but does it affect dopamine? Some studies say caffeine can modulate dopamine. But maybe the intended answer is e? Wait, no, maybe the question is about drugs that directly affect dopamine levels in synaptic cleft. Cocaine (a) blocks reuptake, so dopamine stays. Methamphetamine (d) causes release. Nicotine (c) can trigger dopamine release. Caffeine (b) may have indirect effects. But the option e is "All of these". So the correct answer is e.

Chronic nicotine use leads to a decrease in the number of dopamine receptors (downregulation) as the brain tries to adapt to increased dopamine from nicotine's effects. Option a: neurons producing dopamine don't decrease. Option c: low dopamine? No, chronic nicotine can lead to receptor downregulation, so when not using, dopamine signaling is reduced, but the chronic effect is receptor number decrease. Option d: synaptic cleft doesn't fuse. So correct is b.

Resting membrane potential of a neuron: the inside is negative (due to more K+ inside, Na+ outside, and anions) and outside is positive (more Na+). So the charge is positive on the outside and negative on the inside. So option d.

Answer:

e. All of these

Second Question: