Lecture 13: Drug Actions, Neurotransmitters, and Action Potentials

Vocabulary flashcards covering drug mechanisms of action (agonists and antagonists), chronic drug use phenomena, drug classifications, and the phases of neuronal action potentials.

Agonist

A substance that enhances a neurotransmitter system by increasing synthesis, increasing release, mimicking the neurotransmitter, or blocking degradation.

Antagonist

A substance that diminishes a neurotransmitter system by blocking release, blocking the receptor, or decreasing neurotransmitter effects.

Black widow spider venom

An agonist that promotes acetylcholine release, causing greater omega body formation, potentially leading to seizures or suffocation.

Nicotine

An agonist that stimulates receptors by tricking the acetylcholine receptor into responding as though acetylcholine has bonded to it, causing muscle contractions.

Physostigmine and organophosphates

Agonist substances that block inactivation of acetylcholine, which activates acetylcholine receptors and causes dry mouth.

Botulin toxin

An antagonist that blocks the release of acetylcholine, leading to a lack of muscle restriction and suffocation.

Curare

A typical antagonist derived from leafy plants often found in South America that blocks acetylcholine receptors, potentially leading to suffocation.

Tolerance

The reduced impact or effect of a drug due to taking it over time, or the requirement to take more of the drug to achieve the same impact.

Cross-tolerance

A condition occurring when tolerance to one drug produces tolerance to a second drug because both drugs share a similar mechanism of action.

Sensitization

The increased impact or effect of a drug resulting from taking the drug over time.

Sedatives

A class of drugs that increases IPSPs and typically works via GABA receptors (including benzodiazepines, barbiturates, alcohol, angel dust, GHB, and ketamine).

Antipsychotics

Drugs that typically work as dopaminergic antagonists at dopamine receptors to decrease dopamine activity (such as Haldol, haloperidol, and clozapine).

Tardive dyskinesia

A movement disorder condition that must be monitored when administering antipsychotic drugs.

MAO-I

A type of antidepressant medication that functions by blocking neurotransmitter degradation.

SSRIs

A class of antidepressant medications that works by blocking serotonin reuptake.

Naloxone

A non-competitive antagonist that blocks opioid effects.

Stimulant-Induced Psychosis

Psychotic symptoms triggered by very high dopamine activity resulting from high stimulant use.

Resting Membrane Potential

The electrical potential across a neuronal membrane of approximately $-70\,\text{mV}$, produced by differential concentrations of sodium ions ($Na^+$) more concentrated outside and potassium ions ($K^+$) more concentrated inside.

Repolarization

The stage of the action potential produced when voltage-dependent potassium channels open and potassium ions ($K^+$) leave the neuron along their electrochemical concentration gradient.

Hyperpolarization (overshoot)

The phase during an action potential produced when voltage-dependent potassium channels close too slowly after repolarization.

Sodium-potassium pump

The cellular mechanism that reestablishes the resting membrane potential following the hyperpolarization phase of an action potential.