Drugs Fit Like Keys into Molecular Locks

Question 1

Ligand

Answer 1

A substance that binds to receptor molecules, such as a neurotransmitter or drug that binds postsynaptic receptors.

Question 2

Figure 4.5

The Agonistic and Antagonistic Actions of Drugs

Answer 2

Question 3

Agonist

Answer 3

A molecule, usually a drug, that binds a receptor molecule and initiates a response like that of another molecule, ususally a neurotransmitter.

Question 4

Antagonist

Answer 4

A molecule, ususally a drug, that interferes with or prevents the action of a neurotransmitter.

Question 5

Binding Affinity or Affinity

Answer 5

The propensity of molecules of a drug (or other ligand) to bind to receptors.

Question 6

Efficacy or Intrinsic Activity

Answer 6

The extent to which a drug activates a response when it binds to a receptor.

Question 7

Dose-Response Curve (DRC)

Answer 7

A formal graph of a drug’s effects (on the y-axis) versus the dose given (on the x-axis).

Question 8

Figure 4.6

The Dose-Response Curve

Answer 8

Question 9

Bioavailable

Answer 9

Referring to a substance, usually a drug, that is present in the body in a form that is able to interact with physiological mechanisms.

Question 10

Biotransformation

Answer 10

The process in which enzymes convert a drug into a metabolite that is itself active, possibly in ways that are substantially different from the actions of the original substance.

Question 11

Blood-Brain Barrier

Answer 11

The mechanisms that make the movement of substances from blood vessels into brain cells more difficult than exchanges in other body organs, thus affording the brain greater protection from exposure to some substances found in the blood.

Question 12

Drug Tolerance

Answer 12

Also called simply tolereance. A condition in which, with repeated exposure to a drug, an individual becomes less responsive to a constant dose.

Question 13

Metabolic Tolerance

Answer 13

The form of drug tolerance that arises when repeated exposure to the drug causes the metabolic machinery of the body to become more efficient at clearing the drug.

Question 14

Functional Tolerance

Answer 14

The form of drug tolerance that arises when repeated exposure to the drug causes receptors to be up-regulated or down-regulated.

Question 15

Down-Regulation

Answer 15

A compensatory decrease in receptor availability at the synapses of a neuron.

Question 16

Up-Regulation

Answer 16

A compensatory increase in receptor availability at the synapses of a neuron.

Question 17

Cross-Tolerance

Answer 17

A condition in which the development of tolerance for one drug causes an individual to develop tolerance for another drug.