Quiz 4: Drug Receptors

The primary location for receptors that recognize drugs and endogenous compounds is: A)on the cell's surface. B)in the cell's cytoplasm. C)on the cell's nuclear membrane. D)on the cell's chromosomes. E)on the ribosomes.

The acetylcholine receptor located on the postsynaptic membrane of the skeletal neuromuscular junction is an example of a membrane receptor that: A)is directly linked to an intracellular enzyme. B)is directly linked to a regulatory G protein. C)functions as an ion channel or pore. D)moves (translocates)to the cell's nucleus when stimulated. E)none of the above

Signals from the surface receptor are transduced to the appropriate response within the cell via intermediate regulatory proteins that are activated by binding guanine nucleotides;hence,they are often termed ______ proteins. A)activating B)binding C)controlling D)nucleotide E)G

Some drugs affect the function of the adenylate cyclase,an enzyme located on the inner surface of the cell membrane.This enzyme is responsible for hydrolyzing adenosine triphosphate (ATP)into _____,which acts as a second messenger that activates other enzymes (i.e. ,protein kinases)throughout the cell. A)adenosine diphosphate (ADP) B)cyclic adenosine monophosphate (cAMP) C)acetylcholine D)norepinephrine E)adrenaline

A drug that binds readily to available receptors,even if the concentration of drug is relatively low,is said to have _______ for that receptor. A)low specificity B)high affinity C)a short half-life D)all of the above E)none of the above

A drug that binds to a receptor and directly initiates a change in the function of the cell is referred to as: A)an agonist. B)an antagonist. C)a synergist. D)a compliment. E)none of the above

In contrast to an agonist,a pharmacologic antagonist: A)has affinity for the receptor,but lacks efficacy. B)is also known as a "blocker." C)can be used prevent endogenous chemicals from overstimulating the receptor. D)all of the above E)none of the above

A noncompetitive antagonist: A)has a more or less equal opportunity to occupy the receptor as the agonist. B)forms rather weak bonds with the receptor. C)produces inhibition that can be overcome by administering high concentrations of the agonist. D)all of the above E)none of the above

Overstimulation of postsynaptic receptors may lead to a decrease in the receptors' responsiveness.A brief and transient decrease in receptor responsiveness is known as _____,whereas a more prolonged process in which the actual number of available receptors is diminished is known as _________. A)down-regulation;desensitization B)desensitization;up-regulation C)up-regulation;desensitization D)down-regulation;autophosphorylation E)desensitization;down-regulation

A drug that fails to evoke a maximal response,even though it occupies all available receptors.is known as: A)a competitive antagonist. B)a noncompetitive antagonist. C)a partial agonist. D)a competitive agonist. E)an inverse antagonist.