Question 1

The primary location for receptors that recognize drugs and endogenous compounds is:&#10;A)on the cell's surface.&#10;B)in the cell's cytoplasm.&#10;C)on the cell's nuclear membrane.&#10;D)on the cell's chromosomes.&#10;E)on the ribosomes.

Accepted Answer

Receptors that recognize drugs and endogenous compounds are typically located on the cell's surface, allowing for easy communication and interaction with external ligands. This allows for efficient and rapid signaling between cells, allowing for effective physiological responses. Receptors located in the cell's cytoplasm or nucleus are typically involved in intracellular signaling and are more commonly associated with hormones or transcription factors. Receptors located on chromosomes or ribosomes are less common and typically serve specific functions within those structures.

Question 2

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

cyclic adenosine monophosphate (cAMP)

Accepted Answer

Adenylate cyclase hydrolyzes ATP into cyclic adenosine monophosphate (cAMP), which serves as a second messenger within the cell. Therefore, drugs that affect the function of adenylate cyclase will ultimately affect cAMP levels and downstream enzyme activation. The other choices (acetylcholine, norepinephrine, and adrenaline) are neurotransmitters or hormones, and are not directly involved in the adenylate cyclase pathway.

Question 3

A drug that binds readily to available receptors,even if the concentration of drug is relatively low,is said to have _______ for that receptor.&#10;A)low specificity&#10;B)high affinity&#10;C)a short half-life&#10;D)all of the above&#10;E)none of the above

Accepted Answer

High affinity refers to the ability of a drug to bind readily to available receptors even with low drug concentration. Therefore, the option B is the correct answer. Option A (low specificity) refers to the ability of a drug to bind to multiple types of receptors, while option C (short half-life) refers to the time it takes for half of the drug to be eliminated from the body. Option D includes all three options, which is incorrect in this case. Option E (none of the above) is also incorrect as option B is the correct answer.

Question 4

A drug that binds to a receptor and directly initiates a change in the function of the cell is referred to as:&#10;A)an agonist.&#10;B)an antagonist.&#10;C)a synergist.&#10;D)a compliment.&#10;E)none of the above

Accepted Answer

A drug that binds to a receptor and directly initiates a change in the function of the cell is referred to as an agonist. An agonist can activate, enhance or mimic the effect of an endogenous substance that binds to the same receptor.

Question 5

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

Accepted Answer

The intermediate regulatory proteins that are activated by binding guanine nucleotides are called G proteins, specifically GTP-binding proteins. Therefore, the best choice is E, "G."

Question 6

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

Accepted Answer

Desensitization refers to a brief and transient decrease in receptor responsiveness, while down-regulation refers to a more prolonged process where the number of receptors is reduced.

Question 7

The acetylcholine receptor located on the postsynaptic membrane of the skeletal neuromuscular junction is an example of a membrane receptor that:&#10;A)is directly linked to an intracellular enzyme.&#10;B)is directly linked to a regulatory G protein.&#10;C)functions as an ion channel or pore.&#10;D)moves (translocates)to the cell's nucleus when stimulated.&#10;E)none of the above

Accepted Answer

The acetylcholine receptor located on the postsynaptic membrane of the skeletal neuromuscular junction functions as an ion channel or pore. When acetylcholine binds to the receptor, it causes the channel to open, allowing ions such as sodium and potassium to flow across the membrane and initiate muscle contraction.

Question 8

In contrast to an agonist,a pharmacologic antagonist:&#10;A)has affinity for the receptor,but lacks efficacy.&#10;B)is also known as a &#34;blocker.&#34;&#10;C)can be used prevent endogenous chemicals from overstimulating the receptor.&#10;D)all of the above&#10;E)none of the above

Accepted Answer

A pharmacologic antagonist has affinity for the receptor, but lacks efficacy, thus it can prevent endogenous chemicals from overstimulating the receptor. It is also known as a "blocker."

Question 9

A noncompetitive antagonist:&#10;A)has a more or less equal opportunity to occupy the receptor as the agonist.&#10;B)forms rather weak bonds with the receptor.&#10;C)produces inhibition that can be overcome by administering high concentrations of the agonist.&#10;D)all of the above&#10;E)none of the above

Accepted Answer

A noncompetitive antagonist binds to a different site than the agonist or irreversibly to the same site, reducing the maximal effect of the agonist, and its effects cannot be overcome by increasing agonist concentration.

Question 10

A drug that fails to evoke a maximal response,even though it occupies all available receptors.is known as:&#10;A)a competitive antagonist.&#10;B)a noncompetitive antagonist.&#10;C)a partial agonist.&#10;D)a competitive agonist.&#10;E)an inverse antagonist.

Accepted Answer

A drug that fails to evoke a maximal response despite occupying all available receptors is known as a partial agonist. Partial agonists bind to receptors but only activate them to a certain extent, resulting in a submaximal response. This is different from competitive antagonists, which bind to receptors but do not activate them, and noncompetitive antagonists, which bind to allosteric sites on receptors and prevent their activation by agonists. Competitive agonists, on the other hand, are drugs that bind to receptors and activate them to produce a maximal response, but can be displaced by other ligands with higher affinity. "Inverse antagonist" is not a recognized term in pharmacology.

Deck 4: Drug Receptors