Adrenergic Agonists and Receptor Activation Quiz

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What is the reason that catecholamines are ineffective if given orally?

They undergo rapid degradation by MAO and COMT

They are inactivated before they can reach systemic circulation (correct)

They lack a catechol group

They have a lower affinity for adrenergic receptors

What causes the pink or brown pigmentation in catecholamine-containing solutions over time?

Bacterial contamination

Reaction with light

Decomposition of the solution

Oxidation of the catecholamine molecule (correct)

How do noncatecholamines differ from catecholamines?

They undergo rapid degradation by MAO and COMT

They have a higher affinity for adrenergic receptors

They are substrates for COMT and metabolize slowly by MAO

They lack a catechol group and metabolize slowly by MAO (correct)

What is a significant characteristic of noncatecholamines in terms of their ability to cross the blood-brain barrier?

They are considerably less polar than catecholamines Signup and view all the answers

Which drug is highly selective, acting at B2 receptors only?

Albuterol Signup and view all the answers

At what doses does the selectivity of a drug to activate certain receptors decline?

As the dose increases Signup and view all the answers

What responses can be elicited by the activation of alpha-1 receptors?

Vasoconstriction and mydriasis Signup and view all the answers

Which enzymes are responsible for the quick metabolism of catecholamines?

Monoamine oxidase [MAO] and catechol-O-methyltransferase [COMT] Signup and view all the answers

What distinguishes indirect agonists from direct agonists in terms of their mechanism of action?

Direct agonists work on receptor binding, while indirect agonists work by promoting norepinephrine release. Signup and view all the answers

What chemical groups characterize catecholamines?

Catechol and amine groups Signup and view all the answers

Why can catecholamines not be used orally?

Because they are quickly metabolized by enzymes and have a brief duration of action Signup and view all the answers

What is the defining characteristic of noncatecholamines in relation to the blood-brain barrier?

They are unable to cross the blood-brain barrier Signup and view all the answers

What is the role of adrenergic agonists in activating adrenergic receptors?

Directly working on receptor binding Signup and view all the answers

What distinguishes catacholamines from noncatacholamines?

Catacholamines have a shorter duration of action than noncatacholamines Signup and view all the answers

Which group of drugs includes dopamine, epinephrine, isoproterenol, and ephedrine?

Indirect agonists Signup and view all the answers

What happens to catecholamines due to their chemistry?

They rapidly metabolize and cannot be used orally Signup and view all the answers

What is the role of noncatecholamines in relation to the blood-brain barrier?

They are unable to cross the blood-brain barrier like catecholamines Signup and view all the answers

What differentiates catecholamines from noncatecholamines in terms of oral use?

Catecholamines can be taken orally while noncatecholamines cannot Signup and view all the answers

What is the defining characteristic of adrenergic agonists known as sympathomimetics?

Their effects are similar to sympathetic nervous system activation due to using the same receptors Signup and view all the answers

What distinguishes catacholamines from noncatacholamines?

Availability for oral use, duration of action, and ability to act in the central nervous system Signup and view all the answers

What is the common structural feature of all catecholamines?

Hydroxyl groups on two adjacent carbons of a benzene ring Signup and view all the answers

Which enzyme is responsible for the rapid metabolism of catacholamines?

Catechol-O-methyltransferase [COMT] Signup and view all the answers

Why can't catacholamines be used orally?

They are rapidly metabolized by monoamine oxidase [MAO] and catechol-O-methyltransferase [COMT] Signup and view all the answers

Which class of adrenergic agonists includes dopamine and epinephrine?

Catecholamines Signup and view all the answers

What distinguishes indirect agonists from direct agonists?

Mechanism of receptor activation Signup and view all the answers

What is the common mechanism of action for indirect agonists?

Promotion of norepinephrine release, blockade of norepinephrine re uptake, and inhibition of norepinephrine inactivation Signup and view all the answers

Why do catacholamines have a brief duration of action?

Rapid metabolism by monoamine oxidase [MAO] and catechol-O-methyltransferase [COMT] Signup and view all the answers

What prevents catacholamines from crossing the blood-brain barrier?

The presence of efflux transporters Signup and view all the answers

What makes noncatacholamines different from catecholamines?

Their ability to be used orally and duration of action Signup and view all the answers

What is the primary mechanism through which noncatacholamines exert their effects?

Inhibition of norepinephrine inactivation Signup and view all the answers

Why are noncatecholamines able to act in the central nervous system unlike catecholamines?

They are not susceptible to metabolism by hepatic enzymes Signup and view all the answers

Adrenergic Agonists and Receptor Activation Quiz

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Questions and Answers

What is the reason that catecholamines are ineffective if given orally?

What causes the pink or brown pigmentation in catecholamine-containing solutions over time?

How do noncatecholamines differ from catecholamines?

What is a significant characteristic of noncatecholamines in terms of their ability to cross the blood-brain barrier?

Which drug is highly selective, acting at B2 receptors only?

At what doses does the selectivity of a drug to activate certain receptors decline?

What responses can be elicited by the activation of alpha-1 receptors?

Which enzymes are responsible for the quick metabolism of catecholamines?

What distinguishes indirect agonists from direct agonists in terms of their mechanism of action?

What chemical groups characterize catecholamines?

Why can catecholamines not be used orally?

What is the defining characteristic of noncatecholamines in relation to the blood-brain barrier?

What is the role of adrenergic agonists in activating adrenergic receptors?

What distinguishes catacholamines from noncatacholamines?

Which group of drugs includes dopamine, epinephrine, isoproterenol, and ephedrine?

What happens to catecholamines due to their chemistry?

What is the role of noncatecholamines in relation to the blood-brain barrier?

What differentiates catecholamines from noncatecholamines in terms of oral use?

What is the defining characteristic of adrenergic agonists known as sympathomimetics?

What distinguishes catacholamines from noncatacholamines?

What is the common structural feature of all catecholamines?

Which enzyme is responsible for the rapid metabolism of catacholamines?

Why can't catacholamines be used orally?

Which class of adrenergic agonists includes dopamine and epinephrine?

What distinguishes indirect agonists from direct agonists?

What is the common mechanism of action for indirect agonists?

Why do catacholamines have a brief duration of action?

What prevents catacholamines from crossing the blood-brain barrier?

What makes noncatacholamines different from catecholamines?

What is the primary mechanism through which noncatacholamines exert their effects?

Why are noncatecholamines able to act in the central nervous system unlike catecholamines?

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