Pharmacodynamics
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Questions and Answers

What does potency measure in pharmacology?

  • Amount of drug necessary to produce an effect (correct)
  • Receptor sensitivity to the drug
  • Maximum effect of the drug
  • Rate of absorption of the drug

    • How is potency often determined in pharmacology?

  • By assessing the maximum pharmacologic effect
  • By analyzing drug concentration at the receptor site
  • By calculating the EC50 value (correct)
  • Using the rate of metabolism of the drug

    • In pharmacology, what does the EC50 value represent?

  • Rate of absorption of the drug
  • Drug concentration at which all receptors are occupied
  • Amount of drug needed to achieve 50% of the maximum effect (correct)
  • Maximum effect of the drug

    • What information do graded dose-response curves provide in pharmacology?

    <p>Potency and efficacy of the drug</p> Signup and view all the answers

    What is the main consequence of autophosphorylation of the receptor when insulin binds to its subunits?

    <p>Activation of other important cellular signals</p> Signup and view all the answers

    How does the mechanism of Enzyme-linked Receptors differ from G protein–coupled receptors?

    <p>They involve autophosphorylation of the receptor</p> Signup and view all the answers

    What is a key requirement for ligands to interact with Intracellular Receptors?

    <p>Sufficient lipid solubility</p> Signup and view all the answers

    What happens after the activated ligand–receptor complex dimerizes in Intracellular Receptors?

    <p>It binds to transcription factors in the cell nucleus</p> Signup and view all the answers

    What is pharmacodynamics?

    <p>The study of drug actions on the body and how drug concentrations affect responses</p> Signup and view all the answers

    What happens when a drug binds to a receptor and activates it?

    <p>It initiates a series of reactions that lead to a specific response</p> Signup and view all the answers

    What role do receptors play in signal transduction?

    <p>They act as signal detectors</p> Signup and view all the answers

    How do cells respond to different types of agonists based on receptors?

    <p>By producing a unique response specific to each type of agonist</p> Signup and view all the answers

    What is the fundamental difference between competitive and noncompetitive antagonists?

    <p>Competitive antagonists reduce agonist potency, while noncompetitive antagonists reduce agonist efficacy.</p> Signup and view all the answers

    What effect does an allosteric antagonist have on the Emax and EC50 values of an agonist?

    <p>It causes a downward shift in Emax with no change in EC50.</p> Signup and view all the answers

    What is an example of an allosteric antagonist mentioned in the text?

    <p>Picrotoxin</p> Signup and view all the answers

    In what way does epinephrine counteract histamine-induced bronchoconstriction?

    <p>By acting as an agonist at B2-adrenoceptors and causing bronchial smooth muscle relaxation.</p> Signup and view all the answers

    Which characteristic is considered more clinically useful than potency in pharmacology?

    <p>Efficacy</p> Signup and view all the answers

    What determines a drug's ability to fully or partially activate receptors?

    <p>Intrinsic Activity</p> Signup and view all the answers

    Which term refers to drugs that produce a maximal biologic response similar to the endogenous ligand?

    <p>Full Agonists</p> Signup and view all the answers

    What is the intrinsic activity value of full agonists?

    <p>One</p> Signup and view all the answers

    What does potency refer to in pharmacology?

    <p>The amount of drug needed to produce an effect</p> Signup and view all the answers

    How can potency be determined in pharmacology?

    <p>By calculating the concentration of drug producing 50% of the maximum effect</p> Signup and view all the answers

    What characteristic can be determined by plotting graded dose-response curves?

    <p>Potency and efficacy of the drug</p> Signup and view all the answers

    In pharmacology, what does EC50 represent?

    <p>The concentration of drug producing 50% of the maximum effect</p> Signup and view all the answers

    What is a distinguishing feature of allosteric antagonists compared to competitive antagonists?

    <p>They reduce agonist efficacy</p> Signup and view all the answers

    How does an allosteric antagonist impact the Emax and EC50 values of an agonist?

    <p>Decreases Emax, no change in EC50</p> Signup and view all the answers

    Which receptor does epinephrine act on to counteract histamine-induced bronchoconstriction?

    <p>B2-adrenoceptors</p> Signup and view all the answers

    How does a noncompetitive antagonist differ from an allosteric antagonist in receptor binding?

    <p>Noncompetitive antagonists have higher affinity for the agonist-binding site</p> Signup and view all the answers

    What is the main effect of a decrease in the diameter of an arteriole on blood flow and pressure?

    <p>Increase in resistance and increase in blood pressure</p> Signup and view all the answers

    How do the dose–response curves of full agonists compare for receptor binding and biological responses?

    <p>They are parallel</p> Signup and view all the answers

    What happens to the Emax of a receptor saturated with an agonist in the presence of increasing concentrations of a partial agonist?

    <p>Emax decreases until it reaches the Emax of the partial agonist</p> Signup and view all the answers

    What role can a partial agonist play when exposed to a full agonist at the same receptor?

    <p>It acts as an antagonist to the full agonist</p> Signup and view all the answers

    An agonist binds to a site on a receptor protein and deactivates it, resulting in a specific intracellular response.

    <p>False</p> Signup and view all the answers

    Cells contain muscarinic receptors that bind and respond to epinephrine or norepinephrine.

    <p>False</p> Signup and view all the answers

    Second messenger molecules are not involved in translating agonist binding into a cellular response.

    <p>False</p> Signup and view all the answers

    Pharmacodynamics describes the actions of a drug on the body but not the influence of drug concentrations on the magnitude of the response.

    <p>False</p> Signup and view all the answers

    Ligand-gated ion channels can be regulated by voltage-gated ion channels.

    <p>False</p> Signup and view all the answers

    Stimulation of the nicotinic receptor by acetylcholine leads to potassium influx and sodium outflux.

    <p>False</p> Signup and view all the answers

    Partial agonists can have a greater effect than full agonists when exposed to the same receptor.

    <p>False</p> Signup and view all the answers

    G protein–coupled receptors do not recognize chemical signals that affect adenylyl cyclase activity.

    <p>False</p> Signup and view all the answers

    Receptors may be internalized within the cell, making them unavailable for further _____ interaction.

    <p>False</p> Signup and view all the answers

    During the recovery phase, unresponsive receptors are referred to as 'responsive'.

    <p>False</p> Signup and view all the answers

    Repeated exposure of a receptor to an antagonist results in down-regulation of receptors.

    <p>False</p> Signup and view all the answers

    Agonist drugs mimic the action of the endogenous ligand for the receptor.

    <p>True</p> Signup and view all the answers

    A drug with a lower EC50 value is considered more potent than a drug with a higher EC60 value.

    <p>True</p> Signup and view all the answers

    Efficacy of a drug is solely dependent on the number of drug receptor complexes formed.

    <p>False</p> Signup and view all the answers

    Partial agonists can reach the same maximal response as full agonists even when occupying 100% of the receptors.

    <p>False</p> Signup and view all the answers

    Maximal efficacy (Emax) occurs when the drug occupies all receptors, leading to no increase in response with higher drug concentrations.

    <p>True</p> Signup and view all the answers

    What is the main consequence of autophosphorylation of the receptor when insulin binds to its subunits?

    <p>Phosphorylation of other peptides or proteins</p> Signup and view all the answers

    What is the primary target of ligand-receptor complexes in Intracellular Receptors?

    <p>Transcription factors in the cell nucleus</p> Signup and view all the answers

    What does the activated ligand-receptor complex typically do after translocating to the nucleus in Intracellular Receptors?

    <p>Dimerizes before binding to transcription factors</p> Signup and view all the answers

    How does the mechanism of Enzyme-linked Receptors differ from G protein-coupled receptors?

    <p>Enzyme-linked receptors phosphorylate other peptides or proteins upon activation, while G protein-coupled receptors directly activate transcription factors</p> Signup and view all the answers

    What determines the magnitude of a drug effect according to the text?

    <p>Receptor sensitivity and drug concentration at the receptor site</p> Signup and view all the answers

    How is potency defined in pharmacology based on the text?

    <p>Amount of drug required to produce an effect</p> Signup and view all the answers

    What does the EC50 for Drugs A and B indicate according to the text?

    <p>Drug A is more potent than Drug B</p> Signup and view all the answers

    Which characteristic can be determined by plotting graded dose-response curves as mentioned in the text?

    <p>Potency and efficacy</p> Signup and view all the answers

    What distinguishes allosteric antagonists from competitive antagonists?

    <p>Allosteric antagonists bind to a site other than the agonist-binding site, causing a downward shift in Emax.</p> Signup and view all the answers

    How does functional antagonism typically work?

    <p>Functional antagonists bind to a separate receptor and initiate effects opposite those of the agonist.</p> Signup and view all the answers

    What is the specific effect of epinephrine on bronchial smooth muscle in response to histamine-induced bronchoconstriction?

    <p>Epinephrine counteracts histamine-induced bronchoconstriction by causing relaxation of the muscles.</p> Signup and view all the answers

    Which drug mentioned in the text illustrates allosteric antagonism at GABA-controlled chloride channels?

    <p>Picrotoxin</p> Signup and view all the answers

    Which of the following best describes drugs with low therapeutic indices?

    <p>They have a small range of effective doses and a non-overlapping range of toxic doses.</p> Signup and view all the answers

    In the context of quantal dose-response curves, what is the significance of a two- to threefold increase in the international normalized ratio (INR) for warfarin?

    <p>It indicates a desirable response to the drug.</p> Signup and view all the answers

    Why are some drugs with low therapeutic indices still used to treat serious diseases?

    <p>The risk of adverse effects outweighs the risk of leaving the disease untreated.</p> Signup and view all the answers

    What effect does bioavailability have on drugs with low therapeutic indices?

    <p>It is not critical for these drugs' therapeutic effects.</p> Signup and view all the answers

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