Dose-Response Relationship and Potency Quiz
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Questions and Answers

What does a semilogarithmic plot of the dose-response relationship allow for?

  • Calculating the EC50 value directly
  • Understanding the magnitude of response
  • Graphing the complete range of doses (correct)
  • Determining the intrinsic activity of the drug

    • What characteristic makes candesartan more potent than irbesartan?

  • It occupies all the receptor sites
  • It has higher maximal response
  • It interacts with a greater number of receptors
  • It has a lower EC50 value (correct)

    • What does maximal efficacy (Emax) of a drug imply?

  • The drug spans a wide range of doses
  • The drug has the lowest EC50 value
  • The drug interacts with a large number of receptors
  • The drug occupies all receptors and causes the highest response (correct)

    • What characteristic differs between full and partial agonists?

    <p>Maximal response</p> Signup and view all the answers

    What is potency in the context of a drug's dose-response relationship?

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

    How is potency usually determined?

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

    What does a graded dose-response curve illustrate?

    <p>The relationship between drug concentration and pharmacologic effect</p> Signup and view all the answers

    How can the EC50 for Drugs A and B be interpreted in terms of potency?

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

    Which second messengers are generated by the activation of phospholipase C?

    <p>Inositol 1,2,5-trisphosphate (IP3) and diacylglycerol (DAG)</p> Signup and view all the answers

    Which family of receptors possesses tyrosine kinase activity as part of their structure?

    <p>Enzyme-linked Receptors</p> Signup and view all the answers

    What physiological effect is mediated by cAMP activation within the cell?

    <p>Regulation of protein kinases</p> Signup and view all the answers

    What occurs when the enzyme-linked receptors are activated?

    <p>Conformational changes resulting in increased cytosolic enzyme activity</p> Signup and view all the answers

    What is the defining characteristic of a competitive antagonist?

    <p>It interferes with an agonist binding to its receptor and maintains the receptor in its inactive state</p> Signup and view all the answers

    How does an irreversible antagonist differ from a competitive antagonist?

    <p>It causes a downward shift of the Emax with no shift of EC50 values</p> Signup and view all the answers

    What happens when the concentration of agonist is increased relative to a competitive antagonist?

    <p>It overcomes the inhibition caused by the antagonist</p> Signup and view all the answers

    In what way do irreversible antagonists and allosteric antagonists behave similarly?

    <p>Both cause a downward shift of the Emax with no shift of EC50 values</p> Signup and view all the answers

    Which type of ligands typically interact with receptors found on the cell surface?

    <p>Hydrophilic ligands</p> Signup and view all the answers

    What type of receptors are membrane bound proteins that transduce extracellular signals into intracellular responses?

    <p>G protein-coupled receptors</p> Signup and view all the answers

    Where is the ligand binding site usually located in ligand-gated ion channels?

    <p>Extracellular portion</p> Signup and view all the answers

    Which type of ligand enters cells through the lipid bilayers of the cell membrane to interact with receptors found inside cells?

    <p>Hydrophobic ligands</p> Signup and view all the answers

    What is the function of nicotinic receptors when stimulated by acetylcholine?

    <p>Inducing sodium influx and potassium outflux</p> Signup and view all the answers

    Which type of receptors increase chloride influx and hyperpolarization of neurons when stimulated by an agonist?

    <p>GABA receptors</p> Signup and view all the answers

    What effect do local anesthetics have on the voltage-gated sodium channel?

    <p>Inhibiting sodium influx and decreasing neuronal conduction</p> Signup and view all the answers

    Which type of receptors are affected by the recognition of chemical signals by G protein–coupled membrane receptors?

    <p>Adenylyl cyclase</p> Signup and view all the answers

    What does it mean for a drug to have a low therapeutic index?

    <p>It means the drug has a narrow range of effective doses and a high risk of toxic doses.</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 experiencing adverse effects is less than the risk of leaving the disease untreated.</p> Signup and view all the answers

    What is the desired response to warfarin as its dose is increased?

    <p>A two- to threefold increase in the international normalized ratio (INR).</p> Signup and view all the answers

    What happens at higher doses of warfarin?

    <p>Anticoagulation resulting in hemorrhage occurs in a small percent of patients.</p> Signup and view all the answers

    What is the primary target of ligand–receptor complexes in the cell nucleus?

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

    What happens when the peptide hormone insulin binds to two of its receptor subunits?

    <p>The receptor itself autophosphorylates</p> Signup and view all the answers

    How does the activation of enzyme-linked receptors result in a multiplication of the initial signal?

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

    What distinguishes the fourth family of receptors from the other three major receptor families?

    <p>The ligand must diffuse into the cell to interact with the receptor</p> Signup and view all the answers

    What is the primary result of acetylcholine stimulation of the nicotinic receptor?

    <p>Sodium influx and potassium efflux</p> Signup and view all the answers

    In what way do voltage-gated ion channels differ from ligand-gated ion channels?

    <p>Voltage-gated ion channels open in response to a ligand, while ligand-gated ion channels open due to changes in membrane potential.</p> Signup and view all the answers

    How do local anesthetics affect the voltage-gated sodium channel?

    <p>They bind to the channel, inhibiting sodium influx and decreasing neuronal conduction.</p> Signup and view all the answers

    What effect do G protein–coupled membrane receptors have on adenylyl cyclase activity?

    <p>They increase adenylyl cyclase activity.</p> Signup and view all the answers

    What is the role of the α subunit of a G protein?

    <p>It binds guanosine triphosphate (GTP)</p> Signup and view all the answers

    What is the function of adenylyl cyclase when activated by Gs and inhibited by Gi?

    <p>It produces cyclic adenosine monophosphate (cAMP)</p> Signup and view all the answers

    What occurs when an agonist binds to a transmembrane G protein–coupled receptor?

    <p>It causes dissociation of the α-GTP complex from the βγ complex</p> Signup and view all the answers

    What is the primary role of the intracellular domain of a transmembrane G protein–coupled receptor?

    <p>To interact with effector molecules</p> Signup and view all the answers

    What characterizes the two states in which receptors exist?

    <p>Active and inactive reversible equilibrium states</p> Signup and view all the answers

    What is the relationship between the magnitude of the biological effect and the fraction of active receptors (R*)?

    <p>The magnitude of the effect is directly related to the fraction of R*</p> Signup and view all the answers

    What do partial agonists do in relation to the equilibrium of receptor states (R and R*)?

    <p>Shift the equilibrium towards R* less than full agonists</p> Signup and view all the answers

    How are antagonists different from agonists in terms of the equilibrium of receptor states (R and R*)?

    <p>They stabilize the fraction of R, instead of increasing the fraction of R*</p> Signup and view all the answers

    Which second messengers are generated by the activation of phospholipase C?

    <p>Inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG)</p> Signup and view all the answers

    What is the primary target of inositol 1,4,5-trisphosphate (IP3) within the cell?

    <p>Regulation of calcium concentrations</p> Signup and view all the answers

    Which family of receptors possesses tyrosine kinase activity as part of their structure?

    <p>Enzyme-linked Receptors</p> Signup and view all the answers

    What physiological effect is mediated by cAMP activation within the cell?

    <p>Activation of protein kinases</p> Signup and view all the answers

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