48 Questions
What does a semilogarithmic plot of the dose-response relationship allow for?
Graphing the complete range of doses
What characteristic makes candesartan more potent than irbesartan?
It has a lower EC50 value
What does maximal efficacy (Emax) of a drug imply?
The drug occupies all receptors and causes the highest response
What characteristic differs between full and partial agonists?
Maximal response
What is potency in the context of a drug's dose-response relationship?
The amount of drug needed to produce an effect
How is potency usually determined?
By the concentration of drug producing 50% of the maximum effect
What does a graded dose-response curve illustrate?
The relationship between drug concentration and pharmacologic effect
How can the EC50 for Drugs A and B be interpreted in terms of potency?
Drug A is more potent than Drug B
Which second messengers are generated by the activation of phospholipase C?
Inositol 1,2,5-trisphosphate (IP3) and diacylglycerol (DAG)
Which family of receptors possesses tyrosine kinase activity as part of their structure?
Enzyme-linked Receptors
What physiological effect is mediated by cAMP activation within the cell?
Regulation of protein kinases
What occurs when the enzyme-linked receptors are activated?
Conformational changes resulting in increased cytosolic enzyme activity
What is the defining characteristic of a competitive antagonist?
It interferes with an agonist binding to its receptor and maintains the receptor in its inactive state
How does an irreversible antagonist differ from a competitive antagonist?
It causes a downward shift of the Emax with no shift of EC50 values
What happens when the concentration of agonist is increased relative to a competitive antagonist?
It overcomes the inhibition caused by the antagonist
In what way do irreversible antagonists and allosteric antagonists behave similarly?
Both cause a downward shift of the Emax with no shift of EC50 values
Which type of ligands typically interact with receptors found on the cell surface?
Hydrophilic ligands
What type of receptors are membrane bound proteins that transduce extracellular signals into intracellular responses?
G protein-coupled receptors
Where is the ligand binding site usually located in ligand-gated ion channels?
Extracellular portion
Which type of ligand enters cells through the lipid bilayers of the cell membrane to interact with receptors found inside cells?
Hydrophobic ligands
What is the function of nicotinic receptors when stimulated by acetylcholine?
Inducing sodium influx and potassium outflux
Which type of receptors increase chloride influx and hyperpolarization of neurons when stimulated by an agonist?
GABA receptors
What effect do local anesthetics have on the voltage-gated sodium channel?
Inhibiting sodium influx and decreasing neuronal conduction
Which type of receptors are affected by the recognition of chemical signals by G protein–coupled membrane receptors?
Adenylyl cyclase
What does it mean for a drug to have a low therapeutic index?
It means the drug has a narrow range of effective doses and a high risk of toxic doses.
Why are some drugs with low therapeutic indices still used to treat serious diseases?
The risk of experiencing adverse effects is less than the risk of leaving the disease untreated.
What is the desired response to warfarin as its dose is increased?
A two- to threefold increase in the international normalized ratio (INR).
What happens at higher doses of warfarin?
Anticoagulation resulting in hemorrhage occurs in a small percent of patients.
What is the primary target of ligand–receptor complexes in the cell nucleus?
Transcription factors
What happens when the peptide hormone insulin binds to two of its receptor subunits?
The receptor itself autophosphorylates
How does the activation of enzyme-linked receptors result in a multiplication of the initial signal?
Phosphorylation of other peptides or proteins
What distinguishes the fourth family of receptors from the other three major receptor families?
The ligand must diffuse into the cell to interact with the receptor
What is the primary result of acetylcholine stimulation of the nicotinic receptor?
Sodium influx and potassium efflux
In what way do voltage-gated ion channels differ from ligand-gated ion channels?
Voltage-gated ion channels open in response to a ligand, while ligand-gated ion channels open due to changes in membrane potential.
How do local anesthetics affect the voltage-gated sodium channel?
They bind to the channel, inhibiting sodium influx and decreasing neuronal conduction.
What effect do G protein–coupled membrane receptors have on adenylyl cyclase activity?
They increase adenylyl cyclase activity.
What is the role of the α subunit of a G protein?
It binds guanosine triphosphate (GTP)
What is the function of adenylyl cyclase when activated by Gs and inhibited by Gi?
It produces cyclic adenosine monophosphate (cAMP)
What occurs when an agonist binds to a transmembrane G protein–coupled receptor?
It causes dissociation of the α-GTP complex from the βγ complex
What is the primary role of the intracellular domain of a transmembrane G protein–coupled receptor?
To interact with effector molecules
What characterizes the two states in which receptors exist?
Active and inactive reversible equilibrium states
What is the relationship between the magnitude of the biological effect and the fraction of active receptors (R*)?
The magnitude of the effect is directly related to the fraction of R*
What do partial agonists do in relation to the equilibrium of receptor states (R and R*)?
Shift the equilibrium towards R* less than full agonists
How are antagonists different from agonists in terms of the equilibrium of receptor states (R and R*)?
They stabilize the fraction of R, instead of increasing the fraction of R*
Which second messengers are generated by the activation of phospholipase C?
Inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG)
What is the primary target of inositol 1,4,5-trisphosphate (IP3) within the cell?
Regulation of calcium concentrations
Which family of receptors possesses tyrosine kinase activity as part of their structure?
Enzyme-linked Receptors
What physiological effect is mediated by cAMP activation within the cell?
Activation of protein kinases
Test your knowledge of dose-response relationships and potency in pharmacology and drug effects with this quiz. Questions cover topics like linear graphs, semilogarithmic plots, and the calculation of EC50 values.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
