Principles of Drug Action Quiz

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Questions and Answers

What determines the quantitative relations between the dose/concentration of a drug and its pharmacologic effects?

Receptors (correct)

Hormones

Enzymes

Antibodies

Which property of receptors determines the concentration of drug required to form drug-receptor complexes?

Shape

Affinity for binding a drug (correct)

Color

Size

What limits the maximal effect a drug may produce?

Drug color

Blood volume

Temperature

Total number of receptors (correct)

What term refers to the capacity of a receptor to respond to a drug's ability to stimulate at a specified dose?

Sensitivity Signup and view all the answers

What property of a receptor is linked to the dose required to produce an effect?

Sensitivity Signup and view all the answers

Which factor is responsible for the selectivity of drug action?

Receptors Signup and view all the answers

What term is used to describe a recognition molecule for a chemical mediator that can change its conformation to regulate cellular activity?

Receptor Signup and view all the answers

Where do most receptors bind with their ligands?

On the cell membrane Signup and view all the answers

Which type of ligand binds to the primary or orthosteric sites of a receptor?

Endogenous agonist Signup and view all the answers

What does adrenaline bind to in the heart to increase the heartbeat?

Beta receptors Signup and view all the answers

Which type of ligand may act on allosteric sites of a receptor?

Positive allosteric modulator Signup and view all the answers

What do receptors determine in relation to drug dose/concentration and pharmacologic effects?

Quantitative relations Signup and view all the answers

What is the function of ligand-gated ion channels?

Control the flow of ions across the membrane Signup and view all the answers

Which type of receptors are regulatory proteins attached to DNA known as?

Nuclear receptors Signup and view all the answers

What serves as the effector in a ligand-gated ion channel?

Ion channel Signup and view all the answers

Which type of receptors are also called ionotropic receptors?

Ligand-gated ion channels Signup and view all the answers

What is the primary function of G-proteins in G-protein-coupled receptors (GPCRs)?

Act as molecular switches for cellular responses Signup and view all the answers

Which class of receptors detects molecules outside the cell and activates internal pathways?

G-protein-coupled receptors Signup and view all the answers

What is the main function of GPCRs in signal transduction?

Activate diverse G-protein complexes Signup and view all the answers

What is the role of effector proteins in GPCR signaling?

Create second messengers Signup and view all the answers

How does signal termination occur in GPCR signaling?

GTP is converted back to GDP inactivating the G-protein Signup and view all the answers

Which factor plays a crucial role in transferring information from the environment to a cell's interior in signal transduction?

GPCRs Signup and view all the answers

What is the primary function of activated protein kinases in GPCR signaling?

Phosphorylate multiple cellular proteins Signup and view all the answers

Why is it necessary for GPCR signaling cascades to end?

To terminate the cascade initiated by ligand binding Signup and view all the answers

What is the main role of protein phosphorylation of intracellular proteins?

Regulate cellular effects Signup and view all the answers

What is the function of cytokine or growth factor receptor in the JAK-STAT pathway?

Initiate gene expression Signup and view all the answers

Which enzymes are responsible for phosphorylating tyrosine residues on cytokine receptors in the JAK-STAT pathway?

Janus kinases (JAKs) Signup and view all the answers

What is the downstream effect of bound STATs in the JAK-STAT pathway?

Induce inflammation and growth Signup and view all the answers

How do cytokine receptors differ from tyrosine kinase receptors in terms of kinase activity?

Cytokine receptors lack intrinsic kinase activity Signup and view all the answers

Which type of receptors are predominantly activated by peptide hormones like insulin and growth factors?

Enzyme-linked receptors Signup and view all the answers

Study Notes

Pharmacologic Effects of Drugs

Quantitative relations between dose/concentration and pharmacologic effects: Determined by the properties of the drug and the receptor it interacts with.
Concentration required to form drug-receptor complexes: Determined by the receptor's affinity for the drug.
Maximum effect a drug can produce: Limited by the number of receptors available for binding.

Receptor Properties

Efficacy: Receptor's ability to stimulate at a specified dose.
Affinity: Property linked to the dose required to produce an effect.
Selectivity of drug action: Determined by the receptor's specific structure and affinity for certain drugs.

Receptors: Recognition & Regulation

Receptor: Recognition molecule for a chemical mediator that changes its conformation to regulate cellular activity.
Ligand-binding: Most receptors bind to their ligands at the cell membrane level.
Orthosteric ligands: Bind to the primary or orthosteric sites of a receptor.
Adrenaline in the heart: Binds to β-adrenergic receptors to increase heart rate.
Allosteric ligands: May act on allosteric sites of a receptor, altering its affinity for orthosteric ligands.
Receptor's role: Determines the relationship between drug dose, concentration, and the resulting pharmacologic effects.

Types of Receptors & Their Functions

Ligand-gated ion channels: Control ion flow across the membrane in response to ligand binding, changing the membrane potential.
Nuclear receptors: Regulatory proteins attached to DNA, mediating the effects of steroid and thyroid hormones.
Effector in ligand-gated ion channels: The ion channel itself.
Ionotropic receptors: Also known as ligand-gated ion channels.
G-proteins in GPCRs: Primary function is to act as signal transducers, relaying information from activated receptors to effector proteins.
G-protein-coupled receptors (GPCRs): Detect molecules outside the cell and activate internal pathways.
GPCRs in signal transduction: Main function is to initiate signal cascades that amplify the cellular response to extracellular signals.
Effector proteins in GPCR signaling: Carry out the ultimate biological response.
Signal termination in GPCR signaling: Occurs through intrinsic GTPase activity of the α subunit, hydrolysis of GTP to GDP, and reassociation of the G-protein subunits.
Signal transduction: Receptors play a crucial role in transferring information from the environment to a cell's interior.
Activated protein kinases in GPCR signaling: Function is to phosphorylate target proteins, altering their activity and inducing a biological response.
Termination of GPCR signaling cascades: Essential to prevent continuous stimulation and maintain cellular homeostasis.
Protein phosphorylation of intracellular proteins: Main role is to regulate protein activity and function.

JAK-STAT Pathway

Cytokine or growth factor receptor: Receptor that initiates the JAK-STAT pathway.
JAK enzymes: Tyrosine kinases that phosphorylate tyrosine residues on cytokine receptors.
Bound STATs: After phosphorylation, STATs dimerize and translocate to the nucleus to activate gene transcription.
Cytokine receptors vs. tyrosine kinase receptors: Cytokine receptors themselves lack intrinsic kinase activity, relying on JAKs, while tyrosine kinase receptors have intrinsic tyrosine kinase activity.

Tyrosine Kinase Receptors

Tyrosine kinase receptors: Predominantly activated by peptide hormones like insulin and growth factors.

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Description

Test your knowledge on the principles of drug action with examples like adrenaline binding to ß-receptors on the heart and estrogen binding to estrogen receptors on the breast. Understand how receptors determine the quantitative relations between drug dose/concentration and pharmacologic effects.