pharmacology_questions_answers Flashcards
What are the four main targets for drugs in the body?
Receptors, Ion Channels, Carriers, Enzymes
What do receptors on cell surfaces do when they recognize and respond to ligands?
They activate the receptor, causing downstream effects.
Describe how ligand-gated ion channels work.
Ligand binding causes the gate to open or close, increasing or decreasing permeability to selected ions, changing membrane potential through depolarization or hyperpolarization.
Explain how GPCRs function.
Ligand binding causes a conformational change, leading to the exchange of GDP for GTP in the alpha subunit, dissociation of alpha and beta subunits, and regulation of target proteins. GTP hydrolyzes to GDP, continuing the cycle.
Where are GPCRs found, and what structural features do they have?
Only in eukaryotes, with seven transmembrane domains, coupled with heterotrimeric G-proteins that bind GDP or GTP.
What are the three subunits of G-proteins, and how do they interact with GDP and GTP?
Alpha, beta, and gamma subunits, interacting with GDP and GTP.
Describe how kinase-linked receptors function.
Include receptor tyrosine kinases (RTKs) and cytokine receptors. Ligand binding causes receptor dimerization and phosphorylation of tyrosine residues, increasing downstream effects, mediating growth factors, cytokines, and hormones at the gene transcription level.
Where are nuclear/intracellular receptors located, and what activates them?
In the cytoplasm (Class 1), nucleus (Class 2), or endocrine system (hybrid class), activated by lipophilic molecules affecting gene expression.
What forces affect a drug’s affinity for its target?
Van der Waals forces, hydrophobic interactions, ionic bonds, hydrogen bonds, and covalent bonds.
Define agonist and antagonist in terms of receptor interaction.
Agonist: Binds and activates or deactivates the receptor, producing a response. Antagonist: Binds to the receptor but causes no activity, blocking other molecules from binding.
What is the difference between a partial agonist and a full agonist?
Partial agonist: Intermediate efficacy, producing a sub-maximal effect even when all receptors are occupied. Full agonist: High efficacy, producing a maximal effect.
What is an inverse agonist?
Selectively binds to resting states of receptors, not activating them.
Describe the affinity and efficacy of antagonists.
Antagonists have affinity but zero efficacy.
Explain the types of competitive antagonism.
Competitive Reversible: Competes with agonists; higher concentration is favored. Shifts dose-response curve rightward. Competitive Irreversible: Competes but cannot be reversed by increasing agonist concentration. Shifts curve right and reduces efficacy. Non-Competitive: Binds to an allosteric site, reducing efficacy and shifting the dose-response curve right.
How do ligand-gated ion channels function?
Binding of a ligand causes a conformational change, allowing ions to move down the concentration gradient, causing depolarization or hyperpolarization.
