Week 32/Nervous System 3 Flashcards
(40 cards)
Q: What is a receptor?
A: A receptor is a protein molecule that receives chemical signals from outside a cell, and it can lead to various physiological responses.
Q: How can receptors vary despite having the same endogenous ligand?
A: The same endogenous ligand can bind to a large number of receptor subtypes, and these subtypes are widespread throughout the nervous system, providing a diversity of functions.
Q: What are the two main types of receptors based on their mechanism of action?
A: Receptors can be either ligand-gated or G-protein coupled.
Q: What is a ligand?
A: A ligand is a substance that forms a complex with a biomolecule (such as a receptor) to serve a biological purpose.
Q: What is a prodrug?
A: A prodrug is a chemical compound that must undergo chemical conversion by metabolic processes before it becomes an active pharmacological agent.
Q: How does diamorphine (heroin) work as a prodrug?
A: Diamorphine enters the brain and is converted into morphine, which then binds to mu (μ) opioid receptors to exert its effects.
Q: What does bioavailability refer to?
A: Bioavailability refers to the extent and rate at which the active drug or metabolite enters systemic circulation.
Q: What is affinity in the context of drug-receptor interactions?
A: Affinity describes how tightly a drug binds to its receptor.
Q: What does efficacy mean in pharmacology?
A: Efficacy refers to the capacity of a drug to produce a change in a target cell or organ after binding to its receptor.
Q: What is potency in terms of drug activity?
A: Potency is a measure of drug activity expressed in terms of the amount required to produce an effect of given intensity.
Q: What does an agonist do to the post-synaptic neuron?
A: An agonist can produce either excitation or inhibition of the post-synaptic neuron.
Q: What is an agonist?
A: An agonist is a neurotransmitter or drug that mimics the action of a neurotransmitter and binds to its cognate receptor, producing a response. A neurotransmitter itself is an agonist, with high affinity for its own receptor.
Q: What is a partial agonist?
A: A partial agonist is a ligand that produces a lower response than a full agonist after binding to the same number of receptors.
Q: What is an inverse agonist?
A: An inverse agonist is a ligand that selectively binds to the inactive state of a receptor and reduces its constitutive activity, producing the opposite effect of an agonist.
Q: What is constitutive receptor activity?
A: Receptors can be active without an activating ligand, displaying “constitutive activity.”
Q: How can a partial agonist act as a competitive antagonist?
A: A partial agonist can act as a competitive antagonist when in the presence of a full agonist, because it competes for the same receptor sites but produces a weaker response.
Q: How does an inverse agonist affect receptor activity?
A: An inverse agonist decreases receptor activity below the basal level, suppressing spontaneous receptor signaling when present.
Q: How do agonists and inverse agonists differ in their effects?
A: - An agonist increases receptor activity above its basal level.
An inverse agonist decreases receptor activity below its basal level.
Q: Can inverse agonists and agonists be blocked?
A: Yes, the effects of both agonists and inverse agonists can be blocked by antagonists.
Q: What type of receptors commonly display constitutive activity?
A: Most, if not all, G-protein-coupled receptors (GPCRs) can display constitutive receptor activity.
Q: What is the main pharmacological effect of inverse agonists?
A: Receptor antagonism.
Q: When do inverse agonists behave as antagonists?
A: In the absence of constitutive receptor activity, inverse agonists function as antagonists.
Q: What is constitutive receptor activity?
A: The activation of receptors and production of a second messenger without the binding of an agonist.
Q: When is the effect of inverse agonists on constitutive activity relevant?
A: Only if the system is spontaneously active.
