Pharmacology Flashcards
What is affinity?
The strength of association between ligand and receptor
What is efficacy?
The ability of an agonist to provoke a cellular response
Do antagonists have affinity and efficacy?
No - they have affinity (bind to the receptor) but not efficacy (do not provoke a cellular response)
What is potency?
The concentration of a substance required to evoke a response
What does a competitive antagonist do to a dose-response curve?
Increases the concentration of agonist requires (dose) but does not reduce the maximal response
What does a non-competitive antagonist do to a dose-response curve?
Does not affect the dose, but reduces the maximal response
What are the 3 parts of a G-protein?
Alpha
Beta
Gamma
What does the alpha subunit of a G-protein contain?
A GTP/GDP binding site
Which part of a G protein binds to the effector?
The alpha subunit
How is a receptor which has been activated by a G-protein turned off?
The alpha subunit hydrolyses GTP to GDP and the signal is turned off
Note - the effector can be switched on even when the original molecule is still bound to the receptor
What does activation of M1 receptors do?
Increase neurotransmitter release
Increase acid secretion
What does activation of M2 receptors do?
Reduce heart rate and contractility
What does activation of M3 receptors do?
Visceral smooth muscle contraction (eg bronchial SM)
Increased mucosecretion
Vascular smooth muscle relaxation
What does activation of B1 receptors do?
Increased heart rate and contractility
What does activation of B2 receptors do?
Relaxation of bronchial and vascular smooth muscle
