essential pharmacology Flashcards
What are the basic functions of receptors?
Enable specificity and evoke an appropriate response.
What is a receptor?
A protein that recognises a specific compound or molecule. This can inhibit or trigger effects.
Define agonist and antagonist.
Agonists mimic the normal effects of a receptor. Antagonists block the normal effects of a receptor.
Describe the relationship between agonist concentration and effect.
As agonist concentration increases, more receptors are occupied and so effect increases. Only works until receptor becomes saturated.
What is the affinity of a drug for a receptor?
The strength of the chemical reaction between the drug and receptor. Low EC50? High affinity.
Explain the idea of efficacy of an agonist.
How good an agonist is at activating a particular receptor.
Name the 4 types of membrane receptors that can signal across membranes.
Ionatropic, intrinsic enzyme activity, interactions with JAK kinases (JAK-STAT) and interactions with G-proteins (serpentine).
What would happen if a G-protein was coupled to adenylyl cyclase?
Increases or decreases the concentrations of cAMP (2nd messenger). Activates or inhibits PKA.
What would happen if a G-protein was coupled to phospholipase C?
Produces diacylglycerol and inositol triphosphate. Activates PKC and releases internal Ca2+ stores.
Define the sources of intracellular calcium (2nd messenger).
Internal stores via calcium triggered release from the ER. From outside the cell via ligand- and voltage-gated channels. Also, by inhibiting Ca2+ transport out of the cell.
Which types of chemical messengers can enter cells?
Lipid-soluble ones - steroid hormones and NO.
Define the properties of full agonists, partial agonists and antagonists.
Full agonist: high affinity and high efficacy. Partial agonist: high affinity and moderate efficacy. Antagonist: high affinity and low efficacy.
