Essential Pharmacology Flashcards
Describe the basic function of receptors involved in intercellular communication.
The cell will release its chemical signal (e.g. NT or hormone).
Different receptors for the same chemical signals can produce a different response in different cells.
= specificity
= signal transduction
Describe the basic function of intracellular receptors.
Inside cell (cytosol or nucleus).
Signalling molecules may be lipid soluble so can dissolve through lipid bilayer.
(e.g. steroid hormone receptors = transcription factors).
Describe the basic function of ionotropic cell surface receptors.
The receptors are channels.
Rapid diffusion compared to rest.
(e.g. nicotinic acetylcholine receptors).
Describe the basic function of metabotropic cell surface receptors.
G-protein coupled receptors.
All work is done by G-protein (takes longer).
Different G-proteins couple to different 2nd messenger systems.
Describe the basic function of receptor enzymes.
Receptors with intrinsic enzyme activity.
Bound to an enzyme (e.g. cytokines)
Describe basic function of integrin receptors.
Receptors that interact with the cytoskeleton.
Describe Adenylyl Cyclase as an example of G-protein coupled receptor.
Adenylyl cyclase produces cAMP as its 2nd messenger. This regulates protein kinase A activity, which phosphorylates target proteins and changes their activity.
Define the sources of intracellular calcium.
From internal stores via IP3- or Ca2+ stimulated release from endoplasmic reticulum.
From outside of cell via voltage or ligand gated channels.
Via inhibition of Ca2= transport out of cell.
Define what is meant by a receptor.
A receptor is the binding site that is bound to by signalling molecules (e.g. drugs).
Explain the terms agonist and antagonist.
Agonists mimic the normal effect of response. Agonists have high affinity and efficacy to the signal.
Antagonists block the normal action of the receptor. They have high affinity and low efficacy.
Define affinity and efficacy.
Affinity is how readily the signal binds to the receptor.
Efficacy is how well it activates the receptor.
Describe the relationship between agonist concentration and effect.
The more agonists you have present, the larger the response.
It is likely that there is a limited number of receptors so the response will likely become the maximum (saturated) response.
Describe what is meant by a selective agonist/antagonist.
Selective agonists are drugs that activate only some of those receptors.
Selective antagonists are drugs that block only some of these receptors.
Describe the clinical importance of selective agonists and antagonists.
By ensuring that drugs are selective agonists/antagonists and only act on specific receptors, this removes the opportunity for side-affects to interfere.
Describe propranolol as a selective B1 and B2 antagonist.
Propranolol is used in the treatment of arrythmias.
Propranolol binds to the B1 receptors in the heart and prevents adrenaline and noradrenaline from increasing heart rate.
