Receptors 2 Flashcards
What is neurotransmission?
Chemical communication and therefore has a central role in almost every regulatory mechanism in our body.
Who was the receptor concept found by?
John Newport Langley in 1905.
How was the receptor concept found?
Nicotine was applied to frog skeletal muscle and it was found that the muscle only contracted when placed at the joint between the nerve and the muscle (motor end plate).
When it was applied to the nerve itself it had no effect
Who originated the quantitative receptor theory?
Alfred J Clark - it applied chemical laws to biological ideas.
What is a receptor?
A macromolecule that combines with a drug in order to produce effects.
How do drugs modify the function of different organ systems?
A pharmacodynamic interaction between the drug and the recognition system for that drug.
How can the response of muscle to a drug be measured?
A Kymograph (made by Matteucci) can record variations in muscular and physiological processes. It was based on a rotating drum that was smoked with benzene and a scribe scratched a recording of the experiment.
What is an agonist response?
A response in which the drug produces a response.
Why is a graph of concentration against response not useful for pharmacologists?
Only the lower concentrations of the drug are useful - hard to see from this type of graph.
What graph is more useful?
A log scale of concentration - a sigmoid graph is produced and the EC50 can be calculated by drawing a line at the 50% reponse.
The log concentration transforms curve from rectangular parabola to sigmoid curve
What can EC50s be used for?
They can be compared to work out how much more potent a certain drug is compared to another.
What is pEC50?
-log(EC50), measures drug potency.
What is intrinsic efficacy?
The ability of a drug to stimulate tissue - the ability of a molecule to force a receptor into its active state, which is the state leading to cellular response.
What are antagonists?
Drugs that bind to receptors that don’t cause an effect themselves but block responses produced by agonists.
receptor antagonists have affinity for the receptor but no intrinsic efficacy (ability to produce reponse)
What do antagnonists do the potency of agonists?
They reduce the potency so larger doses are required for the same effects.
What is a competitive antagonist?
When the antagonist competes for the same site of the agnonist.
What are partial agonists?
Ligands that show some agonist activity but do not produce full responses and block responses produced by full agonists at the receptor.
Simplify the term for a strong partial agonist.
A strong agonist and a weak antagonist.
Simpify the term for a weak partial agonist.
A weak agonist and a strong antagonist.
What is affinity?
The ability of a drug to bind to a receptor.
What is potency?
A measure of drug activity expressed in terms of the amount required to produce an effect of given intensity.
What gives potency?
The combined effects of affinity and efficacy.
What forces control affinity?
Thermodynamic and chemical (vary depending on distance between drug and receptor - electrostatic, hydrogen, van der Waals, hydrophobic).
come back and do that long equation please
please
