Essential Pharmacology Flashcards
Not done
What is a receptor?
Protein that a specific chemical messenger can bind to
to cause a specific response
Why do receptors enable specificity?
Only the correct chemical messenger can bind
Receptors have different responses
What are the basic types of membrane receptors? (4)
Receptor with ion channel
Receptor with intrinsic enzyme
Receptor directly liked to an enzyme
Receptor that activates an protein via G proteions
In the context of G-protein coupled receptors, what is the 2nd messenger?
Molecule produced using linked enzyme
enzyme activated by G proteins
Some receptors are not in the membrane, but are intracellular.
Only specific messengers can get into the cell and bind to them.
What are the 2 key messengers, and what makes them able to do so?
Steroid hormones
NO - nitric oxide
Lipid soluble
On the concentration response curve, the graph tails off at high [drug].
Why is this?
At low [drug] most receptors vacant so additional ligands are able to hit a vacant receptor
At high [drug], few vacant receptors so additional ligands has a lower chance of bumping into vacant receptor
What is the EC50, and which graph do you determine it from?
[drug] at which there is half of maximal response
Log [drug] vs response
What is the affinity of a drug?
Strength of chemical attraction between drug and receptor
What does a low EC50 value indicate about the affinity of a drug?
High affinity
What is efficacy?
How effective the drug is at activating the receptor
True or false
A drug that has a low efficacy must have a high EC50 value
False
Efficacy does not have an effect on EC50
What is the similarity between an agonist and an antagonist?
Both have high affinity
Antagonists have low efficacy - act as blockers
Some endogenous agonists act on several different receptors causing many different effects.
Why are selective agonist/antagonist drugs useful in this context?
Can enhance or block specific effects of these endogenous transmitters by only binding to one type of receptor
What effect will a competitive antagonist have on the log [drug] v response graph of an agonist?
Right shift
At same [drug], there is a lower response
What are the main types of G protein coupled receptors?
Adenylyl cyclase coupled
Phospholipase C coupled
Ion channel coupled
