Essential Pharmacology Flashcards
How is receptor specificity maintained?
Chemical messengers (e.g. NT/hormones) only fit certain receptors and so will only produce a response in specific cells with that receptor.
Can receptors be coupled?
The same receptor can be coupled to trigger a different response in different cells- one cell can have many of the same or different receptors.
What are intracellular receptors?
Intracellular receptors are lipid-soluble (e.g. steroid hormones)- they can cross the cell membrane therefor act on receptors in the cell, including on the nucleus (transcription factors etc).
What is an example of an intracellular receptor?
Nitrogen oxide.
Why can intracellular receptors have direct action on nucleic processes?
Can permeate the cell membrane as they are lipid-soluble.
What are cell surface (plasma membrane) receptors?
Receptors on the cell surface.
What are the 4 types of cell surface receptors?
Ionotropic receptors (act as ion channels) Receptors with intrinsic enzyme activity Receptors interacting with JAK kinases G-protein coupled receptors
What do ionotropic cell surface receptors do?
Act as ion channels.
What do receptors with intrinsic enzyme activity do?
Directly initiate enzyme activity.
What do receptors interacting with JAK kinases do?
Bind to JAK kinases which allows phosphorylation and subsequent activation of response.
What do G-protein coupled receptors do?
Messenger binds to receptor which is coupled with a G-protein- the G-protein initiates enzyme regulation.
What are two common enzymes that G-protein coupled receptors can be attached to?
Adenylyl cyclase
Phospholipase C
What does adenylyl cyclase do?
Produces cAMP to regulate PKA.
What does phospholipase C do?
Produces DAG to regulate PKC and IP3 to regulate calcium.
What do PKA and PKC do?
Used to phosphorylate therefore have a host of functions.
What is the largest class of cell surface receptors?
G-protein coupled receptors.
Are there different types of G-protein coupled receptor?
Yes, there are many- Gs, Gi, Go, Gq etc.
What is a drug?
A drug is a chemical agent that affects a biological system.
What are the 4 sources of drugs?
Natural products
Synthetic products
Gene therapy
Biotechnology
How do drugs act?
Act by binding on receptor binding sites and have characteristic responses.
What do agonists do?
Mimic receptor function.
What do antagonists do?
Block receptor function.
What is the EC50?
EC50 is the concentration of the drug that gives a 1/2 maximal response.
What is affinity?
Affinity is determined by the strength of chemical attraction between a drug and its receptor.
What is efficacy?
Efficacy is determined by a drugs ability at actually activating the receptor.
What characterises a full agonist in terms of affinity and efficacy?
Increased affinity, increased efficacy.
What characterises a partial agonist in terms of affinity and efficacy?
Increased affinity, reduced efficacy.
What characterises an antagonist in terms of affinity and efficacy?
Increased affinity, NO efficacy (blocks).
Does one transmitter always act on one receptor?
No- one transmitter may act on several receptor subtypes.
What do selective agonists do?
Only activate some receptors.
Give an example of a selective agonist.
Salbutamol.
What do selective antagonists do?
Only block some receptors.
Give an example of a selective antagonist.
Propanolol.
How is EC50 affected by affinity?
Higher affinity = lower EC50
Lower affinity = higher EC50
