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Year 1 Medicine > Receptors > Flashcards

Flashcards in Receptors Deck (18):

Why does a chemical messenger only fit one receptor?

So it only produces a response in cells with that receptor, allowing specificity and so not all cells do the same.


Give an example of a lipid soluble chemical messenger?

Steroid hormones
Nitrogen oxide.


What are intracellular receptors?

Receptors located inside the cell rather than on its cell membrane


What are the 4 different types of plasma membrane receptor?

Receptor that functions as an enzyme
Receptor that directly alters an enzymes activity
G-protein coupled receptors.


What is an ionotropic receptor?

A membrane receptor that is also an ion channel. Fast EPSPs and fast IPSPs.


Give an example of a receptor with intrinsic enzyme activity?

Receptor tyrosine kinases-proliferation & differentiation


Give some examples of g-coupled proteins?

Coupled to to adenylyl cyclase -
increases (or decreases) cAMP = 2nd messengers
activates (or inhibits) PKA.

Coupled to phospholipase C -
produces diacylglycerol and inositol trisphosphate
activates PKC and releases Ca2+ from internal stores.

Coupled directly to ion channels -
evoke slow EPSPs and slow IPSPs


What is pharmacology?

The study of the way living systems are affected by chemical agents


What is a drug?

Any chemical agent that affects a biological system


What happens when the concentration of drug is increased?

A bigger response is achieved as more receptor sites are filled. This only lasts up until a point as eventually all receptor sites will be used up so increasing drug conc won't have any effect.


What is affinity?

Determined by strength of chemical attraction between drug and receptor.


What is efficacy?

Determined by how good the drug is at activating the receptor.


What are agonists?

Chemicals that mimic the normal effect of the receptor.


What are antagonists?

Chemicals that block the normal action of the receptor.


Give some examples of endogenous agonists?

Acetylcholine - master key for all cholinergic receptors, nicotinic and muscarinic.

Noradrenaline – which activates all adrenergic receptors alpha-1, alpha-2, beta-1, beta-2.


What is a selective agonist?

Only mimics and activates some of the chemicals acting on the receptors. E.g salbutamol - beta-2 agonist.


What is a selective antagonist?

Only inhibits some of the receptors. E.g propranolol - a beta 1 and beat 2 antagonist.


What do alpha 1, alpha 2, beta 1, and beta 2 do?

Alpha 1 - Dilates pupil
Alpha 2 - Inhibits gastric secretion
Beta 1- Increases heart rate
Beta 2- Dilates airways