Receptors

Question 1

Why does a chemical messenger only fit one receptor?

Answer 1

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

Question 2

Give an example of a lipid soluble chemical messenger?

Answer 2

Steroid hormones

Nitrogen oxide.

Question 3

What are intracellular receptors?

Answer 3

Receptors located inside the cell rather than on its cell membrane

Question 4

What are the 4 different types of plasma membrane receptor?

Answer 4

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

Question 5

What is an ionotropic receptor?

Answer 5

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

Question 6

Give an example of a receptor with intrinsic enzyme activity?

Answer 6

Receptor tyrosine kinases-proliferation & differentiation

Question 7

Give some examples of g-coupled proteins?

Answer 7

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

Question 8

What is pharmacology?

Answer 8

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

Question 9

What is a drug?

Answer 9

Any chemical agent that affects a biological system

Question 10

What happens when the concentration of drug is increased?

Answer 10

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.

Question 11

What is affinity?

Answer 11

Determined by strength of chemical attraction between drug and receptor.

Question 12

What is efficacy?

Answer 12

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

Question 13

What are agonists?

Answer 13

Chemicals that mimic the normal effect of the receptor.

Question 14

What are antagonists?

Answer 14

Chemicals that block the normal action of the receptor.

Question 15

Give some examples of endogenous agonists?

Answer 15

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

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

Question 16

What is a selective agonist?

Answer 16

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

Question 17

What is a selective antagonist?

Answer 17

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

Question 18

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

Answer 18

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