L7- Partial Agonists

Question 1

Describe affinity and efficacy in agonists, antagonists and partial agonists

Answer 1

agonists have both

partial agonists have affinity and some efficacy

Antagonists have affinity but no efficacy

Question 2

What is tone?

Answer 2

Tone is basal activity brought about by an ongoing and underlying release of neurotransmitters for example

Question 3

What do antagonists do to tone?

Answer 3

Competitive antagonists are able to antagonise endogenous mediators and redice the apparent response

Question 4

What’s a non-competitive antagonist?

Answer 4

Binds to another site than the agonist,

Reduces maximum effect

Not affected by agonist concentration

Question 5

WHat are functional antagonists?

Answer 5

Physiological antagonists. 2 agonists that have opposite effects but don’t work on the same receptor. the total effect is usually the sum of the 2 activities

Question 6

What do salbutamol and methacholine do to bronchial airways?

Answer 6

Salbutamol- dilates airways

Methacholine- constricts airways

They are functional anatagonist

Question 7

What constricts and dilates pupils?

Answer 7

Pilocarpine- constricts. (mAChR agonist)

Phenylephrine dilates (adrenoceptor agonist)

Question 8

What’s an indirect antagonist?

Answer 8

Agonist releases chemical from one cell type which acts on a second cell type. Antagonist prevents the effect of the released chemical on the 2nd cell type.

Question 9

Describe how propranolol is an indirect antagonist of nicotine?

Answer 9

If we give an animal nicotine, bind to nicotinic receptors- fires APs which cause release of noradrenaline.

Propranolol can stop the effect of noradrenaline as it is a competitive antagonist of beta adrenoceptors