Part 3

Question 1

Agonist

Answer 1

Binds to the active site of the receptor and causes a conformational change of the receptor resulting in activation of the receptor which results in cellular response

Question 2

Antagonist

Answer 2

Binds to active site of the receptor but does not cause a conformational change which is necessary for activation
*prevents agonists from binding and activating the receptor

Question 3

Allosteric modulators

Answer 3

Binds to the site on the receptor other than the agonist binding site and thus inhibit or potentiate the receptor response to agonist

Question 4

Competitive antagonism

Answer 4

Agonist occupancy at a given agonist concentration is reduced because the agonist and the antagonist are both binding to the active site. Because the receptor active site can only be bound to one molecule at a time

Question 5

Why is competitive antagonism surmountable

Answer 5

Because the agonist and the antagonist both compete for the same binding site, increasing the concentration of the agonist will restore agonist occupancy and
tissue response

Question 6

What happens to the graph in competitive antagonism

Answer 6

*the slope remains the same
*shape also remains the same
*the curve shifts to the right
*C50 increases
*Emax remains the same

Question 7

How and why does the Emax and C50 remain the same

Answer 7

*the C50 shifts to the right and increases because you need more more of the drug to reach max effect
*Emax remains the same cause you will still reach the same max effect it will just take longer

Question 8

Examples of agonists and antagonists in competitive antagonism

Answer 8

a and b adrenoceptors
Agonists- noradrenaline,isoprenaline
Antagonists-propranolol

Opiod receptors
Agonist-
Morphine
Heroin
Etorphine
Antagonists- naloxone, diprenorphine

Question 9

Analgesic

Answer 9

Relieves pain

Question 10

Irreversible antagonism

Answer 10

When an antagonist binds to the receptor and forms a covalent bond with the receptor or binds so tightly to the receptor that the receptor is no longer available to bind to agonist

Question 11

Effects on C50 and Emax irreversible antagonism

Answer 11

C50 remains same
Emax decreases

Question 12

Phenoxybenzamine

Answer 12

An irreversible a adrenoceptor used to control hypertension caused by catecholaminws released by pheochromocytoma, a tumour in adrenal medulla

Question 13

Allosteric modulator

Answer 13

Non competitive inhibitor that binds to site other than active site and changes affinity of receptor for agonist to inhibit or potentiate it

Question 14

Allosteric activator

Answer 14

Binds to Allosteric site of receptor and potentiate the effect of agonists

Question 15

Benzodiazepines

Answer 15

Allosteric activatorsthat potentiate the effects of aminobutyric acid (GABA) at GABAa receptor

Question 16

Allosteric antagonist

Answer 16

Binds to Allosteric site and inhibits effect of agonist