Essential Pharmacology

Question 1

Basic functions of receptors

Answer 1

They can detect changes in the environment, stimuli, and turn them into electrical signals and enable an appropriate response.
Intracellular receptors; live inside the cell so can only be activated by lipophilic compounds eg steroid hormones, NO. Used for transcription and cell activity.
Plasma membrane receptors/ionotropic receptors; fast EPSPs/IPSPs. Used for intrinsic enzyme activity, proliferation, differentiation and JAK kinase-protein synthesis.
G-proteins; coupled to phosphilipase C - activates Protein kinase C, releases Ca2+. Coupled to adenyl cyclase increases/decreases cAMP and activates protein kinase A. Coupled to ion channels gives rise to slow EPSPs/IPSPs

Question 2

Receptor

Answer 2

They are transducers (convert physical quantity to electrical signal) that convert different forms of energy into frequency of APs. They turn a signal into a response.

Question 3

Agonist

Answer 3

A substance which initiates a physiological response when combined with a receptor. Mimics normal action.

Question 4

Antagonist

Answer 4

A substance that blocks or dampens a biological response by binding to and blocking a receptor. Blocks normal action.

Question 5

Ec50

Answer 5

The effective concentration producing 50% of the maximum response. A low Ec50 equals a high affinity.

Question 6

Affinity

Answer 6

Affinuty is determined by the strength of chemical attraction between drug and receptor.
Full agonist has a high affinity and efficacy so fully activates the receptor.
Partial agonist has a high affinity and medium efficacy so partially activates.
An antagonist has a high affinity but low efficiacy so there is no activation.

Question 7

Efficacy

Answer 7

Efficacy is determined by how good the drug is at activating the receptor.

Question 8

Describe the transmission of transmembrane signalling

Answer 8

An extracellular signal acts on a receptor causimg an intracellular signal and activation of effector.

Question 9

Sources of intracellular Ca2+

Answer 9

1. Via inositol trisphosphate (IP3)
2. Via stimulated release of Ca2+ from endoplasmic reticulum
3. Extracellular via v.gated or L.gated Ca2+ channels.
4. Inhibition of Ca2+ transport out of cell