This document discusses different types of receptors including ion channel receptors, G protein-coupled receptors, kinase linked receptors, and intracellular receptors. It defines key concepts such as receptor, affinity, intrinsic activity, and defines different types of ligands including agonists, antagonists, and partial agonists. It also discusses receptor mechanisms, types of G proteins, desensitization, up-regulation, down-regulation, spare receptors, and some receptor-related diseases.

2. Receptor :
Protein macromolecules on cell surface or cytoplasm
Affinity :
Capability of drug to bind to receptor
Intrinsic activity :
Ability of drug to elicit response after binding to
receptor

3. Agonist
High affinity and high IA
Antagonist
High affinity and IA absent
Partial agonist
High affinity and low IA
Inverse agonist
Produce effect opposite to agonist

4. 1. Ion channel receptor
2. G- protein coupled receptor (Metabotropic)
3. Kinase linked receptor
4. Intra cellular receptors

5. Present on cell membrane
Coupled to an ion channel
Open when receptor occupied by agonist
Eg : Benzodiazepine

6. Receptor bound to effector system through GTP binding
protein
G protein- α,β, Subunits
Effector mechanisms
Adenylate cyclase
Phospholipase C
Ion channel
Types- Gs, Gi
Eg. Adrenergic drugs

7. Receptor directly linked to tyrosine kinase
Autophosphorylation
Eg, Insulin

8. Located in cytoplasm
Alteration in gene transcription
Eg : steroid hormone

9. Desentisation
After reaching high level response decreases over time
Reversible
Up regulation
Prolonged exposure to high concentration of agonist
causes reduction in number of receptors
Down regulation
Prolonged exposure to high concentration of antagonist
causes increase in number of receptors

10. Spare receptors
Unoccupied receptors serving as reserve
Receptor related diseases
Diabetes
Myasthenia gravis
Familial hypercholesterolemia