Pharma Easy Notes @Pharmacy

Classification All membrane-bound receptors belong to one of the three following systems families based on their structure and function. ( LGKI ) L igand-gated ion channels G - Protein-coupled receptor K inase-linked receptors I ntracellular receptors 1. Ligand-gated ion channels Ion channels are protein complexes that traverse the cell membrane and form a tunnel through it. The function of an ion channel is - to allow the flow of ions across the cell membrane and there are specific ion channels for sodium, Potassium, Calcium, and chloride ions. Without ion tunnels, ions could not cross the fatty cell since many enzyme-catalyzed reactions are dependent on ionic concentration. In the resting state, the ion channel is closed and the receptor's binding site is unoccupied . The signal to open the ion channel comes from the chemical messenger which binds to the receptors and causes it to change shape which travels through the entire ion channel. The proteins making up the ion channe

Theories of Receptor Most Therapeutically useful drugs bind only transiently of their intended receptor O (i) O ccupation theory R (ii) R ate theory T (iii) T he induced-fit theory of enzyme-substrate M (iv) M acromolecular perturbation theory A (v) A ctivation - Aggregation theory 1. Occupation theory Proposed by Gaddum and Clark states The intensity of the pharmacological effect is directly proportional to the number of receptors occupied by the drug. The Pharmacological response of a drug molecule is a Function of dose Number of receptors available & Its intrinsic activity The rate of combination drug and receptor can be therefore expressed as