Receptor Reserve — FRCA Primary MCQ

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HardPharmacology - General PrinciplesReceptor ReserveFRCA Primary

Regarding the concept of receptor spare or receptor reserve which statement is correct?

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Correct answer: B — A maximal response can be achieved without occupying all available receptors

In systems with receptor reserve a maximal response can be achieved by occupying only a fraction of the total receptor population. The remaining unoccupied receptors are 'spare'. This means the system has a high receptor density relative to the number needed for maximal effect. It increases sensitivity (low EC50) without changing efficacy (Emax).

Reference: Peck Hill Williams 2014 Pharmacology for Anaesthesia and Intensive Care