Which among the following statement regarding skeletal and cardiac muscle is false

A. Both require calcium for excitation contraction coupling

B. The excitation contraction coupling of skeletal muscle is independent of extracellular calcium

C. Both have graded contraction

D. Plateau phase is seen in action potential of cardiac muscle. (Repeat, 09)

Correct Answer: Both have graded contraction

Description: Ans: c (Both have graded contraction) Ref: Ganong 22nd ed/p.79Cardiac action potentialAction potential can be defined as the sequence of changes in the membrane potential in an excitable cell due to opening and closure of differention channels after application of a threshold stimulus.Phases of action potentialPhase 0 - Opening of voltage gated Na channel.Phase 1 - closure of sodium chan-nel- leads to initial rapid depolarization.Phase 2 - plateau phase- due to opening of L type Ca2+channels.Phase 3 - final repolarization due to closure of Ca2+ channels & K+ efflux.Phase 4 - resting membrane potential.

Category: Physiology

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