Question

The “Plateau Phase” during the cardiac action potential is caused by: A. opening of Na+ channels...

The “Plateau Phase” during the cardiac action potential is caused by:

A. opening of Na+ channels

B. opening of K+ channels

C. opening of Ca+2 channels

D. opening of Cl- channels

E. closing of K+ channels

Science   Anatomy-And-Physiology   
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Answer #1

Ans:-

C,

Opening of the Ca+2 channels.

The " Plateau phase" during the cardiac action potential is caused by the opening of the Ca+2 channels.

Cardiac action potential:- It is a brief change in the voltage across the cell membrane of the heart cells.

It has five phases:-

Phase 0 or upstroke or rapid depolarisation,

Phase 1 or early rapid repolarisation,

Phase 2 or plateau phase,

Phase 3 or final rapid repolarisation,

And

Phase 4 or resting membrane potential and diastolic deplorization.

Rest of the given options are wrong because:-

- opening of the Na+ channels occurs during phase 0.

- opening of the K+ channels occurs during phase 2 and 3rd phase.

- opening of the Cl- channels occurs during phase 1.

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