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CBSE Class 11-science Answered

A: elevated levels of sodium Ion increase the heart rate and contact ility R: elevated sodium Ion level increase excitability of s a node
Asked by arushidabhade | 25 Aug, 2019, 02:57: PM
Expert Answer

Decreased sodium lowers blood volume, causing the blood pressure to drop and the heart rate to increase. Therefore, assertion (A) is not true.

The pacemaker potential is produced by a decrease in membrane permeability to potassium, a slow inward current because of calcium influx via T-type (transient) calcium channels, and an increased sodium current because of sodium–calcium exchange. Therefore, reason (R) is true.

Answered by Sheetal Kolte | 26 Aug, 2019, 11:56: AM

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