Stimulation by the parasympathetic nervous system increases the permeability of the SA node to potassium ions, whereas stimulation by the sympathetic nervous system decreases the permeability of the SA node to this same ion.

Question

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Stimulation by the parasympathetic nervous system increases the permeability of the SA node to potassium ions, which slows down the heart rate. In contrast, stimulation by the sympathetic nervous system increases the permeability of the SA node to calcium and sodium ions, which speeds up the heart rate, not decreasing potassium ion permeability.

Stimulation by the Parasympathetic Nervous System Increases the Permeability of the SA