Question

What would happen to the SA node if a chemical blocker was used to reduce transport of Na+ into the pacemaker cells? What would happen to the SA node if a chemical blocker was used to reduce transport of Na+ into the pacemaker cells? There will be no change. The SA node would depolarize more slowly, increasing the heart rate. The SA node would depolarize more slowly, reducing the heart rate. The SA node would depolarize more quickly, increasing the heart rate. The SA node would depolarize more quickly, decreasing the heart rate.

Answer 1

1. The SA node will depolarize more slowly , reducing heart rate

• SA node is pacemaker of heart. It decides heart rate. When it depolarize faster then it increases heart rate. When it depolarize more slowly then heart rate decreases.
• Sodium cnahhel are important for depolarization of SA node (like any other excitable tissue). Thus blockage of sodium transport will lead to slow depolarization and decreased heart rate.