What is regulated by the autonomic nervous system through the cardiac Sinoatrial node?

What is regulated by the autonomic nervous system through the cardiac Sinoatrial node?

• A. Pulse
• B. Blood pressure
• C. Respiratory rate
• D. Temperature

Answer: (A)

The autonomic nervous system regulates heart rate by acting on the sinoatrial node, the heart’s natural pacemaker. Sympathetic input increases the rate at which SA node cells fire, speeding up the heart and raising the pulse. Parasympathetic input slows that firing rate, lowering the pulse. Respiratory rate is controlled by brainstem centers, temperature by the hypothalamus, and blood pressure involves multiple factors including vascular tone and cardiac output, but the specific effect through the SA node is on heart rate, i.e., the pulse.

The autonomic nervous system regulates heart rate by acting on the sinoatrial node, the heart’s natural pacemaker. Sympathetic input increases the rate at which SA node cells fire, speeding up the heart and raising the pulse. Parasympathetic input slows that firing rate, lowering the pulse. Respiratory rate is controlled by brainstem centers, temperature by the hypothalamus, and blood pressure involves multiple factors including vascular tone and cardiac output, but the specific effect through the SA node is on heart rate, i.e., the pulse.