What effect does the sympathetic branch have on the fetal heart rate?

What effect does the sympathetic branch have on the fetal heart rate?

• A. Decreases heart rate
• B. Increases heart rate
• C. Reduces heart rate variability
• D. Slows fetal breathing

Answer: (B)

The sympathetic nervous system increases fetal heart rate. It does this by releasing norepinephrine onto beta-adrenergic receptors in the fetal heart, which speeds up the pacemaker activity of the SA node and enhances conduction. This chronotropic effect raises the heart rate to help boost cardiac output and oxygen delivery during stress or hypoxia. Parasympathetic activity, in contrast, would slow the heart rate, and other options like reducing heart rate variability or slowing fetal breathing aren’t the direct primary effects of sympathetic stimulation on heart rate.

The sympathetic nervous system increases fetal heart rate. It does this by releasing norepinephrine onto beta-adrenergic receptors in the fetal heart, which speeds up the pacemaker activity of the SA node and enhances conduction. This chronotropic effect raises the heart rate to help boost cardiac output and oxygen delivery during stress or hypoxia. Parasympathetic activity, in contrast, would slow the heart rate, and other options like reducing heart rate variability or slowing fetal breathing aren’t the direct primary effects of sympathetic stimulation on heart rate.