During inspiration, heart rate tends to...

• A. Decrease
• B. Increase
• C. Stay the same
• D. Fluctuate unpredictably

Answer: (B)

Breathing influences heart rate through respiratory sinus arrhythmia, a normal variation where heart rate rises slightly during inspiration. The drop in intrathoracic pressure with inhalation increases venous return to the right atrium, nudging the heart to beat a bit faster to handle the greater inflow. At the same time, there’s a brief decrease in parasympathetic (vagal) influence, which lets the heart rate climb. During exhalation, the opposite shifts occur and the heart rate tends to slow. In healthy individuals, the change is small, but the overall trend during inspiration is an increase in heart rate.