The Bainbridge reflex is an atrial reflex that does what in response to increased venous return?

The Bainbridge reflex is an atrial reflex that does what in response to increased venous return?

• A. Increases heart rate in response to increased venous return.
• B. Decreases heart rate in response to increased venous return.
• C. Increases stroke volume in response to increased afterload.
• D. Reduces heart rate in response to low blood pressure.

Answer: (A)

The Bainbridge reflex is an atrial stretch reflex that increases heart rate when venous return rises. When more blood returns to the heart, the walls of the right atrium stretch. This stretch is picked up by atrial receptors and signals the nervous system to boost heart rate by increasing SA node firing (via increased sympathetic tone and reduced parasympathetic influence). The goal is to match the higher venous return with a faster heart rate so cardiac output can keep pace with the incoming blood. This is why increased venous return leads to tachycardia. It’s not about increasing stroke volume in response to afterload, nor about decreasing heart rate or responding to low blood pressure.

The Bainbridge reflex is an atrial stretch reflex that increases heart rate when venous return rises. When more blood returns to the heart, the walls of the right atrium stretch. This stretch is picked up by atrial receptors and signals the nervous system to boost heart rate by increasing SA node firing (via increased sympathetic tone and reduced parasympathetic influence). The goal is to match the higher venous return with a faster heart rate so cardiac output can keep pace with the incoming blood. This is why increased venous return leads to tachycardia. It’s not about increasing stroke volume in response to afterload, nor about decreasing heart rate or responding to low blood pressure.