Question

Bainbridge reflex causes?

• A. Bradycardia
• B. Increased cardiac output
• C. Decreased venous return
• D. Increased heart rate

Hint:

It is the atrial stretch reflex that speeds the heart when right atrial pressure rises.

Answer 1

The Correct Option is D

Step 1: Picture a sudden surge of blood returning to the right side of the heart. This stretches the right atrium and the great veins emptying into it.
Step 2: Specialised stretch receptors sitting in the right atrial wall sense this distension and send afferent signals up the vagus nerve to the cardiovascular centre in the medulla.
Step 3: The body answers with the atrial (Bainbridge) reflex, a positive feedback loop that speeds the heart up so the incoming volume is cleared quickly. The result is a faster heart rate.
Step 4: Slowing of the heart (bradycardia) belongs to the baroreflex, which reacts to high arterial pressure, not atrial stretch. A drop in venous return is actually the stimulus running backwards, and a rise in cardiac output is a knock-on effect rather than the reflex itself.
Hence the heart rate goes up. \[\boxed{\text{Increased heart rate}}\]