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: The Bainbridge reflex (also called the atrial reflex) is a compensatory cardiac reflex triggered by a rise in right atrial pressure.
Step 2: When the large systemic veins and the right atrium are distended by increased venous return or blood volume, stretch receptors in the atrial walls fire and signal the medulla.
Step 3: Through a positive feedback mechanism, this leads to a compensatory increase in heart rate, helping the heart pump out the extra returning blood and prevent venous pooling. So the correct answer is increased heart rate (option d).
Step 4: Bradycardia (a) is the opposite effect and is seen with the baroreceptor reflex, not the Bainbridge reflex. Increased cardiac output (b) may follow but is a downstream result, not the primary reflex response. Decreased venous return (c) is the trigger's opposite, since the reflex is set off by increased venous return.