Your Heart Has Its Own Little Brain

The heart is not just a pump taking orders from above. Embedded in its walls is the intrinsic cardiac nervous system, a web of neurons and ganglia so capable that researchers call it the heart’s “little brain.”

This network contains all three working classes of nerve cell: sensory (afferent) neurons that detect stretch and chemistry, motor (efferent) neurons that nudge rate and contraction, and interneurons that wire the local circuit together. Because it carries sensors, processors, and effectors, the heart can run reflexes and fine-tune its own output locally, without waiting for the brain.

A network of intrinsic neurones spread widely over the cardiac chambers gives rise to the idea of a “little brain.”

The scale is real. One detailed map of the rabbit heart counted more than 2,200 neurons across six clusters, and counts climb to roughly 700 ganglia in humans. This autonomy helps explain how a transplanted heart, severed from its original nerves, can still keep beating and regulating itself.