Accelerator nerve

Accelerator Nerve

Diagram of the human heart, with the accelerator nerve highlighted.

The accelerator nerve or cardiac accelerator nerve is a component of the autonomic nervous system that directly influences heart rate and force of contraction. It is a branch of the sympathetic nervous system and plays a crucial role in the body's fight-or-flight response.

Structure

The accelerator nerve originates from the thoracic spinal cord, specifically the first five thoracic segments (T1-T5). It travels through the sympathetic trunk to reach the cardiac plexus, where it synapses with postganglionic neurons. These neurons then extend to the sinoatrial node and atrioventricular node, the heart's natural pacemakers.

Function

The accelerator nerve increases heart rate (chronotropy) and the force of heart contractions (inotropy) in response to stress or exercise. It does this by releasing the neurotransmitter norepinephrine, which binds to beta-1 adrenergic receptors on cardiac cells, leading to an increase in calcium influx and thus increased contractility and heart rate.

Clinical significance

Abnormalities in the function of the accelerator nerve can lead to conditions such as tachycardia, bradycardia, or arrhythmia. Understanding the role of the accelerator nerve is also important in the management of conditions like heart failure and hypertension.

See also

• Cardiac plexus
• Sympathetic nervous system
• Autonomic nervous system
• Sinoatrial node
• Atrioventricular node