What is the Autonomic Nervous System?

3rd March 2022 | Dr Melanie Dani

What does the Autonomic Nervous System do?

The autonomic nervous system is the part of the body that controls vital functions such as heartbeat, blood pressure, bowels and bladder, temperature control, and sweating. These are involuntary processes – that is, we don’t have to think about them, because they happen automatically. There are two parts of the autonomic nervous system, the sympathetic and parasympathetic arms.  The sympathetic component coordinates a ‘fight or flight’ response to a possible threat, like running away from an attacker. The ‘parasympathetic nervous system’ coordinates a ‘rest and digest’ response required for us to rest, repair, digest our food and expel waste products.

Many bodily functions are controlled by the autonomic nervous system. These include the heart, lungs, bladder, gut, muscles, skin and even the pupils in your eyes!

How does it work?

One of the main players in the parasympathetic nervous system is the vagus nerve (also known as the 10th cranial nerve). This nerve arises in the control system of the brain and travels down the neck, where it sends and receives nerve endings (which send and receive signals) to the chest and abdomen. It exerts a major influence on the heart, and the way it beats, but also sends signals from the heart back to the brain, informing the brain about the condition of the heart and body. This image shows the major vagal nerve supply to the oesophagus (gullet) and heart.

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