Autonomic Nervous System

Your body’s autonomic nervous system is what keeps your internal organs ticking over. It’s responsible for keeping your heart beating, for making you breathe in and out, and for making sure your intestines continue to digest food, while you sleep. Your autonomic nervous system also monitors your body temperature, and automatically produces sweat to cool you down if your body is overheating, or makes you shiver if you are cold, so that the activity of your muscles will generate warmth. You won’t usually be aware of any of this, because the autonomic nervous system operates at a subconscious level. It is made up of the sympathetic, parasympathetic and enteric nervous systems.

1. Sympathetic. This system connects all the internal organs to the brain via the nerves in the spine. When you experience stress, it increases your heart rate, and sends more blood to the muscles, so that you’re ready for ‘fight or flight’. It also responds by sending less blood to the skin, so that you would bleed less if you were injured.

2. Parasympathetic. This system is primarily responsible for preserving ‘homeostasis’, in other words, maintaining a regulated, stable state within your body. It is made up of cranial and lower spinal nerves, and can increase digestive secretions and slow down the heartbeat, as well as sending feedback on the condition of your internal organs to the central nervous system.

3. Enteric. This network of nerves is embedded in the walls of the stomach and intestines, and manages the digestive process by controlling digestive secretions and movement.

Although much of the activity carried out by these networks of nerves is unconscious, it is not completely automated. For example, although you are to some extent on ‘automatic pilot’ when you breathe in and out, you still have a ‘manual override function’, and you can still control your breathing yourself, to sniff a flower, or to sing.