Written by: Liz Paton, MSc
Autonomic Nervous System Overview
The autonomic system controls involuntary bodily functions such as breathing, digestion, heart rate and blood pressure. It is part of the peripheral nervous system which helps to control nerves outside of the brain and spinal cord. Neurons send signals to various organs, which helps maintain balance in the body, known as homeostasis.
Autonomic System Anatomy
Two neurons (nerve cells) are required for an autonomic nerve pathway. The brain and spinal cord contain one neuron. The second neuron is surrounded by other neurons, forming an autonomic ganglion, and the two neurons connect via nerve fibres. The nerve fibres from the ganglia then connect to various organs.
A reflex action is a rapid involuntary response and involves different types of neurons. A reflex arc is a nervous pathway that is involved in reflex actions. The autonomic nervous system consists of many reflex actions, known as autonomic reflexes, which are involuntary and help to keep the body regulated.
Autonomic System Function
The autonomic system has three main divisions, the sympathetic nervous system, the parasympathetic nervous system and the enteric nervous system. The sympathetic nervous system and the parasympathetic nervous system work in opposition to each other
The sympathetic nervous system is our “fight or flight” response; this reaction occurs when we are put in a dangerous situation. A few examples of what happens in the body during this response include increased heart rate, dilated pupils and increased blood flow to the muscles.
The parasympathetic nervous system is our “rest and digest response”. This system works to calm the body and promote digestion. Some examples of what happens in the body include increased blood flow to the digestive system, decreased heart rate, and saliva secretion.
The enteric nervous system is a nervous system within the digestive system. This nervous system helps with chemical and mechanical changes and helps with the regulation of secretions in the digestive system.
Pair up this guide with our Autonomic Nervous System Anatomy Revision Worksheets for the best revision session.