Autonomic nervous system is the neural control system of the body that regulates the involuntary movements of the body and keeps the regular bodily functions going. Heart rate, digestion, response of pupils to light, respiratory rate, urination, sexual arousal, etc are some such movements controlled by autonomic nervous system. The system is also the primary mechanism that comes into action during a typical stressful situation and works on the fight-or-flight response.
The autonomic nerve pathway involves two nerve cells, connected by many nerve fibers located in a cluster of nerve cells called autonomic ganglion. The nerve fibers originating from the ganglia are connected to the internal organs.
Autonomic nervous system has two main divisions: Sympathetic and Parasympathetic.
Functions of the autonomic nervous system:
Autonomic nervous system controls various internal organs to control the following.
Sympathetic division prepares the body for stressful situations, or fight or flight response by –
Parasympathetic division works to inhibit or control certain actions to conserve and restore the functioning.
Neurotransmitters as messengers:
Chemicals that act as messengers are released in the junction of to nerve fibers where they pass on the information from one nerve cell to another. These are called neurotransmitters. The two important neurotransmitters of the autonomic nervous system are Acetylcholine and Norepinephrine.
Acetylcholine sends signals to other cells such as neurons, muscle cells and gland cells. Adrenaline, also known as epinephrine, helps in regulating visceral functions. Adrenaline is normally produced by adrenal glands and also by a small number of neurons in the medulla oblongata.