The main function of the peripheral nervous system (PNS) is to connect the central nervous system (CNS) to the rest of the body, such as the organs, muscles and limbs. The PNS is made up of nerves and neurons that connect the nervous system to the various parts of the body, which allows the brain to communicate with all areas of the body. The PNS is made up of two separate divisions known as the somatic nervous system (SNS), which is responsible for controlling the voluntary muscles and sensory organs, and the autonomic nervous system (ANS), which is responsible for controlling the involuntary muscles.
There are two types of neurons within the peripheral nervous system, known as the sensory and motor neurons, and they transfer information via chemical and electrical signaling. The sensory neurons, also known as afferent neurons, are responsible for sending messages from the body to the nervous system. The motor neurons, also known as efferent neurons, send messages from the brain to the various parts of the body. Some of the motor neurons are quite long because they are required to reach from the peripheral nervous system to whatever part of the body they need to communicate with.
The SNS is responsible for communication between the brain and the voluntary muscles and sensory organs. It receives the message from a sensory organ, such as the eyes, ears or skin, and relays it back to the CNS for processing. After the brain receives the signaling, it is then able to make a choice about how it will cause the body to react.
The ANS is responsible for communications between the brain and the involuntary muscles, glands and organs such as the heart, lungs and adrenal glands. The communication in this part of the peripheral nervous system controls the involuntary areas of the body in the unconscious state of mind. In some cases, such as deep breathing, the ANS can also work together with the consciousness.
The autonomic nervous system is further divided into three sections known as the sympathetic nervous system (SNS), the parasympathetic nervous system (PSNS) and the enteric nervous system (ENS). The SNS helps the body deal with stress more effectively by releasing more adrenaline, increasing perspiration and the heart rate. The PSNS, on the other hand, does the opposite, and it helps the body relax and is able to control functions such as slowing the heart rate, constricting the pupils and dilating the blood vessels. The ENS is responsible for taking care of all the digestive functions within the esophagus, stomach and intestines.