The Nervous System

The human nervous system is a complex network of nerve cells that carry messages to and from the brain and spinal cord from different parts of the body and so helps all the parts of the body to communicate with each other.

The human nervous system is divided into the central nervous system and the peripheral nervous system. Each of these are further divided into different components, each with a different function but all working together. 

Nervous System =  Central NS + Peripheral NS

Central Nervous System =  Brain + Spinal Cord

Peripheral Nervous System =  Somatic NS + Autonomic NS

Autonomic Nervous system =  Sympathetic NS + Parasympathetic NS

The nervous system has two main functions:

• To collect, process and respond to information in the environment.
• To co-ordinate the working of different organs and cells in the body.

The central nervous system is made up of the brain and spinal cord. It controls behaviour and maintains the regulation of the body's physiological processes.

The Spinal Cord

The main function of the spinal cord is to relay informtion between the brain and the rest of the body. This allows the brain to monitor and regulate body processes, such as breathing.

The spinal cord is connected to different parts of the body by pairs of spinal nerves. 

The spinal cord also allows us to perform simple reflexes without the direct involvement of the brain.

Brain

The brain is the centre of all conciousness.  It is divided into two hemispheres.

The brain can also be divided into 4 main areas - the cerebrum, cerebellum, diencephalon and brain stem.

The function of the PNS is to relay nerve impulses from the CNS to the rest of the body and from the body back to the CNS. There are two main divisions of the PNS, the somatic NS and the autonomic NS. 

The somatic nervous system

It's function is to control muscle movements and recieve information from sensory receptors.

The Autonomic nervous system 

It governs vital functions within the body such as breathing, heart rate, digestion, sexaul arousal and stress responses. (unconscious processes).

The sympathetic nervous system

The SNS is primaraly involved in responses that help us to deal with emergencies such as increasing heart rate and blood pressure.

Neurons from the SNS travel to vitually every organ and gland and prepares the body for rapid action necessary when the individual is under threat. 

It slows body processes that are less important in emergencies such as digestion. 

The Autonomic nervous system 

It governs vital functions within the body such as breathing, heart rate, digestion, sexaul arousal and stress responses. (unconscious processes).

The sympathetic nervous system

The SNS is primaraly involved in responses that help us to deal with emergencies such as increasing heart rate and blood pressure.

Neurons from the SNS travel to vitually every organ and gland and prepares the body for rapid action necessary when the individual is under threat. 

It slows body processes that are less important in emergencies such as digestion. 

The parasympathetic nervous system 

The PNS is the opposite to the SNS, it relaxes the body after the emergency has passed. 

The PNS slows the heartbeat down and reduces blood pressure. Also digestion begins again under PNS influence.