The nervous system is the main communication system for the body, as it transmits messages between the brain and the body. It works with the endocrine system to help regulate body processes, and interprets the information it receives.

The nervous system is made up of a network of nerve cells known as neurones, which transmit messages in the form of impulses. It analyses sensory information and decides how to respond.

The brain is the control centre for the nervous system, as it is a complex mass of nerve tissue. It receives stimuli through the nerves and co-ordinates the required responses.

The nervous system itself can be broken down into three smaller systems: the central, peripheral and autonomic systems.

The central nervous system is primarily made up of the brain and spinal cord, and co- ordinates the actions of the body. Impulses are transmitted throughout the body by the brain, causing other organs to act. The brain is protected by the bones of the skull, whilst the spinal cord is protected by the vertebrae.

A connective tissue called the meninges surrounds the central nervous system, and is made up of three layers. The dura mater layer is an outer sheath, whilst the pia mater layer is attached to the surface of the organs. This layer nourishes underlying tissue through its supply of blood vessels. The arachnoid mater layer provides space for the blood vessels and the circulation of cerebrospinal fluid.

Not only does the central nervous system contain neurones, it also has another type of nervous tissue known as neuroglia. Neuroglia cells are a type of connective tissue that supports and nourishes the neurones. They are smaller cells than the neurones and are found in large numbers.

The peripheral nervous system contains all of the nerves which are found outside of the central nervous system, and link it to the rest of the body. There are 31 pairs of spinal nerves and 12 pairs of cranial nerves which govern the impulses from the central nervous system to the skeletal muscles.

The spinal nerves pass out of the spinal cord, and link to the autonomic nervous system. They receive sensory impulses and transmit motor signals throughout the body. The cranial nerves connect directly to the brain and provide a nerve supply to some of the sensory organs as well as the muscles and the skin of the head and neck.

The autonomic nervous system controls the activities of the smooth and cardiac muscles, as well as the glands. Primarily, its role is to maintain homeostasis within the body. The autonomic system deals with the involuntary activities of the body over which there is no conscious control. This includes regulating the functions of vital organs such as the heart, stomach and lungs, as well as the secretion processes of most glands.

The autonomic nervous system has sympathetic and parasympathetic divisions. The sympathetic nervous system is stimulated in times of stress or danger, known as ‘fight or flight’. It causes the heart to beat faster and so increases blood flow, preparing the body for physical activity. Any non-essential activities at this point are inhibited. The parasympathetic system is associated with resting and blood flow is slowed in a process of rest and digest. This system also stimulates the processes of digestion and the absorption of food.

Massage can stimulate or soothe nerve endings depending upon the movement performed. It can help relieve stress, having a positive effect upon the autonomic nervous system.

The Olfactory System

The nose gives us our sense of smell and the olfactory receptors which do this are found at the top of the nasal cavity. These receptors are neurones with cilia projections which come into contact with the airborne particles which have been breathed in and dissolved in mucous. This chemical stimulus is passed to the chemoreceptors of the olfactory cells, which convert the stimulus into nerve impulses which are then transmitted to the brain.

The Endocrine System

The endocrine system is made up of a number of glands that produces and secretes hormones throughout the body. These glands do not have ducts, and so their products pass directly into the blood stream. These hormones help to regulate the activities of the body, and maintain it through times of stress by upholding a constant environment. They also contribute to the reproductive process.

The main functions of the endocrine system include growth, development and reproduction. It also regulates the metabolism, homeostasis, the immune system and the process of apoptosis by which the death and removal of cells is ordered.

Hormones are chemical messengers that regulate cellular activity and co-ordinate various functions in the body. These hormones can either be synthesised from steroids such as the sex hormones and those of the adrenal cortex, or from amino acids such as insulin and oxytocin. Hormones travel through the blood stream and can influence the activity of the organs. Hormonal messages are slower acting than other nervous messages and take years to have full effect.

There are a number of processes which are stimulated by hormones. These include the synthesis of new molecules, changes in the permeability of the plasma membrane, the transportation of substances into or out of cells, changes in the rate of metabolic reactions and the contraction of the cardiac muscle.

Massage may speed up the delivery of hormones to their target organs making this system more efficient. Calming movements may help reduce the levels of stress causing adrenalin, having a beneficial effect upon homeostasis.