Human Nervous System

Systems that allow communication between the receptors and the effectors of the body so that correct reactions to any change in the environment can be brought about

Responds the fastest and is brought about by impulses travelling along nerves

Is slower and is brought about by chemicals called hormones which are carried in the blood

Is the body’s control and communication centre. It provides information between the environment, the brain and the different parts of the body. This enables the body to function in an orderly and effective way and to perform all the everyday tasks

• Sensory function: sensory receptors detect the changes in the external environment and the environment within the organism • Integrative function: the central nervous system receives info and ‘decides’ which effectors need to reset to the stimulus • Motor function: effectors (muscles and glands) bring about appropriate responses

Stimuli are physical and chemical changes in the environment, both interns, and external, that cause a response in an organism. We live in an environment that is constantly changing so we are constantly exposed to stimuli. The following change: - light, temperature, sounds, atmospheric pressure Inside our bodies conditions are also changing: - blood pressure, blood pH, tension in muscles etc.

The central nervous system is made up of a concentrated mass of interconnected neurons (nerve cells), grouped together to form the brain and spinal cord

• the extremely soft and delicate tissue of the bran and spinal cord are protected by three connective tissue membranes called meninges • the space between the 2nd and 3rd layer of membranes is filled with cerebrospinal fluid which acts as a cushion, protecting the CNS against shock and damage. (Cerebrospinal fluid is a fluid formed from blood plasma in special areas in the walls of the ventricles) • the whole CNS and it’s meninges are enclosed within a bony case made up of two separate structures: 1. The cranium, a strong, dome-shaped structure that protects the brain against mechanical injuries, made up of 8 curved skull homes immovably dove-tailed together by fibrous joints called sutures. 2. The vertebral column, made up of thirty three, irregular shaped vertebrae, surrounds the spinal cord and protects it against mechanical injury.