Nervous system – Nervous or neural system is the most important system of an animal and man. It is a system of highly specialized nerve fibers, nerve cells and organs that coordinate and control the activities of different parts of the body. This is done by converting the internal and external stimuli of environmental changes into the form of electrical impulses and transmits them to other specialized cells to react accordingly. The highly specialized cells are called Receptors and Effectors respectively. The main function of the nervous system is to collect information about the external conditions of the internal state of the body to analyze the information and to initiate appropriate responses to satisfy certain needs. The nervous system performs two functions such as coordination and integration.
In Vertebrates it is categorized as
- Central Neural System (CNS) comprising of Brain and Spinal cord
- Peripheral Neural System (PNS) consisting of mainly nerves which are enclosed bundles of long fibers or Axons that connects the CNS to every part of the body.
Neurons – The basic unit of the Neural System is the individual nerve cell called neurons. Neurons is operate by generating electrical signals which move from one part of the cell to another part of the same cell or to neighboring cells. Human neural system has about 100 billion neurons of which mainly occur in the brain.
Central Neural System – The brain and spinal cord together form CNS. They are protected by hard bony coverings, the brain by the Cranium and the spinal cord by the Vertebral Column. Both brain and spinal cord are bathed in Cerebrospinal fluid (CSF). It carries oxygen and nutrients from the blood to the neurons.