TYPES OF NERVE CELLS / NEURONS

  

            1. SENSORY NEURON    : Sensory neurons conduct impulses from three types organs to the brain and the spinal cord. 

   

          2. Motor Neurons           :  Motor neurons conduct impulses from the of spinal cord to effector organs like muscles or glands .

        3. Association neurons   : Association neurons perform the function in the nervous system 

              The human nervous  system 

             The human system is devided into the following three parts. 

1. Central nervous system .

2. Peripheral nervous system.

3. Autonomic nervous system.

 

Central Nervous System or CNS

    

   

                        The central nervous system consists of the brain and spinal cord .

 The organization of the nervous system and it is safely located in the cranial cavity.

The spinal cord is protected by the vertebral column. In the space layers called the meninges.  
cavities present in various part of the brain are called ventricles whereas the long tuvbular cavity of the spinal cord is called the central canal. The ventricles, central canal and spaces between the meninges are filled with cerebro-spinal fluid. This fluid supplies nutrients to the central nervous system and protects it from shock. 

   

         The brain of an adult human weight 1300-1400 grams and consists of approximately 100 billion  neurons.

 

          The left side of body our brain controls the right side of our body and right side of our brain controls left side of the body. In addition,  the left  side of the brain  controls our  speech  and conversation,  writing,  logical  thinking etc. Whereas the right side controls artists abilities. 

  

Cerebrum:

         This is largest part of our brain and consist of two cerebral hemispheres. Thise hemispheres are joined with each other with the help of tough fibers and nerve tracts . The cerebrum occupies two - thirds of the brain . Hence, it is also called convolutions. Convolution increases the surface area of the cerebrum and therefore a large  number  of nerve cells   can be accommodated. 

    

     

Cerebellum:

           The is the smaller  part  of the brain situated below the cerebrum at the back othe cranial cavity.  Its surface shows shallow  grooves instead of deep convolutions. 

Medulla oblongata:

                       This  is the hind - most part of brain . There are two triangular swollen structure called pyramids on the upper side of medulla oblongata. The medulla oblongata continues download as the spinal cord.