ABSTRACT
The nervous system shows many more specialized features compared to any other organ. This elaborate system contains complicated anatomical and functional structures and exhibits several unique metabolic processes. The signs of disorder in neurological functions also show variations according to the anatomic level of the nervous system involved. The incidence of Down’s disease is influenced by environmental and genetic factors which increase the occurence of nondisjunction and trisomy. The study of narcosis and excitation provides an initial tool when we evaluate various disease processes of the nervous system. Excitation in the central nervous system is associated with events leading to the firing of the neurons and generation of action potentials. Lesions of the nerves are associated with characteristic degenerative changes of injured nerve cells. These changes are primary or secondary, depending on the initial integrity of the axon and its interaction with the myelin sheath and the Schwann cell.
