The nervous system, together with the endocrine system it(he,she) integrates(repays) and controls the numerous functions that allow that the animal should regulate his(her,your) internal environment and reacts to his(her,your) external environment or faces it. The functional unit of the nervous system is the "neuron", which consists of a cellular body that contains the core(nucleus), the metabolic machinery, in dendritas to receive stimuli, and in an axón that broadcasts stimuli to other cells.

The nervous system divides in two parts(reports): the nervous central system and the nervous peripheral system.

It is constituted by the spinal marrow and the encephalon.


The spinal marrow:
It is a white brilliant cord that parts with the base of the encephalon and crosses the vertebral column, in the low prolongation of the rachidial bulb, measures approximately 45 to 50 cms of length and weight between(among) 26 and 30 gr., it(she) is lodged inside the vertebral conduit that the vertebrae and certain ligaments form(train).


The encephalon:
It is the extensive portion that is situated over the spinal marrow, is contained in the cranial cavity and joins the spinal marrow level of the first cervical vertebra, weighs approximately 1400 grams, and has the consistency of a semisoft(semismooth) cheese. The encephalon receives nervous impulses proceeding from the spinal marrow and from the cranial nerves that go directly towards him(it) from the eyes, the internal ear(hearing), or other sites(places) of the body.


Though the knowledge of the structure and function of the encephalon increase rapidly, many people think that it(he,she) was never managing to understand everything. Nevertheless, his(her,your) functions are essential, not only for the integration and control of a multitude of physiological activities that happen in the whole body. Also for the processes that we identify as mind, conscience, perception and interpretation of the information from the external environment, thought, memory(report) and the variety of evasions(escapes) that characterize the human experience. The association of a stimulus with other one with the memory(report) and the coordinated action(share) of the body necessary for a suitable irritability, they depend on the circuits that follow(continue) the nervous impulses in the brain.


In the functional thing, the nervous system differs from the endocrine one in his(her,your) aptitude to answer rapidly, so(then) the nervous impulse can cross the whole organism(organisation) concerning milliseconds. The hormones, on the other hand, move to a minor speed (by means of the blood torrent) and it(he) is typical that provoke slower but lasting answers.