THE NERVOUS SYSTEM.
The nerves of the human body are not unlike the vast telegraph system of this continent.
The millions of nerve filaments are similar to the network of wires that keep all the cities in close sympathy and communion. The nerves have to deal with organs instead of villages, and with cells in place of individuals.
Commerce is regulated and train loads of food supplies dispatched here and there by telegraph, while in the body the nerves send their analogue, increased blood and nourishment, where it is required.
The various organs of sense receive manifold impressions of conditions to be met, food required and dangers to be avoided and the nerves transmit these impressions telegraphically to the brain.
The structure of the brain, spinal cord and sympathetic nerves, is not unlike a gigantic and complicated galvanic battery. The number of cells in the brain and spine are more numerous, by many millions, than those supplying any telegraph system.
As the blood supplies each cell with its necessary nourishment and removes its used up or waste materials, so does the workman give each cell of his battery fresh chemicals from time to time, and removes the used up waste.
The wires that lead from this battery to every part of the country are like the nerve filaments that go to each part of the human body and make them all—no matter how minute—perform their functions in a proper manner, and, when done, permit them to retire to rest.
With the complicated human structure, when disease takes hold, we have the same troubles that would be presented were the telegraph operators suddenly to become ill. What confusion and discord would prevail! If the sickness is severe enough to cause delirium, it would be as though madmen were at the telegraph keys dispatching trains of passenger cars which could hardly fail to bring injury and destruction to unwary travelers.
In health, we are unaware of the work of the nerves. The wheels of life move without noise. Few realize that the cavities of the heart (auricles and ventricles) are contracting steadily and alternately under the guidance of nerve cells. By this means the stream of blood, laden with nourishment, is sent to every part of the body.
Silently the stomach pours out, under nerve influence, its juices that dissolve and change parts of the food, that it may pass into the blood in condition to nourish. In a similar way, the pancreas pours out a fluid that digests the fats.
The muscular fibres of the intestines are caused to contract rhythmically and force along the bolus of digested food, so that its soluble parts may be taken up by the minute absorbent vessels to enrich the blood.
All these things of most vital importance we know least about. They go on, from day to day, without our being aware of the work done.
Let something interfere with the process, and how quickly is the sensation changed. Few there are who have not felt the agony of colic pain, due to stoppage of digestion. What suffering is greater than the sense of awful suffocation from a heart that is not acting well?
These are only familiar illustrations of a thousand and one distressing derangements and symptoms that come from exhaustion and prostration of the nervous system.