The Circulation : Part 3

Hygienic Physiology: with Special Reference to the Use of Alcoholic Drinks and Narcotics
by Joel Dorman Steele, Ph.D.

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The Velocity of the Blood varies so much in different parts of the body, and is influenced by so many circumstances, that it can not be calculated with any degree of accuracy. It has been estimated that a portion of the blood will make the tour of the body in about twenty-three seconds (FLINT), and that the entire mass passes through the heart in from one to two minutes.

Distribution And Regulation of the Heat of the Body.

1. Distribution. - The natural temperature is not far from 98°. This is maintained, as we have already seen, by the action of the oxygen within us. Each capillary tube is a tiny stove, where oxygen is combining with the tissues of the body. Every contraction of a muscle develops heat, the latent heat being set free by the breaking up of the tissue. The warmth so produced is distributed by the circulation of the blood. Therefore the arteries, veins, and capillaries form a series of hot- water pipes, through which the heated liquid is forced by a pump - the heart - while the heat is kept up, not by a central furnace and boiler, but by a multitude of little fires placed here and there along its course.

2. Regulation. - The temperature of the body is regulated by means of the pores of the skin and the mucous membrane in the air passages. When the system becomes too warm, the blood vessels on the surface expand, the blood fills them, the fluid exudes into the perspiratory glands, pours out upon the exterior, and by evaporation cools the body. When the temperature of the body is too low, the vessels contract, less blood goes to the surface, the perspiration decreases, and the loss of heat by evaporation diminishes.

Life By Death. - The body is being incessantly corroded, and portions borne away by the tireless oxygen. The scales of the epidermis are constantly falling off and being replaced by secretion from the cutis. The disks of the blood die, and new ones spring into being. On the continuance of this interchange depend our health and vigor. Every act is a destructive one. Not a bend of the finger, not a wink of the eye, not a thought of the brain but is at some expense of the machine itself. Every process of life i. Therefore a process of death. The more rapidly this change goes on, and fresh, vigorous tissue takes the place of the old, the more elasticity and strength we possess.

Change of Our Bodies. - There is a belief that our bodies change once in seven years. From the nature of the case, the rate must vary with the labor we perform; the organs most used altering oftenest. Probably the parts of the body in incessant employment are entirely reorganized many times within a single year.

The Three Vital Organs. - Death is produced by the stoppage of the action of any one of the three organs - the heart, the lungs, or the brain. They have, therefore, been termed the "Tripod of Life." Really, however, as Huxley has remarked, "Life has but two legs to stand upon." If respiration and circulation be kept up artificially, the removal of the brain will not produce death.

Wonders of the Heart. - The ancients thought the heart to be the seat of love. There were located the purity and goodness as well as the evil passions of the soul. Modern science has found the seat of the mental powers to be in the brain. But while it ha. Therefore robbed the heart of its romance, it has revealed wonders which eclipse all the mysteries of the past. This marvelous little engine throbs on continually at the rate of one hundred thousand beats per day, forty millions per year, often three billions without a single stop. It is the most powerful of machines. "Its daily work is equal to one third that of all the muscles. If it should expend its entire force in lifting its own weight vertically, it would rise twenty thousand feet in an hour." Its vitality is amazing. The most tireless of organs while life exists, it is one of the last to yield when life expires. So long as a flutter lingers at the heart, we know the spark of being is not quite extinguished, and there is hope of restoration. During a life such as we sometimes see, it has propelled half a million tons of blood, yet repaired itself as it has wasted, during its patient, unfaltering labor. The play of its valves and the rhythm of its throb have never failed until, at the command of the great Master Workman, the "wheels of life have stood still."

The Lymphatic Circulation is intimately connected with that of the blood. It is, however, more delicate in its organization, and less thoroughly understood. Nearly every part of the body is permeated by a second series of capillaries, closely interlaced with the blood capillaries already described, and termed the Lymphatic system. The larger number converge into the thoracic duct - a small tube, about the size of a goose quill, which empties into the great veins of the neck. Along their course the lymphatics frequently pass through glands, - hard, pinkish bodies of all sizes, from that of a hemp seed to an almond. These glands are often enlarged by disease, and then are easily felt.

The Lymph, which circulates through the lymphatic like blood through the veins, is a thin, colorless liquid, very like the serum. This fluid, probably in great measure an overflow from the blood vessels, is gathered up by the lymphatic, undergoes in the glands some process of preparation not well understood, and is then returned to the circulation.

Office of the Lymphatic. - It is thought that portions of the waste matter of the body capable of further use are therefore, by a wise economy, retained and elaborated in the system.

The lacteals, a class of lymphatic which will be described under Digestion, aid in taking up the food; after a meal they become milk white. In the lungs, the lymphatic are abundant; sometimes absorbing the poison of disease, and diffusing it through the system.

The lymphatics of the skin we have already spoken of as producing the phenomena of absorption, Nature in her effort to heal a cut deposits an excess of matter to fill up the breach. Soon, the lymphatic goes to work and remove the surplus material to other parts of the body.

Animals that hibernate are supported during the winter by the fat which their absorbents carry into the circulation from the extra supply they have laid up during the summer. In famine or in sickness, a man unconsciously consumes his own flesh.