The Heart-Pump and Its Pipe-Line System : Part 2

A Handbook of Health
by Woods Hutchinson

(Page 13 of 30)

This oxygen is picked up by, and combines with, the red coloring matter of the millions of little oxygen sponges, or baskets - the red corpuscles - and turns them a light red color, causing the blood to become bright red, such as runs in the arteries and is known as arterial blood.

The loops of tiny capillaries around the air cells of the lungs run together again to form larger pipes; and these unite, at the point of each lung nearest the heart, to form two large blood pipes - one from each lung - which pour the rich, pure blood, loaded with both food and oxygen into the left side of the heart. The left side of the heart pumps this blood out into the great main delivery-pipe for pure blood, known as the aorta, and this begins to give off branches to the different parts of the body, within a few inches of where it leaves the heart.

One of the first of these branches to be given off by the aorta is a large blood pipe, or artery, to supply the shoulder and arm; this artery runs across the chest, thence across the armpit, and down the arm to the elbow. Here it divides into two branches, one to supply the right, and the other the left, side of the forearm and hand. These branches have by this time got down to about the size of a wheat straw; the one supplying the right side is the artery which we feel throbbing in the wrist, and which we use in counting the pulse. From it run off smaller branches to supply the thumb and fingers. These branches break up again into still smaller branches, and they into a multitude of tiny capillaries, which run in every direction among all the muscle cells, delivering the food and oxygen at their very doors, as it were. The muscle cells eagerly suck out the food-stuffs, and breathe in the oxygen of the blood; at the same time, they pour into it their waste stuffs of all sorts, including carbon dioxid. These rob the blood of its bright red oxygen color and turn it a dirty purplish, or bluish, tint.

The loops of capillaries again run together, as they did in the liver and in the lung, to form tiny veins; and these run together at the base of the thumb and in the wrist, to form larger ones through which the now poor and dirty blood is carried back up the arm over much the same course as it took in coming down it. Indeed, the veins usually run parallel with, and often directly alongside of, the arteries. The blood passes through the armpit, across the chest, into the great main pipe for impure blood, the vena cava, and through this into the right side of the heart, where it again meets the rich, but waste-laden blood from the food tube and liver, and starts on its circuit through the lungs and around the body again.

The blood reaches every portion of our body in precisely this same manner, only taking a different branch of the great pure-blood delivery pipe, the aorta, according to the part of the body which it is to reach, and coming back by a different vein-pipe.

Why the Arteries are more deeply Placed than the Veins. In the limbs and over the surface of the body generally, the arteries are more deeply placed than the veins, so as to protect them from injury, because the blood in the arteries is driven at much higher pressure than in the veins and spurts out with dangerous rapidity, if they are cut. Some of the veins, indeed, run quite a little distance away from any artery and quite close to the surface of the body, so that you can see them as bluish streaks showing through the skin, particularly upon the front and inner side of the arms.

The Capillaries. Of course, the blood pipes into which the food is sucked through the walls of the food tube, and those in the lung, through which the oxygen is breathed, as well as those in the thumb through which food is taken to the muscle-cells, have the tiniest and thinnest walls imaginable. For once, the name given them by the wise men - capillaries (from the Latin capilla, a little hair) - fits them beautifully, except that the hairs in this case are hollow, and about one-twentieth of the size of the finest hair you can see with the naked eye. So tiny are they that they compare with the big veins near the heart into which they finally empty much as the smallest and slenderest twigs of an elm do with its trunk. What they lack in size, however, they more than make up in numbers; and a network of them as fine and close as the most delicate gauze goes completely around the food tube between its mucous lining and muscular coat.

Though thickest and most abundant on the inner and outer surfaces of the body, every particle of the body substance is shot through and through with a network of these tiny tubes. So close and fine is this network in the skin, for instance, that, as you can readily prove, it is impossible to thrust the point of the finest needle through the skin without piercing one of them and "drawing blood," as we say, or making it bleed. From this network of tiny, thin-walled tubes, the body-cells draw their food from the blood.

The Meaning of Good Color. It is the red blood in this spongy network of tiny vessels that gives a pink coloring to our lips and the flush of health to our cheeks. Whenever for any reason the blood is less richly supplied with food or oxygen, or more loaded with "smoke" and other body dirt than it should be, we lose this good color and become pale or sallow. If we will remember that our hearts, our livers, our brains, and our stomachs, are at the same time often equally "pale" and sallow - that is, badly supplied with blood - as our complexions, we can readily understand why it is that we are likely to have poor appetites, poor memories, bad tastes in our mouths, and are easily tired whenever, as we say, our "blood is out of order." The blood is the life. Starve or poison that, and you starve or poison every bit of living stuff in the body.

Houghton Mifflin Company
Copyright, 1911, By Woods Hutchinson
All Rights Reserved
Tenth Impression

About the Author

Woods Hutchinson (1862-1930) was an American physician, born at Selby, Yorkshire, England. He graduated from Penn College, Oskaloosa, Iowa, in 1880 and received his medical degree from the University of Michigan four years later. He worked as a professor of anatomy at the State University of Iowa and then became a professor of comparative pathology at the University of Buffalo.