THE CARETAKER
THE CARETAKER
MY: Just see, mother! I have cut my finger. See how fast the blood runs out! Oh-h!
Mother: Suppose we let a drop fall on this glass and then try to find out what it is made of, what it does in the body, and about the different rooms it visits. You may ask questions and I will try to answer them; but first we will bind up the cut finger in this bit of soft cloth. We have already learned how blood is made, but we want to learn what it does for us.
Blood is made from the food you eat and the water you drink. If you eat good food it makes good blood. Bad food and drink make bad blood. It might be called the caretaker, or the housekeeper of the body. Without it your body-house would go to ruin; for the Bible says, “The life of all flesh is the blood.” After passing through the kitchen, serving room, and dining room, the blood enters a dark tunnel and comes to your heart.
Helen: But what makes it such a bright red color?
Mother: Because it has millions of little red bodies called cor´pus-cles. Really it is a pale yellow, but there are so many of these tiny folk floating around that they make it look red, just as a river would if it were packed full of tiny red fishes, or as water would if you should fill a bottle with very small red beads and then cover them with water.
Percy: But are all the cor´pus-cles red?
Mother: No; some are white, but there are many more red than white.
Corpuscles.
Amy: What do they look like?
Mother: You can not see them at all unless you should look through a mi´cro-scope. The red cor´pus-cles are shaped like a little biscuit with a dimple in the middle. The white ones keep changing their shape in a very wonderful way. First they are round, then square, then three-cornered, and they take on ever so many other shapes. There are several millions of these little red and white fellows in a single drop of blood.
Elmer: But you said it went through a dark tunnel to get to the heart. Please tell us about that.
Mother: The tunnel is round, like a tube, and I must tell you that these tubes are in every part of your body. Some are quite large, some are small, and some are so tiny that you could not see them if you should try. They are like a tree with its trunk dividing into large branches, and these into smaller ones, till at last they become little twigs. The largest tubes for carrying blood through the body are called arteries. The smaller ones are called veins. The arteries carry fresh, bright, clean blood to every part of your body-house. It bounds along with a hop, skip, and jump, as though it were in a hurry to get to work. The arteries have very strong walls, and, as I told you, the blood soon finds itself in the heart.
Helen: Which room did it go into first?
Mother: When the blood is fresh and clean it goes into the top room on the left side. It keeps coming in until the room is filled full. Then the little folding doors open, and the blood is crowded into the lower left room, the doors fly back, and—
Amy: But please tell us about the doors.
Mother: They are made so that the blood could not get back into the top room if it wished; for they never swing but one way, and some small cords hold them in place. These doors are called valves. When the lower room is filled, the walls press together, and the blood is forced into the largest blood tube in the body, the walls of which are so very smooth, that the blood passes along with a merry bound. The tube keeps growing smaller the farther we go from the heart, and branches into many smaller tubes.
Percy: And how far does the blood go?
Mother: Perhaps it first takes a trip through the trunk of your body, down through your right leg, and on to the end of your big toe. The tubes at last become very small, and there are so many of them that they are like a network of the finest lace. A hair would seem like a big rope beside them. They are so very tiny that you can not see them. Their walls are thinner than tissue paper, and they are so close together that you can not touch your skin with the point of a needle without touching some of them. When the blood comes to these tiny tubes, it does not travel so fast as at first, and as it passes along, the muscles pick it to pieces, take the part they want as food, and load the blood down with waste which they can not use. When they are so hungry, the blood is glad to feed them and give them the oxygen, which makes them warm.
Amy: Did it stay long in those little tubes?
Mother: No; it went through as quickly as it could, and on its way back found itself in bigger tubes, which keep growing larger; for it is now on its way back to the heart. This picture will help you to see the road it travels. It is now a dark red color, and unfit to work longer till it is washed. Back it goes to the heart, the tubes through which it travels growing larger all the way until it tumbles into the right top room of the heart, which, as you have learned, always has dirty, worn-out blood in it. But it is not allowed to stay there; for between this room and the lower right room there are three folding doors kept in place like the two on the left side, and through them it passes. The walls of the rooms on the right side of the heart are not as thick as those on the left side. I think that must be because the left side sends the blood farther than the right.
Helen: Does the blood stop to rest in the lower right room?
Mother: Oh, no; it never rests as long as there is any life in it! The heart squeezes it out into another big tube, and it soon finds itself in the bath room, where it is washed through and through, and its color becomes as bright red as when new.
Amy: And where does the blood then go?
Mother: Straight back to the left side of the heart, where it is pumped out the same as before; and this time we will say it goes to the kitchen of the house you live in, and helps the cook get the dinner you have eaten ready to be made into more blood. The old blood eats some of the good things, and again it is sent to the right side of the heart and back through the bath room.
Percy: And what then?
Mother: Its next trip may be taken to the brain, to help a little girl learn her lessons in school. The brain takes what it can use, and back the blood goes to the right heart, around through the bath room again, and the next time it may be sent to the liver, where it finds sugar and bile-making going on, as usual.
Elmer: But how can the blood be of any use there?
Mother: I think you would not ask such a question if you could go there to see. It “takes all the starch out of it,” as you sometimes say, and some other things besides, to make into sugar. It also uses part of it to make into bitter bile, so you may well believe that when it goes back to the heart there is not much left that is of value. But after a good wash in the bath room the blood goes back to the heart, and this time may be sent to the bones in your fingers, and they take what lime it has. This drop was just making its way back to the heart again when Amy cut her finger and let it out.
Percy: But I should have thought the blood would have been worn out making so many trips.
Mother: So it would if it was not made new by the food you eat. It keeps taking as well as giving as it goes round and round through the body. You would not expect a housekeeper to keep everything tidy and clean in a house, and not give her what she needed to make her strong and able to work; and so the master of the house gives the blood plenty to eat; and it makes no complaint as long as it can do its work well. It is a very busy person, we might say, and, as there is no end of things to do in the house in which you live, the blood works night and day.
Elmer: But I don’t see how the blood can take with it all that is needed to mend the different parts of the house.
Mother: It is supposed to carry with it a supply of everything that is needed to keep the house in order as it goes, so that when a bone says, “I want some lime,” or a muscle says, “Please give me some al-bu´men,” each part gets what it calls for if it is in the blood. Whether it has what every part needs depends on what the master of the house sends into the kitchen to make blood. Have I told you about the filters in the body?
Amy: I’m sure you have not. Please tell us now.
Mother: There are two of them in the lower part of the trunk close to the back, one on each side. They are the shape of a bean, and are called the kidneys. The blood passes through them, and some of the poisons it has picked up are strained out and sent to a storeroom, called the bladder, where they are kept till the brain gives an order to send them away.
A kidney.
Helen: But there is one thing I would like to know. I can see how blood can run down-hill into our fingers and toes, but I can’t see how it can climb back up to the heart again. Will you please tell me?
Mother: The heart is the power that sends it through the arteries to every part of the body, whether it is up-hill or down. Now when the blood has come to the end of its journey, and has reached the tiny hair-like veins of which I told you, more blood keeps coming down and pushes it on till it starts back through the larger veins. The blood keeps crowding behind, and the veins are made in such a way as to help it climb up.
Percy: But how are they different from the arteries?
“Veins have tiny pockets in them.”
Mother: Did you ever see little watch-pockets hung in bedrooms in which to put watches? Well, the veins have tiny pockets in them, as you see in the picture.
Amy: But I don’t see how that helps the blood in climbing.
Mother: It is this way: If you had a tube with little pockets and should hold it so the top of the pockets was down, you could pour anything through it and they would not stop it from passing. But turn the tube the other way, with the pockets up, as you see in the picture, and they would catch and hold anything you tried to pour through the tube. It is the same way with the veins and the blood. If the blood should try to go back, the pockets would fill full and hold it, but when it is passing up toward the heart, they let it slip by without holding it back.
Elmer: Then the blood keeps going round and round in the body, and never stops.
Mother: Yes; and this “going round and round,” as you say, is called the cir-cu-la´tion. This drop of blood would have kept going until it was used up in mending your body and helping keep it alive, if it had not slipped out through the cut in Amy’s finger into the world in which you live and move.
I know you have all enjoyed hearing how the blood travels through the body. Let me tell you a little story I read of what a boy said in school. His teacher asked him to tell the class how the blood cir´cu-lates, or goes round and round.
“Please, sir,” said the lad, “the blood goes down one leg and up the other.”
“Very clever of it, I am sure,” said the teacher. “How does it get across?”
Perhaps that was something the boy had not thought of, and I am sure you would never give such an answer as that since you have heard the story of a drop of blood. Let us see the cut finger where it came out.
Amy: It doesn’t bleed at all now, mother.
Mother: No; and that makes me think to tell you something else about this wonderful caretaker. If we had a quart of blood and should let it stand awhile, it would become thick like jelly. But if you should take a bundle of twigs and keep stirring it round and round, it would not get thick at all. If you looked at your bundle of twigs after stirring the blood with it, you would find the twigs covered with a sticky substance. If you should wash them, you would wash away the red color, and would have left a soft, stringy mass all matted together.
Helen: But what is it good for?
Mother: It is called fibrin, and if it were not in the blood, you would bleed to death if you cut yourself. So long as the blood stays in the body, the fibrin goes quietly with it wherever it goes; but if it begins to run away, as it did from Amy’s finger, the fibrin goes to work at once to cork up the place so it can not get out.
Percy: How long does it take the blood to go from the heart through the body and back again, mother?
Mother: I am sure you will be surprised when I tell you that the heart sends it with such force that it will go to the farthest part and get back in from three to eight minutes, and some say it takes even less time than that.
Elmer: What! so quickly as that! It does not seem possible.
Mother: And though one-eighth of the body is blood, yet it will all pass through the heart in about the same time.
Helen: How wonderful! But I don’t see how all these little things in the blood, called cor´pus-cles, can get through the tiny, hair-like veins, which are so small.
Mother: We can learn a useful lesson from them, and you would be pleased, I know, to watch them, if they were only large enough so you could. They seem to know just what they want to do, and where they ought to go. When the little veins are too small for more than one to go in at a time, they do not push or crowd one another. One row waits as politely as can be till the others have passed in, and then they follow. How wonderful it is to think of this river of life flowing round and round, and we feel nothing of it but the gentle tap, tap of the heart as it sends it bounding through every part of the body! Should it stop, we would die; for “the blood is the life.”
Percy: But how did people find out that the blood goes around as it does?
Mother: A doctor in England, named Harvey, first discovered it. Before his time people thought air went around through the body in the arteries. Men have studied the subject since Dr. Harvey lived, and they keep learning more about it all the time.
Amy: Does water go into the blood, mother?
Mother: Yes; it very quickly finds its way there, and it is the same with strong drinks, such as beer and whisky. It only takes a very few minutes for anything we drink to get into the blood stream.
The walls of the veins and arteries are governed by the nerves of our telephone system. They let just the right amount of blood flow through them all the time. When alcohol gets into the blood, it puts the nerves to sleep, and so too much blood goes into the little veins. You know a man who drinks has a red face. If he drinks a long time, his nose gets so red that it is called a “rum blossom.” This is because so much blood goes to his nose that it becomes large and red. Alcohol also makes the walls of the arteries weak, so they sometimes burst open and the person dies.
Now that we have learned a few things about the blood, we must be careful what we give this care-taker of the body to eat. We have learned very little of what there is to know, and as you grow older I hope you will study and learn more.