Our Wonderful Body: The Heart And Its Work (1968)

[Music] all the time this boy is playing his heart is beating he doesn't hear it beating he doesn't even think about it unless he's in his doctor's office then if he listens through a stethoscope he might hear this and though most of the time we never notice it our hearts beat all day long and all night long and between each beat the heart rests beat rest beat rest but what really is a heart and what does it do well suppose you had a full-size model of yourself like this and suppose that model had a door in the chest then we could see what the heart looks like it's located in just about the center of your chest and it's about the size of your own fist what's your heart like well it's something like this hollow rubber ball if we attach a tube to this ball and stop up the other hole we can get some idea of the sort of work a heart does squeezing the hollow ball then letting it go draws water up into the tube squeezing the ball again forces the water out by repeatedly squeezing this hollow rubber ball we can use it to carry water from one place to another suppose we add a second piece of tubing to the rubber ball perhaps we can move the water faster from one dish to the other no now it isn't working at all but it worked before with one tube let's try closing up this second tube then squeeze the ball again now it's moving the water let's open this tube and close up the first one and squeeze again the water empties into the second dish instead of using our finger each time to open and close the tubes let's use valves these are like tiny doors that can quickly open and close the holes in the Rubber Ball we'll attach our tubes to these valves Now by squeezing the ball it lifts water from one dish and carries it to the other what we've made here is a simple pump it pumps water from one place to another but it could pump other things too it could just as easily pump pump water with gelatin in it or anything else whatever is in the water will be drawn up into the tubes and pushed along them by our pump and that's about what your real heart does except that each time your real heart squeezes it pumps blood it squeezes then relaxes squeezes relaxes our rubber ball heart only works when we use the muscles of our hands to squeeze it but your real heart is a muscle it squeezes itself then relaxes squeezes relaxes empties fills empties fills beat after beat day after day year after year pushing blood through a whole series of tubes called blood vessels to show how all this works we'll use our model again and and we'll use plastic tubes to represent the blood vessels in your body a very large blood vessel leads away from the heart then branches into smaller vessels almost like the branches of a tree in your real body many vessels go up to the head we'll use just one two on our model many go out to each arm again we'll just use one some reach the center part of the body still others stretch down into each leg these blood vessels reach into every part of your body all these vessels in turn Branch into much smaller ones called capillaries the real capillaries are so small they can't be seen without a microscope imagine that capillaries are everywhere on our model each time your real heart beats it pumps blood through the large blood vessels the blood moves along all the smaller branches and out into all the tiny capillaries but our model isn't complete yet another set of vessels brings all the blood right back to the heart again some of these vessels bring the blood back up from the legs some of them return the blood from the center of your body other vessels return the blood from your head sending it back to the heart what we really have is a series of Loops that carry blood back and forth between the heart and all the other parts of your body each time the heart squeezes blood is pumped through all these tubes around and around it goes to every every part of your body then back to the heart and as it moves through the body it carries things just like the liquid in our model is doing but what things well things like food your body needs food everyone knows how food gets into the body through the mouth but where does it go from there well there are other parts of your body for taking care of food when you swallow the food goes down this pipe to your stomach and then to your intestines there the food is changed into a kind of liquid and enters the blood in addition to food your body needs oxygen from the air and it takes other parts to bring that into the body when you breathe air enters your nose or mouth and goes in your lungs but how oxygen gets from the lungs into the blood is difficult and complicated in fact it's so difficult a second pump is used to help do the job actually your real heart is two pumps that work side by side all the blood returning from the different parts of your body empties first into this pump this pump then forces it into the lungs each time your heart beats blood moves through the lungs and picks up oxygen from the air you breathed in carrying oxygen the blood moves back to this pump which will send it all through the body both halves of the heart actually pump together each time the heart beats both sides Force blood forward through the system of blood vessels and as the blood moves through these vessels it carries with it food and oxygen each bead of your heart then delivers to every part of your body the things it needs things that make it possible for you to run and play shout and laugh talk and think your heart does this day after day and night after night do you suppose there are things you can do to help your heart continue to work [Music] well