Circulation And The Human Body (1959)

[Music] [Applause] [Music] the human cell Manute fragment of living matter the building blocks of which we are made a hundred million cells to make an eye an artery a tooth a billion cells to make a uterus a liver a rib over a trillion cells to make a human being you usually don't think of the food you eat or something to keep yourselves alive and healthy you probably think of all the various kinds of exercise as being fun rather than something that the cells of your body need and you hardly say to yourself that you're going to get some sleep to take care of your trillion odd cells but that's what you're doing here for instance is a long muscle cell that contracts and relaxes each time the muscle moves this cell needs many substances in order to function the chief among them are food and oxygen this is fuel that provides you with energy to chase a ball or swim or wrestle as fuel is consumed in the cell waste products are created that must be removed among them carbon dioxide the harder you exercise the more food and oxygen the cell needs and the more waste products it creates the cell needs exercise to be healthy and after exercise rest during rest the cell is replenished these processes must go on constantly not in one cell but in a trillion how are these needs serviced by the intricate system of vessels through which blood is circulated by the body's astonishing pump however the large arteries and veins are only the transportation system the means of delivering blood to the capillaries these are microscopic vessels with walls so thin that substances can pass back and forth through them from the blood to the cells actual capillaries look like this here food and oxygen are delivered from the blood to the cells of the body and here the cells waste products are picked up this bluish blood from the capillaries laden with waste products is collected first in Manute veins called venules each venule empties into a network of veins which join others in larger and larger channels they bring the blood back to the heart this remarkable muscle is really two pumps rather than one the Chamber's on this side provide the force to send the blood out through the lungs the pulmonary circulation we call it when the blood returns from the lungs it goes to the chambers on the other side of the heart the pump on this side forces the blood out through the body the systemic circulation it's called the upper chamber on each side is called the atrium or sometimes the article the lower chambers are called ventricles the blood flow can be followed better in this diagrammatic drawing of the heart the blood returns to the heart by two great veins one draining the lower and the other the upper part of the body it flows in and fills the right atrium actually the Chamber's on the other side of the heart work at the same time but we will follow the passage of blood one step at a time to avoid confusion as the atrium fills the valve between the two chambers opens and allows the blood to flow into the right ventricle the atrium contracts and forces in the final bit when the ventricle contracts next this valve snaps shut and this one opens each contraction forces blood into the lungs in the lungs the bluish blood gets rid of its load of carbon dioxide one of the waste products picked up from the cells and here also it takes on its fresh supply of oxygen when the blood flows back into the other side of the heart the oxygen has turned it bright red once again the atrium contracts pushing the last bit of blood into the ventricle when the ventricle contracts this valve will be forced closed while this one opens the blood is pumped out into the body through the great arched artery the aorta and this is the way the heart actually operates both sides in unison and now at normal speed this is about the speed that your heart beats when you're getting ready to go to bed or you're doing your homework but when you're exercising your cells need more fuel and oxygen your heart must pump your blood faster to supply the need this too is normal a young strong heart is perfectly able to beat at this speed for long periods of time take your pulse after your next wrestling match and you can feel how your circulation system takes care of the increased need when the blood leaves the heart branching arteries take some of it to the head arms and upper part of the body the aorta itself continues downward branching innumerable times to supply the lower parts of the body these arteries are not just simple tubes each one is composed of a layer of elastic muscle fiber lying between a smooth inner lining and an outer layer of tough fibrous tissue the larger arteries expand with the force of blood then spring back after each heartbeat thus helping to maintain pressure to keep the blood moving along at all times in the smaller arteries this ability to dilate and contract has a different function it controls the flow of blood needed by the cells in that part of the body watch these smallest arteries are called arterioles they branch at last into caps the circle is complete here the food and oxygen pass out through the capillary walls to yourselves to keep them healthy all your life long yourselves and your remarkable circulation system work for you but you have to work for them too to keep yourselves healthy you have to give them the right foods you have to give them exercise you have to give them rest the hundred million living cells that make an ear a mouth a thyroid gland the billion living cell a heart [Music] [Applause]