The Blood (1961)

this is blood we shall use this sample to learn something about its composition as we begin our investigation of how the blood assists in the maintenance of life in our first test we are filling a tube so that we can spin it in a centrifuge when blood and spun at high speed we find that centrifugal force has caused the blood cells which are heavier than the liquid part of the blood to move outward towards the bottom of the tube leaving a slightly cloudy liquid at the top this liquid called plasma is about ninety two percent water the other eight percent are chemicals in solution they include salt that supply the cells with mineral matter and provide a proper medium in the body without which there can be no life antibodies that aid in fighting disease organisms fibrinogen that helps the blood to clot hormones that stimulate and regulate certain activities of the body albumins and globulin which help maintain the fluid volume of the blood foods which supply energy and building materials for growth and repair anabolism in the cells the red blood cells make up about forty-five percent of the Bloods total volume the narrow cloudy layer just between the plasma and the red cells contained quite blood cells and blood platelets and represents about one percent of the total volume we can study the struck by preparing on a microscope slide treating this smear with a stain makes the blood cell easier to see through a powerful microscope we can clearly see the red cells compare these red blood cells with living red blood cells each red blood cell is a minus disk concave on each side and about eight microns in diameter normally there are about 300 million of these in a single drop of blood by mixing blood with an exact proportion of a special fluid in order to dilute it we can estimate the number of red corpuscles this is a common test which gives important information about a person's state of health a small amount of diluted blood is placed on a ruled microscope slide the technician determines the number of red cells per cubic millimeter by finding the average number in the measured spaces of the slide in healthy blood there are usually about five million red cells per cubic millimeter any great increase or decrease in this number of red cells is a warning signal to the doctor the blood also contains white cells or corpuscles these are monocytes these the neutrophils unlike the red cells white cells have nuclei you can see the structure of a white cell or leukocyte in this drawing of a stained sell the entire dark area of this cell is the nucleus it is surrounded by cytoplasm blood cells are produced in the bone marrow here we see the taking of a sample of live bone marrow this is commonly done to study the performance of the blood making mechanism of the body this is a diagram of the breast bone from which the sample was taken here you can see many new cells in different stages of development the dark cell in the center is an early stage of a red cell at this stage it contains a nucleus eventually the red cell loses its nucleus before entering the bloodstream here we see typical red cells without nuclei red cells live about four months in the bloodstream this cell is developing into a mature white cells white cells are thought to live no more than a few days in the bloodstream worn-out blood cells are removed from the circulating blood by the liver spleen and bone marrow the chemical composition of the blood changes as it travels through the circulatory system which is divided into two main parts the flow between the heart and the lungs is called a pulmonary circulation blood from the body enters the heart and is pumped to the lungs here the blood gives off carbon dioxide collected in the body tissues a substance in the red cells called hemoglobin combines with oxygen changing the color of the blood from blue red to bright red the blood then returns to the heart to be pumped out to the body through the systemic circulation blood in the systemic part of the circulatory system carries oxygen and other elements to all the cells of the body and removes waste food elements are introduced in a part of the systemic circulation called the portal circulation these food elements are chemical products resulting from digestion they are carried by the blood to the liver for storage and for further chemical change blood travels out from the heart through arteries which keep branching into smaller vessels called arterioles finally they branch into a network of microscopic capillaries spreading among the body cells the red cells changed from bright red to blue red as they give off oxygen and take on carbon dioxide the blood then goes to tiny veins called venules which join into larger veins eventually the blood returns to the heart where it is pumped to the lungs and the process begins all over again here is a capillary network actually photographed in a living animal let us see in greater detail what happens here some capillaries are so tiny that red cells must pass through them in single file as they do oxygen shown here by white dots passes from the hemoglobin of the red cells through the capillary walls to the surrounding tissue carbon dioxide shown by black dots is taken on by the red cells and the plasma food materials as well as carbon dioxide are carried by the liquid part of the blood the plasma they pass out to the body tissue while waste products from the body enter the plasma in this tremendously enlarged view of living tissue you can actually see the red cells passing through a capillary in single file here you can see the larger white cell white cells are not carried along by the plasma as rapidly as the red cells are in addition white cells have the power of independent movement white cells can pass outside the bloodstream through the capillary walls by virtue of this independent movement they can destroy harmful bacteria shown here as small black dots when bacteria invade the body protective substances called antibodies shown here by white specks are produced and carried by the bloodstream when certain of these antibodies combined with the bacteria the white cells can surround and dispose of them more easily blood platelets are important in blood clotting here you can see a platelet caught on the wall of a blood vessel for comparison notice the flight sale just above the platelet there are several million platelets in every drop of blood they are smaller than either red or white cells when there is a flesh wound a series of reactions takes place that leads to blood clotting blood clots faster when it's warm than when it's cold this can be easily demonstrated here are two tubes of blood at different temperatures one at the freezing point of water the other at body temperature what causes blood to clot to begin with a cloth consists of the formation of threads of the blood Prothean fibrin here are the fibrin threads freed of the other substances in the blood these threads in a wound stop the flow of blood by closing off the open blood vessel the clotting mechanism of blood is in the plasma we can show this by removing the plasma from a tube of centrifuged blood now we add to the second tube only some of the juice that comes from injured tissues tissue juice contains a substance which activates the blood clotting mechanism since this tube contains only plasma we have demonstrated that plasma can clot when exposed to tissue juice and that red cells are not necessary for clotting without the Bloods ability to clot even small wounds might result in bleeding to death this blood defect called haemophilia is hereditary and requires special treatment clotting occurs within blood vessels when internal damage to the vessels takes place this may result either from a blow on the skin or from infection sometimes a cloth gets into the bloodstream eventually it blocks a blood vessel this damages the organ in which it is lodged causing damage or death depending upon the size of the vessel affected in the brain this causes one form of stroke sometimes there is a great loss of blood doctors have learned how to replenish the natural supply through blood transfusions an untold number of lives has been saved to the discovery of this technique it has been learned that blood from different persons may have different characteristics we have developed a process of blood typing using two types of serum usually colored yellow and green for identification the blood being typed is mixed with these two singh agents the red cells may mix evenly with the typing serum or they make clump and break up the reaction that occurs identifies a blood type these cells show clumping while the cells in this serum do not clump there are four main blood types or groups most of the people you know will be either in group O or group a a few will be in Group B and fewer still in group a be another characteristic of blood is the Rh factor this factor is identified in much the same way as basic blood grouping is done most people have the factor and are called rh positive the few who r rh negative should not receive rh-positive blood should the mixing of dissimilar types of blood in the body cause the kind of clumping you see here the result might be fatal every person should know his own blood type so that he can receive or give blood in an emergency in this film we have examined some aspects of blood the highly complex fluid which is a lifeline of the body we have noted the major elements of the liquid portion of the blood the plasma which makes up more than half its volume we have observed in detail the structure of the red corpuscles and have seen that they carry oxygen and carbon dioxide as they flow through the body we have seen to how the constancy of the blood is continually maintained as it performs the numerous actions required to sustain life these include the collection of food from the intestines and liver the exchange of gases in the lungs and the ridding of liquid wastes through the kidneys in these and other ways the blood