Microorganisms That Cause Disease. (special version, 1960)

this is a hospital where patients come to recover from disease for x-ray for lab tests and sometimes for surgery but if you were suffering from an infectious disease the hospital laboratory would help identify your illness in the lab microscopes and other special tools are used to identify the tiny germs that cause infectious diseases some microorganisms or germs can cause diseases these germs for example cause pneumonia all microorganisms are either simple living plants such as these fungi or simple living animals such as these protozoa disease producing germs are found among each of the five kinds of microorganisms fungi bacteria viruses rets and protozoa some invade the circulatory system and produce toxins that poison the body some cause disease by invading the lymph system almost all disease producing germs are parasites they live in healthy tissue and organs thus destroying them so destroying of cells is the final result of all disease germs here we see some single celled fungi all fungi are plants that do not make their own food they depend upon other organisms living or dead for their food and life have you heard of athletes foot this is one example of what happens when disease producing fungi invade the body in this case the skin athletes foot is a common fungus disease this is the way the fungus looks under the microscope many of our serious infectious diseases are caused by bacteria bacteria are found really everywhere they are in our mouths and sometimes in other body tissue these bacteria normally in our mouths can often cause disease by destroying cells no scientists do not yet fully understand exactly how some bacteria destroy cells but they do know a great deal about bacteria for example a single bacterial cell is simply a mass of protoplasm surrounded by a firm cell wall bacteria secrete enzymes with which they digest food it is believed that it is such enzymes that destroy cells let's see some examp examples of how bacteria destroy healthy cells this tube contains human blood the red color of the blood comes from the red blood cells this bottle contains a toxin toxins are poisons made by disease producing germs this toxin is made by the streptococus germs this is what a streptococus looks like under the microscope when the streptococus toxin is added to the blood we will see that the red blood cells are destroyed in a short time the red liquid slowly becomes clear why because the toxin destroys the red cells and they disappear this is one example of how cells are destroyed by disease germs on this rabbit we shall see another way in which cells are destroyed we have shaved some of the hair from the rabbit's back we shall inject some disease bacteria under the rabbit's skin over a period of 3 or 4 days we can see that a sar is developing on the skin here too cells are destroyed by disease bacteria a virus is another kind of disease germ that destroys cells the virus you see here causes flu or influenza almost all viruses can only be seen through an electron microscope which can magnify germs more than 100,000 times viruses differ from other germs in that they can live and grow only inside tissue cells these polio viruses are about the size of a very large molecule viruses are sometimes infectious particles as we see here some may form crystals like this Crystal of polio virus let's see how a virus destroys cells this is a cross-section of a normal spinal cord notice the large nerve cells after infection by polio virus most of the large nerve cells have been destroyed in the laboratory we can see the effect of another kind of virus pneumonia virus this virus affects lung tissue we can infect this mouse by placing drops of virus solution in the mouse's nose the mouse's lung tissue before the infection is a healthy pink color after the virus enters the lung and causes pneumonia the lung becomes swollen and discolored let's see one more example of how disease viruses destroy cells these test tubes contain living human cells we infect the cells with a virus that causes upper respiratory disease in humans these microphotos show how the tissue cells are destroyed by the multiplying virus have you heard of other virus diseases there are many have you heard of the retzi ey rets ey look very much like the bacteria and like viruses they grow only in living cells ret ey are passed from animal to Animal by biting insects like like this tick to cause Rocky Mountain spotted fever we have seen the disease causing fungi and bacteria which are single celled plants and the smaller viruses and rets which seem to be related now let's look at the protozoa this is an amoeba one of the many different kinds of protozoa protozoa are the simplest members of the Animal Kingdom protozoa have many different forms some can move some cause disease this protozoan causes a Digestive Disease here is another protozoan seen in human blood this protozoan causes African sleeping sickness this diagram indicates how the protozoa which cause malaria destroy red blood cells when one of these protozoa enters a red blood cell as we see here it grows and starts to multiply within the cell within hours the cell is destroyed letting out more protozoa into the bloodstream these May invade other red blood cells like all other disease organisms protozoa do their greatest damage in those parts of the world where people live in crowded unsanitary conditions poverty and ignorance cause poor health practice and may lead to epidemics yes scientists already have many answers about disease germs but there are still many questions to be answered for example how do be bacteria destroy cells do viruses form cancers more study more research more answers are needed perhaps one of you may someday have an occupation that will help scientists in the battle against all germ diseases for