Biology - Immunology

[Music] [Music] throughout life the body's immune system plays a key role in its def def against harmful [Music] Invaders bacteria cause tetanus venial disease and tooth decay fungi cause athletes [Music] foot parasites like protozoa cause malaria parasitic worms cause hookworm and [Music] schistosomiasis viruses cause polio syphilis herpes and perhaps some [Music] cancers in addition immune system imperfections lead to such problems as allergies and acquired immunity deficiency syndromes AIDS this is a report on on our current understanding of the body's immune [Music] system the body's immune system includes a self-contained Army of cells and chemicals that defend those cells attack by invading antigens from [Music] outside microcinematography clarifies this process all the defender cells called lucites and Defender molecules are carried by the arteries veins and capillaries to sites of infection [Music] timelapse filming reveals normal body cells undergoing movement and growth such normal cells shown here dividing consist of a nucleus surrounded by jellylike cytoplasm with a complex outer membrane one form of antigen Invader the virus attacks and destroy cells directly attaching to cell membranes viruses inject nucleic acid which take over the cell's genetic mechanism so viruses multiply within the cell the boiling effect is due to the tiny viruses which cause lesions released they infect nearby tissue so the infection spreads how is the virus infection eliminated time-lapse filming shows lymphocytes hunting virus infected cells contacting cell surfaces they inject lymphotoxins which poison and kill infected cells or they puncture cell membranes causing leaks which lead to cell death the lymphocytes select and kill only cells containing the virus normal healthy cells are left intact the antibodies in this animation are molecules with specific immune system roles produced by lymphocytes one class of antibodies combines with antigens to inactivate them [Music] directly other cells called phagocytes are directed by immune system chemicals into the infected areas whereupon they close in on antigens and attach to them fyes then engulf the Invaders and the foreign substan is digested and [Music] neutralized besides engulfing antigens fyes May aided by other immune system components kill them directly the immune process is complex and difficult to visualize here using animation we can view a [Music] simplification invading antigens in this case viruses enter the body and seek out vulnerable tissue attaching to cell membranes viruses cause cell surface alterations [Music] gaining control the viruses copy themselves in large numbers mature and blow up the cells releasing the new viruses these scatter and attack more cells as the viruses multiply so the infection spreads to ward off the infection an immune response must occur the first step Defender cells must be able to recognize viruses and virus infected cells the virus antigen may actually contact a fagite which then processes and makes available antigen material to the te- cell another component of the immune system in any case the fosy gives an antigen description to the t- cell or t lucsy this t- cell processes it and becomes activated it can now recognize viruses and virus infected cells the t- cell response is to increase the number of Defender cells the immune system now makes many types of te- cells helpers killers and others all of whom can recognize the Invader antigen orders also go out to other Defender cells one set of orders command special killer cells to attack infected cells only those already invaded by virus antigens are destroyed [Music] t- cell messages are sent as chemicals the first chemical message MF microage activating Factor alerts and arms all phagocytes against the virus antigen a second chemical message chemotoxic Factor CF directs fago sites to the Battle Zone as they arrive a third chemical message m M migration inhibition Factor keeps them in the infected [Music] Zone the fago sites recognize the Enemy by special cell surface qualities then kill those infected cells engulf virus particles and debris and digest them however fos sites may also be overwhelmed giving the antigens the upper hand the t- cell then signals for more Defenders with the chemical messenger MF mitogenic [Music] factor of these the B cells make antibodies molecules which destroy this particular Invader virus antibodies May kill the virus directly or bind several viruses together so phagocytes and killer cells can destroy them [Music] antibodies can also adhere to antigen coated cells helping fagos sites and killer cells to destroy them other specialized te- cells joining the body's defense include the helper cells which communicate with te- cells and B cells in making antibodies the B cells stockpile antibodies for future use strengthening the body's immune response other te- cells the suppressor cells regulate and inhibit antibody production a lymphotoxin a biochemical substance is released which destroys virus filled cells another biochemical substance interferon or if inactivates viruses new Defenders including mediator cells are directed to the infection by msf migration stimulation Factor the cells carry biologically active molecules which prepare access routs to the infection by slowing blood flow and widening blood vessel pores giving Defender cells quicker access to the viruses [Music] meanwhile natural killer cells patrol the body destroying virus infected body [Music] cells they also play a key role in dealing with various cancers the new bees T's mediators and fago sites Vanquish the antigen but many are dead and some tissue destroyed more phagocytes move in to clear away the debris and dead tissue gradually destroyed cells are replaced by new ones healing occurs and the body's immune response remains [Music] Victorious although the immune system wins most battles against diseases in some cases Invaders may be difficult to destroy and can bypass the cellular and chemical defenses in such cases the battle May rage on seriously damaging body tissue and new clinical problems May ensue thereby requiring medical [Music] intervention nevertheless in recent years fundamental discoveries in Immunology have profoundly Advanced the development of every branch of medicine and surgery Sciences expanding knowledge of the immune response appears to be a major key to the preservation of good health from infancy to old age [Music]