[Music] and this animation we want to show the human immune system with images never seen before we will learn how macrophages as well as other cells and mechanisms protect our organism from Death every day our skin like the bulk of a tree represents valuable protection however the skin is also home to countless microorganisms among other things they are nourished and protected by an oily fluid called sebum sebum is produced by sebaceous glands sebum also contains antimicrobial elements that can kill microbes if they are harmful or too many microbes on the skin the sebum is composed
in such a way that these microbes are killed this creates a harmonious coexistence between skin cells and microbes a kind of symbiosis microbes also keep one another in balance and kill pathogens that can be dangerous to our cells foreign the protective layer of hollow organs such as nose mouth and trachea is a mucous membrane mucous membranes possess cilia psyllium of back and forth in a wave-like manner this allows them to move mucus to which foreign substances adhere upward into the oral cavity [Music] if mucociliary clearance is not sufficient an attempt is made to achieve clearance
of unwanted particles through coffee this is done by inhalation followed by a sudden exhalation so that foreign substances are removed from the lungs and trachea the bone marrow has stem cells it is the birthplace for many different immune cells which we also call leukocytes stem cells divide to form daughter cells asymmetric or symmetric symmetric cell division results in either two stem cells or two progenitor cells as seen here [Music] the progenitor cells divide again and again thus a single stem cell becomes many immune cells or leukocytes common immune cell is the neutrophil some of the
neutrophils remain in the bone marrow While others make their way into the bloodstream [Music] [Music] our neutrophil belongs to the so-called innate immune system and moves through the blood vessels during inflammatory processes the endothelial cells of the blood vessels have special receptors thus initially there is weak adhesion than strong adhesion and finally the granulocyte goes through the endothelium this process is called diapedesis [Music] [Applause] the path through the connective tissue has already been made by other neutrophils our neutrophil only has to follow cytokines that is signal substances of other cells a process called chemotaxis [Music]
there they are bacteria everywhere they produce toxins and thus harm the cells of the organism a neutrophils job is to eat these bacteria this eating process is called phagocytosis in addition some of the neutrophils produce certain cytokines that attract other granulocytes other cells of the innate immune system or macrophages [Music] they arrive on the scene before neutrophils phagocytose bacteria and produce a signal substance tumor necrosis Factor it suppresses the feeling of hunger causes fever stimulates leukocyte production [Music] another leukocyte type is the T cell T cells possess receptors what do they need them for macrophages
or professional antigen presenting cells they have the ability to present antigens via certain proteins on their surface and this initiates certain processes some T cells can use their receptors to recognize exactly those antigens of the macrophages for which they have been trained in the thymus let us take a closer look at this cells are also formed in the bone marrow they then migrate via the bloodstream to the thymus because they mature on the thymus they are called tea for thymus cells in the thymus which is one of the primary lymphoid organs T cells form antigen
receptors afterwards they usually migrate to secondary lymphoid organs such as the lymph nodes and the spleen foreign [Music] organs naive T cells and dendritic cells meet the dendritic cells have already had cardiac with a pathogen and present the antigen on the surface they are also professional antigen presenting cells the Tesa scans the dendritic cell for the antigen for which the T Cell was trained in the thymus if it finds the antigen diesel activation begins and among other things Colonial expansion occurs the cell reproduces itself thousands of times these cells respond to a specific pathogen or
antigen [Music] then some diesels start their journey and migrate to other tissues once there the cytotoxic T cells scan other cells with their receptors to look for cells that have the specific antigen on the surface foreign their antigen on a cell they know that a pathogen for example is in the cell the cytotoxic T cells begin to induce apoptosis [Music] the cell's debris are eventually eaten by macrophages and New South Shore like [Music] there are not only cytotoxic T cells but others as well to your helper cells memory T cells regulatory T cells and others
T helper cells work hand in hand with B cells B cells possess receptors like T cells like T cells B cells also originate in the bone marrow they then search for their specific antigen in the lymphatic system or in the bloodstream if the B cell Finds Its antigen with its receptors either activation occurs immediately or the B cell moves into the lymphoid tissue where T helper cells weight t-huber cells as we've seen before were also trained for one specific antigen for this reason the B cell presents its antigen on the surface this allows the T
cell with its receptors to scan the B cell if it is the antigen for which the T cell has been trained it gives the starting signal for the division and maturation of the B cell foreign [Music] cells clonal expansion occurs thus thousands of new B cells or plasma blasts and plasma cells are generated from a single B cell [Music] memory B cells are also produced which will spring into action in the event of another subsequent infection during acute infection plasma blasts and plasma cells immediately begin to produce antibodies and they release these antibodies into the
bloodstream antibodies are also often called immunoglobulins [Music] the toxin the bacterium the antigen is in the blood the antibody just produced by the plasma cell can bind to it and this way for example a toxin can be rendered harmless and an antigen can be marked so that macrophages can recognize it more easily and phagocize it more quickly this process is called opsonization all immune cells have a stem cell as their origin it develops into progenitor cells and eventually into the immune cells just shown other important immune cells or natural killer cells and platelets platelets also
known as thrombocytes originate in the bone marrow from Mega carryocytes megakaryocytes have pseudopodia that extend into blood vessels of the bone marrow it is through the pseudopodia that platelets are emitted into circulation [Music] one Mega carrier site can produce one thousand to three thousand platelets this process is called thrombopoiesis [Music] the platelets move through the blood vessels of the body if injury to your blood vessel occurs hemostasis begins the platelets adhere first to the collagen fibers of the connective tissue and eventually adhere to one another [Music] this results in a quiet fragile platelet plug which
prevents the blood from escaping [Music] eventually fibrin strands form on the platelets which ensures a stronger plaque and it will bind more platelets and red blood cells thus a strong clot is formed [Music]
