D9 - The Lymphatic System and Immunity PDF

D9 - The Lymphatic System and Immunity The Lymphatic System Lymphatic system: Network of vessels, glands, and nodes spread throughout body Collects fluid, called lymph, which is made up of interstitial fluid Connects to ou...

D9 - The Lymphatic System and Immunity The Lymphatic System Lymphatic system: Network of vessels, glands, and nodes spread throughout body Collects fluid, called lymph, which is made up of interstitial fluid Connects to our circulatory system at subclavian veins (below the collarbone) Lymph works with white blood cells to protect the body from infection ○ Lymphocytes mature in lymph node Lymph nodes also contain macrophages, which trap and destroy bacteria Human Defense System First line of defense for body is to prevent organisms from entering Skin and mucus that line respiratory passages serve to keep out most microbes Stomach acids, oils in skin, and enzymes in tears also break down bacteria Non-Specific Defenses Second line of defense: Cell-mediated immunity, which includes three types of white blood cells: ○ Neutrophils, monocytes, and macrophages kill bacteria using phagocytosis (ingesting bacteria) Natural killer cells target body cells that have become cancerous/infected by viruses Specific Defenses (Antibody Mediated Immunity) Third line of defense is immunity Developed by actions of specific defenses using antibodies, called antibody mediated immunity Antibodies: Proteins that recognize foreign substances and either neutralize or destroy them Lymphocytes are primarily responsible for this immune response Body can recognize proteins and other molecules as being part of the “self,” and therefore, knows what to protect against T & B Cells - Lymphocytes Lymphocytes are divided into two specialized groups, dependent on where they mature: ○ B-Lymphocytes (B-cells): Mature in bone marrow and produce Y-shaped antibodies ○ T-Lymphocytes (T-cells): Mature in thymus gland (near the heart) and signal an attack from foreign invaders Antigens & Antibodies Antigens: Molecules that are found on surface of cells and on pathogens ○ Provide identification in order for T and B cells to recognize foreign antigens Antibodies: Y-shaped proteins and attaches to specific antigens because they have similar shapes Antigen-antibody complex makes invader more visible to wandering macrophages, which engulf bacteria Antibodies can bind to toxins, changing shape and preventing them from entering cells ○ Also work on viruses in the same manner However, viruses quickly mutate and prevent same antibodies from working for very long HIV can actually “hide” inside T-cells that are supposed to signal its presence Recognizing Antigens When an invader is destroyed by a macrophage, its antigen goes to the macrophage surface Macrophage then couples with helper T-cells, which recognizes antigen ○ Releases chemical signal that stimulates macrophages, B-cells, and T-cells into action Chemical causes B-cells to divide and start to produce antibodies Recognizing Antigens Helper T-cells also activate killer T-cells ○ Killer T-cells destroy invading cells and body cells that are infected by viruses by puncturing their cell membrane ○ Killer T-cells may be activated indirectly by chemical signals from helper T-cells or directly by presence of invading pathogen with associated antigen Once infection is fought off, suppressor T-cells signal immune system to shut down ○ Ensures normal tissue isn’t destroyed Phagocytes clean up any dead/injured B and T-cells that remain Not all T-cells respond to invading antigens the first time they are exposed to them ○ They remain in bloodstream as memory T-cells that are able to act quickly if antigen invades again Blood Types Blood transfusion: Transfer of blood from one person in blood of another Different blood groups: Different groups of red blood cell antigens ABO system: Presence of Type A and B antigens on red blood cells, determines blood type Blood Groups - How They Work A blood type: “A” version antigen on surface of red blood cell B blood type: “B” version antigen on surface of red blood cell AB blood type: Both O blood type: No antigen ○ Type A blood: Anti-B antibodies in plasma ○ Type B blood: Anti-A antibodies in plasma ○ Type O has both Agglutination: Clumping of red blood cells that occur when incompatible blood types are mixed Blood Groups - How They Work Blood Types Antigen Antibodies Receive blood from... A A B A, O B B A B, O AB both none AB, A, B, O O none both O Rhesus (Rh) Factor Second antigen found in red blood cells People can be Rh+ or Rh- (either antigen is present or not) Rh- individuals don’t have antigens ○ But may make them when exposed during blood transfusion/pregnancy Rhesus Factor and Pregnancy If baby receives Rh factor from father (ex. Rh+), but mom is Rh-, baby’s blood will come to contact with mother’s immune system at birth As result, mother will start to produce antibodies against Rh+ blood Any subsequent fetuses that are Rh+ will experience clumping of blood in their veins due to their mother’s antibodies ○ Treatment: Blood transfusion for the child Video - Immune System https://www.youtube.com/watch?v=lXfEK8G8CUI