D3.3 - The Lymphatic System and Immunity (Updated 2024) PDF

D3.3 - The Lymphatic System and Immunity I can… Describe and explain the function of the lymphatic system List the main components of the human defence system and describe their role in immunity (skin, macrophage, helper T cell, B cell, killer T cell, suppressor T cell, memory T cel...

D3.3 - The Lymphatic System and Immunity I can… Describe and explain the function of the lymphatic system List the main components of the human defence system and describe their role in immunity (skin, macrophage, helper T cell, B cell, killer T cell, suppressor T cell, memory T cell) Describe the ABO and Rh blood groups on the basis of antigens and antibodies The Lymphatic System The blood (specifically, white blood cells) also plays an important role in immunity ○ However, the blood does not work alone… The lymphatic system acts in conjunction with the circulatory system to protect the body against infection The Lymphatic System Lymphatic system: Network of vessels, glands, and nodes spread throughout body, closely associated with the capillaries of the cardiovascular system Collects lymph fluid, which is which is similar to the composition of blood plasma (“interstitial fluid”) Lymph helps to maintain the balance of fluids in the body, bathing cells in interstitial fluid as it mixes with general blood circulation 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 Important Terms Antigen: A substance, usually protein, that stimulates the formation of an antibody Antibody: A protein formed with blood that reacts with an antigen Pathogen: An organism causing disease to its host The Lymphatic System and Immunity Lymph nodes are where white blood cells mature ○ They also contain macrophages (a type of white blood cell that traps and destroys bacteria) Infections often lead to an increase in the number of macrophages ○ As a result, lymph glands may swell when you are sick Immunity (First Line of Defense) Physical and chemical barriers of the body. Immunity (Second Line of Defense) Involves non-specific white blood cells known as phagocytes, which act to engulf and destroy foreign pathogens in the bloodstream Also referred to as the “inflammatory response”, as the action of phagocytes often results in swelling and fever There are three types of phagocytes: Immunity (Second Line of Defense) Phagocytes such as macrophages, neutrophils, and monocytes destroy harmful pathogens through a process known as phagocytosis (ingesting bacteria) Immunity (Third Line of Defense) Also known as antibody-mediated immunity A number of specific white blood cells or “lymphocytes” target pathogens according to the specific markers they present Different types of lymphocytes include: ○ B-cells ○ T-Cells ○ Antibodies (note: antibodies are actually a type of protein, not a white blood cell) T-Cells Helper T-cells analyze pathogens after they have been broken down by phagocytes and recruit B-cells to help identify the foreign particles Killer T-cells recognize cells infected by a virus and/or cancerous human cells and destroy them Suppressor T-cells monitor killer T-cells to make sure they do not destroy healthy tissues B-Cells B-cells are recruited to the site of phagocytosis by T-cells, where they become activated and divide into two different types of B-cells: memory B-cells and plasma cells ○ Memory B-cells display antibodies (proteins) that match the antigens (proteins) presented by that particular pathogen They remain in the bloodstream so that if they ever encounter that pathogen again, they can quickly call a phagocyte to the scene. ○ Plasma cells produce antibodies that recognize and attach to the antigens of specific pathogens, essentially slowing the pathogen down and marking it for destruction by phagocytes Antibodies remain in the bloodstream so that next time the pathogen enters the bloodstream, phagocytes can quickly destroy it 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 Antibodies Antibodies are proteins in the bloodstream that recognize the antigens displayed by foreign particles and trigger a series of events to quickly neutralize or destroy them Antibodies specific to different pathogens are generated after white blood cells destroy said pathogens through phagocytosis Over time, exposure to various foreign substances leads to the development of an immune system unique to each individual Vaccines 1. Every vaccine is different. However, they are all based on the principle of providing people with antibodies against specific antigens. 2. Most vaccines involve injecting a “deactivated” version of a pathogen into your body. This means that the pathogen cannot reproduce and infect your tissues, but it does contain the antigen markers on it’s cell surface. 3. When your body detects the presence of the deactivated pathogen, it still launches a full-scale immune response, even though there is no actual threat. This is why people often develop a fever or feel “sick” after receiving a vaccine. 4. Once your body detects the pathogen, Helper T-cells recruit B-cells, which differentiate and start producing antibodies against that pathogen’s antigens. 5. Once you have those antibodies, you will be able to fight off the “real pathogen” more easily should it ever try to infect your cells. This is what gives you “immunity” against that pathogen. 6. Many vaccines require a booster shot after a few years, as these antibodies (which are just proteins) tend to break down over time. This is also why elderly people tend to have a weaker immune system compared to younger individuals. 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 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 The second antigen found in red blood cells People can be Rh+ or Rh- (either the 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 Allergies Allergies occur when the immune system mistakenly recognizes harmless foreign particles as serious threats Launches immune response, which causes sneezing, runny nose, and watery eyes Antihistamines can block the effect of histamines and bring relief to allergy sufferers Acquired Immune Deficiency Syndrome “AIDS” is caused by the Human Immunodeficiency Virus (HIV) Discovered in 1983, HIV is transmitted through the sharing of bodily fluids (ex. unprotected sex or blood-blood contact) Specifically targets and kills T-cells, thereby preventing your immune system from working properly The HIV virus itself therefore doesn’t kill you; it cripples your immune system Video - Immune System https://www.youtube.com/watch?v=lXfEK8G8CUI