Innate (means you are born with it) Immunity • Innate Immunity – The body’s first line of defense against any and all pathogens. • Skin is the first barrier • Pathogens encounter your body’s secretions. • Mucus, sweat, tears and saliva.
How Do Secretions Help? • Mucus traps pathogens that enter the respiratory and digestive tracks. The mucus is swallowed and the stomach’s acidic gastric juice (HCl) destroys the bacteria and toxins. • Sweat, tears and saliva all contain the enzyme lysozyme which breaks down the cell walls of some bacteria.
Response to the Damage to Body Tissue • Inflammation – occurs when bacteria or other pathogens damage body tissue. • Four Symptoms • Redness, Swelling, Pain and Heat • Symptoms not cause by pathogen but rather your body’s response to the pathogen.
What Kills Pathogens? • Phagocytes are White Blood Cells (WBC) that destroy pathogens by surrounding and engulfing the pathogen. • Phagocytes include: • Macrophages, neutrophils, and monocytes • Dead phagocytes and body fluid make pus. • Phagocytes cannot destroy viruses. • Anti-viral proteins called Interferon protect cells from viruses by interfering in the viral replication cycle.
Acquired Immunity • Acquired Immunity – The gradual build-up of resistance to a specific pathogen over time. • Occurs when the immune system recognizes antigens found on foreign substances and responds by producing antibodies against the foreign substance.
Lymphatic System • Lymphatic system helps defend the body and maintains homeostasis by keeping body cells constantly bathed in tissue fluid. • Tissue fluid collects in lymph vessels and is called lymph, which is filtered through lymph glands. • Lymph glands contain lymphocytes (WBC) and filters pathogens from the lymph.
Antibody Immunity • Occurs after innate and acquired immunity. • If an infection is not controlled and acquired immunity occurs, a type of lymphocyte called a T cell becomes involved. • Two types of T cells • Helper T cells – interact with B cells • Killer T cells – release enzymes directly into pathogens, causing them to lyse and die.
Antibody: B cell • B cells – lymphocytes that when activated become a plasma cell and makes antibodies, which are released into the bloodstream. • Memory B cells are B cells that remain in the bloodstream waiting for the same pathogen to come again. • Next time response is faster and without symptoms
Passive Immunity When antibodies are transferred from mother to unborn baby through the placenta. • From mother to baby through the breast milk. • Injecting the body with antibodies
Activity Immunity • Obtained naturally when a person is exposed to the pathogen. • If the person encounters the same virus at a later date, they are immune to it. • Vaccine is a weakened or dead pathogen that is injected into the body to cause an immune response.