The Human Immune System

First lines of defense tears antibacterial enzymes saliva antibacterial enzymes mucus linings traps dirt and microbes skin prevents entry stomach acid low pH kills harmful microbes “good” gut bacteria out compete bad

Pathogens = disease causing micro-organisms bacteria virus fungi protozoa parasites prion

Second lines of defense Involves white blood cells Non-specific response invading pathogens are targeted by macrophages (WBC) Specific response lymphocytes produce chemicals called antibodies that target specific pathogens

Phagocytes

The Phagocytes Phagocytes are the “soldiers” of the immune system They are responsible for, killing and digesting invading microbes. The process of swallowing microbes is known as phagocytosis.

Phagocytes Monocytes and macrophages Provide a non-specific response to infection

Phagocytosis The bacteria are digested by enzymes, and then absorbed by the phagocyte During infection, hundreds of phagocytes are needed. Pus is dead bacteria and phagocytes!

White Blood Cells

Lymphocytes Provide a specific immune response to infectious diseases. There are 2 types: - - T-cells - B-cells

B Cells & T Cells B and T cells perform specialized tasks B cells recognize antigens and then (as plasma cells) mass-produce specific antibodies Helper T cells coordinate the attack Killer T cells once activated, destroy virus-infected cells T cells “T” = Activated in Thymus

Antigen An antigen is any substance that creates an immune response, from a virus to a sliver. It can also be incorrectly identified as an invader (allergy response)

Bozeman: Immune System https://www.google.com/search?q=bozeman+immune+system&oq=bozeman+immune+system&aqs=chrome..69i57j69i60j69i65j69i59j69i61.3104j0j7&sourceid=chrome&es_sm=122&ie=UTF-8

When a virus or bacteria invade the body it is engulfed by a macrophage cell. The macrophage then signals T-cells to cause B-cells to multiply.

Macrophage

The B Cells get the message from the T-Cells, to produce antibodies which disable the invading bacteria.

Antibody Vs Antigen Antigen (the virus)

Immune System Can Attack Itself This is the case of autoimmune diseases: multiple sclerosis lupus some forms of arthritis diabetes allergies

Allergies The immune system thinks the foreign invader is harmful to you so it “reacts”

Anaphylaxis = Life Threatening Reaction

Interferon A small “natural” protein that acts against microbes – ESPECIALLY Viruses Until recently it was thought that IFN acted ONLY against viruses.

Defense & Repair: DVD – Online https://www. youtube. com/watch (KHS Library #824)

Neutrophils "eat" pathogens and send off distress signals. Monocytes are triggered to turn into pathogen-eating macrophages. Eosinophils attack parasites Basophils contain granules filled with histamine and other compounds related to allergies. The second set of cells — the lymphocytes — is slower to react. As the generalized campaign goes forward, a second set of specialized cells known as lymphocytes begins a more specific and enduring attack. The stars of this more adaptive immunological defense system — killer T cells, helper T cells, and B cells — work in concert to destroy infected cells. The B cells mature into plasma cells that generate highly specific antibodies capable of producing lasting immunity. T cells coordinate the immune system response. Any material that triggers this immune response is called an antigen.