immune system

• non specific • born with it • physical Barries like skin and mucous membranes • chemical barriers like acid stomach pH, enzymes like lysozyme • cellular defenses like phagocytes, natural killer cells

• when your first exposed to an antigen, your body learns it and makes a specific response • next time you see it, MUCH faster response

T cells - mature in thymus - handle cell mediated immunity (kill infected cells) B cells - mature in bone marrow - handle humoral immunity (make antibodies)

• helper T cells • Cytotoxic (killer) T cells • Memory T cells • regulatory T cells

• activate other immune cells • needed for activating B cells and cytotoxic T cells

• destroy infected or abnormal cells • release enzymes to kill them

• remember the antigen • respond quickly on second exposure

• prevent the immune system from attacking your own body • help stop the response when the infection is gone

• plasma cells • memory B cells

make and release antibodies

• remember the antigen • produce antibodies quickly during the next infection

• neutrophils • macrophages • monocytes • NK cells • eosinophils • basophils • mast cells • dendritic cells

• most common WBC • first responders • eat bacteria

• big phagocytes • eat pathogens and dead cells • present antigens to T cells

• become macrophages when they enter tissues

• kill virus infected cells and cancer cells

• fight parasites • help with allergies

• release histamine during allergic reactions

• similar to basophils • found in tissues and basophils are found in blood • release histamine - inflammation

• antigen presenting cells • bridge between innate and adaptive immunity • activate T cells • scout antigens and show them to T cells

• bone marrow • thymus • spleen • lymph nodes • MALT

• this is where all blood cells are made, including immune cells • it is also where B cells mature • bone marrow = birthplace + B cell training center

• located above the heart • this is where T cells mature • shrinks in adulthood

• filters old red blood cells • contains many macrophages and lymphocytes • helps clean pathogens from blood • spleen = blood filter + immune cell storage