lymphatic system

• clear fluid derived from blood plasma • contains water, immune cells and sometimes fats

• blood leaks fluid into tissues - becomes interstitial fluid • lymph capillaries absorb this fluid - now called lymph • lymph vessels move lymph towards the heart • lymph nodes filet it along the way • fluid returns to the blood via right lymphatic duct and thoracic duct

• a molecule that triggers an immune response • found on the surfaces of bacteria, viruses, pollen, toxins • foreign antigens trigger immunity • self antigens normally do not

• a protein made by B cells that binds to antigens • neutralize pathogens • agglutinate = clump them • precipitate = make them fall out of solution • opsonize = mark for destruction • activate compliment system

the lymphatic system also helps maintain body fluid balance and transports fats

• blood capillaries push fluid into tissues • lymph capillaries collect excess fluid and send it back to blood

• small intestine has special lymph vessels called lacteals • they absorb fats and package them as chylomicrons • this gives lymph a milky appearance called chyle

are lymph vessels inside the villi of the small intestine. They absorb fats from your food.

fat absorption + fluid balance + immunity

bone marrow + thymus called primary because this is where lymphocytes are made and mature

stem cells become - B cells - Nk cells - immature T cells (but they don’t mature here)

immature T cells leave the bone marrow and go to thymus mature into - helper T cells - cytotoxic T cells - memory T cells - regulatory T cells

• B and T cells travel thru bloodstream to secondary lymphatic organs like • lymph nodes • spleen • tonsils • there they wait for antigens • once activated they become “effector cells”