Immunity - BISC 220 3/29/10 1 Lymphatic System &...

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BISC 220 1 3/29/10 Introduction Immunity: o Defends against infection by viruses, bacteria, fungi, and parasites o Destroy and recycle worn out cells o Identify and destroy cancer cells When it doesn’t work… o Allergies- exaggerated immune responses to mostly harmless stimuli o Autoimmune diseases- immune system attacks its own cells o Immunodeficiency diseases- when the immune system itself is deficient o Limits tissue/organ transplants Types of immunity o Innate (nonspecific, active all the time), Acquired (specific, slight delay) Lymphatic System Lymph- excess fluid that leaves through capillaries, drains into blind-ended lymphatic capillaries, collects into lymphatic vessels, then lymph veins which converge on lymph nodes o Drains into lymphatic ducts, which drain into the thoracic duct where lymph drains back into the blood Lymph nodes o Has physical barriers that filter foreign bacteria, cellular debris o Home to vast numbers of cells of the immune system (lymphocytes, macrophages, etc.) o Possible threats in the region of a body drained by a set of lymph vessels and passing through are lymph nodes are brought to the immune system (conducting surveillance largely from lymph nodes) Red bone marrow included in the lymphatic system o T lymphocytes are born in the bone marrow, migrate to the thymus where they mature and achieve full capability to respond
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BISC 220 2 3/29/10 Spleen has vessels and spaces where blood pools, effector cells of the immune system residing there conduct surveillance of RBC, pick out damaged cells and destroy them o Red bone marrow reproduces RBC o RBCs last about 3-4 months, continual recycling Typical response to a hemorrhage would be vasoconstriction of leg veins to put blood back in circulation to help build up blood pressure and blood volume, also constriction of smooth muscle in the spleen to squeeze blood out Adenoids- lymph from upper nasopharynx drain through Tonsils- lymphoid tissues that serve defensive function for pharynx Peyer’s patches in small intestine, lymphoid tissue serve in immune defense of body at that location of the body (huge, scattered throughout intestine) Appendix is possibly a lymphoid organ that helps in immune defense Some cells in the lymph nodes have the ability to leave and travel through blood and lymphatic system (highways for immune system effector cells) Overview of Innate Immunity Inherited, born with it, rapidly acting, requires no activation, no memory of prior exposure includes barrier, chemical, and cellular defenses nonspecific Barrier Defenses Skin o Stratified squamous (flat) epithelium o Stratum corneum (outer layer) is impervious [cellular outer layer] Give rise to new skin cells, which are pushed to the surface, by the time the cells get to the outside, they are dead, filled with impervious keratin protein and protect the skin from infiltration Keratin- tough protein, mechanical strength, barrier
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This note was uploaded on 09/28/2010 for the course BISC 220 taught by Professor Mcclure during the Spring '09 term at USC.

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Immunity - BISC 220 3/29/10 1 Lymphatic System &...

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