Bios 255 Lymphatic System Study Notes

LYMPHATIC SYSTEM -Disease resistance - Innate immunity- passive, present at birth and includes defense mechanisms that provide general protection against invasion by a wide range of pathogens -Adaptive- involves activation of specific lymphocytes that combat a particular pathogen or other foreign substance (carried out by lymphatic system) Passive Immunity Active Immunity Natural Temporary, antibody based, transplacental, colostrum, milk IgG, IgA Lifetime, strong T cell, increase morbidity and mortality, actual infections Artificial Temporary, antibody based (IgG, IgM), antivenoms, gamma-globulin injections Lifetime, strong B cells, sometimes T cells, decrease morbidity and mortality, vaccinations -Lymphatic system- consists of several structures and organs that contain lymphatic tissue, bone marrow (flat bones and head of femur), and lymph fluid within lymphatic vessels -Disease resistance- phagocytosis, T and B lymphocyte, lymphatic vessels, spleen, lymph nodes, thymus -Functions- drain interstitial fluid, transport dietary fats, carry out immune response -Lymphatic vessels begin as capillaries which are closed on one end -Lymphatic capillaries are located between cells of many tissues -Formation and flow of lymph-interstitial fluid lymph capillaries vessels lymph trunks lymph ducts subclavian veins - Lymph trunks and ducts- from the lymphatic vessels, lymph passes through lymph nodes and into trunks. Lymph trunks include lumbar, intestinal, bronchiomediastinal, subclavian, and jugular trunks. Lymph trunks then merge to form either the thoracic duct or the right lymphatic ducts. -Primary lymphatic organs are organs where immune cells become immunocompetent (re bone marrow and thymus) -Secondary lymphatic organs and tissues include lymph nodes, spleen, and lymphatic nodules -Lymphatic nodules are masses of lymphatic tissue that are not surrounded by a capsule  They are scattered throughout the lamina propria of mucous membranes lining the gastrointestinal, urinary, and reproductive tracts and the respiratory airways  Lymphatic nodules in these areas are also referred to as mucosa-associated lymphatic tissue (MALT) -Innate immunity refers to a wide variety of body responses that serve to protect us against invasion of a wide variety of pathogens and their toxins -We are born with this kind of immunity -Two lines of defense:  Skin and mucous membranes  Internal defenses -Skin and mucous membrane -Mechanical defenses  Skin, mucous membranes, tears, saliva, mucus, cilia, epiglottis, urine flow, defecating, vomiting -Chemical defenses  Sebum, lysozyme, gastric juice -Adaptive immunity is the ability of the body to defend itself against specific invading agents  Antigens are substances recognized as foreign that provoke immune responses -Adaptive immunity has both specificity and memory and is divided into 2 types 1. Cell-mediated 2. Antibody-mediated -For an immune response to occur, B cells and T cells must recognize that a foreign antigen is present.  B cells can recognize and bind to antigens in lymph, interstitial fluid, or blood plasma  T cells only recognize fragments of antigenic proteins that are processed and presented in a certain way -In antigen processing, antigenic proteins are broken down into peptide fragments that associate with MHC molecules -The antigen–MHC complex is then inserted into the plasma membrane of a body cell  This process is called antigen presentation