Lymphatic system

• The functions of the Lymphatic System include fluid balance, fat absorption, and defense.
• The Lymphatic System and Lymph Drainage are accessed through the lymphatic capillaries.
• Lymph is a fluid that enters lymphatic capillaries composed of water and some solutes.
• Lymphocytes are a component of the Lymphatic System.
• Lymphatic vessels resemble small veins and are located where lymphatic capillaries join.
• One-way valves are located in lymphatic vessels.
• Active immunity is of two types: natural (antigens are introduced through natural exposure) and artificial (antigens are deliberately introduced in a vaccine).
• Passive immunity: Immunity is transferred from another person or an animal.
• Passive immunity is of two types: natural (Antibodies from the mother are transferred to her child across the placenta or in milk) and passive (antibodies produced by another person or an animal are injected).
• The right lymphatic duct collects lymph from the right upper limb and right head, neck, chest and empties into the right subclavian vein.
• The Thoracic duct collects lymph from the remaining lymphatic vessels which do not enter the right lymphatic duct and empties into the left subclavian vein.
• Lymphatic organs include the tonsils, lymph nodes, spleen, thymus gland, and lymphatic capillaries.
• Tonsils include palatine tonsils on each side of the oral cavity, pharyngeal tonsils near the internal opening of the nasal cavity (adenoid), and lingual tonsils on the posterior surface of the tongue.
• Lymph nodes are rounded structures that vary in size and are located near lymphatic vessels in the groin, armpit, neck.
• Lymph moves through the immune system and is activated (lymphocytes produced) if foreign substances are detected.
• The spleen is a size of a clenched fist and is located in the abdomen where it filters blood, detects and responds to foreign substances, destroys old red blood cells, and serves as a blood reservoir.
• The thymus gland is a bilobed gland located in the mediastinum behind the sternum where it produces and matures lymphocytes.
• Immunity is the ability to resist damage from foreign substances and can protect against microbes, toxins, and cancer cells.
• Innate immunity is present at birth and is the defense against any pathogen, accomplished by physical barriers, chemical mediators, cells, and inflammatory response.
• B cells and T cell though circulation enter lymph node.
• Target cell attaches to the cytotoxic T cell receptor that has MHC class 1 molecule bonded processed antigen, CD8, and T-cell receptor.
• The daughter B cells produced can either become plasma cells (antibodies) or memory B cell.
• Acquired adaptive immunity is of two types: active immunity and passive immunity.
• The first exposure to primary response takes longer response time (3 to 14 days) while second exposure to secondary response takes shorter response time (hours to a few days) in antibody production.
• Active immunity: Immunity is provided by the individual’s own immune system.
• Activation of a cytotoxic T cell by antigen on the surface of a cell yields cytotoxic T cells and memory T cells.
• Antibodies initiate the release of inflammatory chemicals such as mast cell or basophil releases chemicals that leads to inflammation.
• The constant regions of light and heavy chains with complement-binding site and site for binding of macrophages, basophils, and mast cells along with variable regions of light and heavy chains make up the antibody structure.
• Antibody binding inactivates the antigen.
• Helper T cells are stimulated to divide again, and they can stimulate B cells or effector T cells, or they can become memory helper T-cell.
• Antibodies bind several antigen together and activate the complement cascade that leads inflammation, chemotaxis, and lysis.
• Antibodies facilitate phagocytosis by macrophages.
• Helper T cell provides interleukin-2 to cytotoxic T-cell that yields 2 daughter cells.
• Cytotoxic T cells releases cytokines that produces inflammation, initiates phagocytosis, and activates T cells.
• Cytotoxic T cells also kill cells on contact (target cell lyses).
• Bacteria are contained, destroyed, and phagocytized when the bacteria are gone the tissue repairs when the bacteria remain, additional chemical mediators are activated, and again chemical mediators are released.
• Physical barriers such as the skin and mucous membranes act as barriers to pathogens and toxins, and tears, saliva, urine wash away pathogens and toxins.
• Chemical mediators are chemicals that can kill microbes and prevent their entry into cells, with Lysozyme found in tears and saliva to kill bacteria, and Mucous membranes preventing entry of microbes.
• Histamine promotes inflammation by causing vasodilation, and Interferons are proteins that protect against viral infections by stimulating surrounding cells to produce antiviral proteins.
• Lymphatic System functions include lymph formation and movement, lymph node, spleen, and thymus gland overview, and an overview of the lymphatic system.