lymphatic system

• The Integumentary System includes the Lymphatic System.
• Immunity or Resistance is the ability to ward off damage or disease through our defenses.
• There are two types of immunity: Innate or nonspecific immunity, which is present at birth, and Adaptive or specific immunity, which is acquired through experience.
• The Lymphatic System consists of lymph, lymphatic vessels, structures and organs containing lymphatic tissue, red bone marrow.
• The functions of the Lymphatic System include drain excess interstitial fluid, transport dietary lipid, and carry our immune responses.
• Components of the Lymphatic System include lymphatic vessels and lymph circulation, lymphatic capillaries, lymph trunks and ducts, and lymph nodes.
• Infected cell displays antigen next to MHC-I.
• Post action: APCs migrate from tissue via lymphatic vessels to lymph nodes.
• Antigen-presenting cells (APCs) include dendritic cells, macrophages and B cells.
• After processing an antigen, APCs migrate to lymphatic tissue to present antigen to T cells.
• APCs ingest antigen, process, place next to MHC-II molecule in plasma membrane, and present to T cells.
• T cells bind with antigen fragment MHC complex to trigger cell mediated/antibody mediated immune response.
• Exogenous antigens are present in fluid outside body cells.
• The pathway of antigen presentation depends on whether the antigen is outside or inside the body cells.
• Endogenous antigens are antigens inside body cells.
• The location of antigen presenting cells is the place where antigens like to penetrate, such as the skin, where Langerhans cells are dendritic cells.
• B cells can recognize and bind to antigens in lymph, interstitial fluid, or blood plasma.
• Antigen presentation involves inserting the antigen-MHC complex into the plasma membrane.
• T cells only recognize fragments of antigens that are processed and presented in a certain way.
• Mucous membranes of respiratory, gastrointestinal, urinary, and reproductive tracts, as well as lymph nodes, are also locations for antigen presenting cells.
• Antigen processing involves breaking down antigenic proteins into peptide fragments and associating them with MHC molecules.
• Antigen presenting cells include dendritic cells, macrophages, and B cells.
• Lymphatic vessels begin as lymphatic capillaries, which are closed at one end, unite to form large lymphatic vessels, and resemble veins in structure but thinner walls and more valves.
• Lymphatic capillaries have a unique one-way structure that permits interstitial fluid to flow in but not out, and anchoring filaments pull openings wider when interstitial fluid accumulates.
• Lymph trunks and ducts are vessels that unite to form lymph trunks, with principal trunks being the lumbar, intestinal, bronchomediastinal, subclavian and jugular, and pass from lymph trunks into two main channels (thoracic and right lymphatic ducts) before draining into venous blood.
• Lymphatic vessels contain valves and the same two “pumps” aiding venous return also used in skeletal muscle pump and respiratory pump.
• The Lymphatic System has a relationship with the Cardiovascular System.
• Lymphatic nodules are not surrounded by a capsule and are scattered throughout the lamina propria of mucous membranes lining the GI, urinary, and reproductive tract.
• Mucosa-associated lymphatic tissue (MALT) of the respiratory tract is also included in the lymphatic system.
• Interferons are produced by lymphocytes, macrophages, and fibroblasts infected by viruses and prevent the replication of neighboring uninfected cells.
• Chemical barriers in the skin include sebaceous (oil) glands that secrete sebum, a protective film and acid, and gastric juice, vaginal secretions, and defecation and vomiting that expel microbes.
• Iron-binding proteins inhibit the growth of bacteria by reducing available iron, with transferrin in blood and tissue fluids, lactoferin in milk, saliva, mucus, ferritin in liver and spleen, and hemoglobin in red blood cells.
• Physical barriers in the skin include the epidermis, which is closely packed and keratinized, and mucous membranes, which trap microbes and foreign substances.
• Most lymphatic nodules are small and solitary, but some are larger, such as tonsils, Peyer’s patches, and appendix.
• The first line of defenses in the innate immune system are the skin and mucous membranes, which provide both physical and chemical barriers.
• The second line of defenses in the innate immune system are internal defenses, which include antimicrobial substances such as interferons and complement.
• Complement proteins in blood plasma and plasma membranes enhance certain immune reactions, cause cytolysis of microbes, promote phagocytosis, and contribute to inflammation.
• Nose hairs and cilia of the upper respiratory tract also contribute to the physical barriers by trapping and filtering.
• In the killing stage of phagocytosis, the digestive enzymes in the phagocyte lysosome digest the microbe in a phagolysosome.
• Inflammation has 3 basic stages: vasodilation and increased blood vessel permeability, emigration, and tissue repair.