Lymphatic System

• The lymphatic system consists of cells that have specific functions and play crucial roles in maintaining fluid balance, interstitial fluid homeostasis, and defense against disease.
• The lymphatic system consists of three lines of defense against pathogens: natural killer cells, T lymphocytes, and macrophages.
• Specific immunity differs from nonspecific defenses.
• The functions of the lymphatic system include fluid balance, interstitial fluid homeostasis, and defense against disease.
• Lymph is fluid derived from blood.
• Lymphatic vessels contain pacemaker cells in their smooth muscle walls, which contract to move lymph through the vessels.
• Surrounding muscles compress lymphatic vessels, moving lymph along.
• Thoracic pressure changes cause lymph to move.
• Natural killer cells are a type of nonspecific defense that destroy bacteria, fight against transplanted tissues, attack cells infected by viruses, and destroy cancer cells.
• Constant region of an antibody is responsible for activities of antibodies like activating complement or attaching to various kinds of WBCs.
• An antibody binds to an antigen and inactivates it.
• Antibodies bind several antigens together.
• An antibody can activate the complement cascade when an antigen binds to it.
• An antibody binds to a mast cell or a basophil and when an antigen binds to the antibody, it triggers the release of chemicals that cause inflammation.
• An antibody binds to an antigen and then to a macrophage, which phagocytizes the antibody and antigen.
• The primary response occurs when a B cell is first activated by an antigen.
• The B cell proliferates to produce plasma cells (antibody production) and memory cells.
• The secondary response occurs during later exposure to the same antigen.
• Memory cells divide rapidly to form plasma cells and additional memory cells.
• The secondary response produces a faster and greater response.
• T lymphocytes, also known as T helper cells, are vital for nonspecific defense and specific immunity by recognizing foreign pathogens and activating the cells to fight them.
• T cytotoxic cells directly kill cells infected by viruses and cancer cells in specific immunity.
• T memory cells remember pathogens that have been introduced to the body so that repeat exposure can be fought better.
• Lifelong problem, very difficult to treat
• Immunosuppressant drugs may help manage the progression of the disease
• Systemic Lupus Erythematosus
• Immunodeficiency Disorders
• Autoimmune Disorders
• Immunotherapy: treating disease by altering immune system function or directly attacking harmful cells
• Examples of immunotherapy include the administration of cytokines and the use of monoclonal antibodies to target tumors.
• Monoclonal antibodies are also used in checkpoint therapy.
• The ability of the lymphatic system to move fluid between the cardiovascular system and the lymphatic system does not decrease with age.
• Lymph will continue to leave blood vessels to nourish cells and remove their wastes.
• Lymph will also continue to carry the products of lipid digestion.
• The number of B cells in the lymphatic system remains relatively stable with age.
• The number of new T cells is affected as the thymus shrinks and much of the tissue is replaced with connective tissue.
• T cells in other lymphoid tissues can still clone themselves, but not as many will be made with each clone.
• The decrease in T helper cells could slow recognition of pathogens, which may be a reason that cancer is more prevalent in elderly people.
• Vaccinations might not offer as much protection as they did in younger age.
• The age-related changes to the immune system may have a positive effect if the elderly individual has allergies.