Lymphocyte Transport and Immunity PDF

Lymph Transport and Immunity Topic 17 Mader: Biology 8th Ed.  Outline Lymphoid Organs Immune System – Nonspecific Defenses Barriers Inflammatory Response – Specific Defenses Antibodies T Cells Active versus Passive Immunity Imm...

Lymph Transport and Immunity Topic 17 Mader: Biology 8th Ed.  Outline Lymphoid Organs Immune System – Nonspecific Defenses Barriers Inflammatory Response – Specific Defenses Antibodies T Cells Active versus Passive Immunity Immunity side effects  The Lymphatic System Consists of lymphatic vessels and the lymphoid organs. – Three main homeostatic functions: Lymphatic capillaries take up and return excess fluid to the bloodstream. Lacteals receive lipoproteins and transport them to the bloodstream. Helps defend body against disease. Mader: Biology 8th Ed. Lymph flows one way from a capillary to ever-larger lymphatic vessels and finally to a lymphatic duct, which enters a subclavian vein. Mader: Biology 8th Ed. Mader: Biology 8th Ed.  Lymphoid Organs Lymph Nodes - Capsule surrounding two distinct regions, cortex and medulla. – Lymphocytes congregate in cortex when fighting off a pathogen. – Macrophages concentrated in medulla - cleanse lymph. – Lymph nodes named for their location. Mader: Biology 8th Ed.  Lymphoid Organs Tonsils – Patches of lymphatic tissue located around the pharynx. First to encounter pathogens that enter via the nose and mouth. Spleen – Located in upper left region of abdominal cavity just beneath diaphragm. Cleanses blood Mader: Biology 8th Ed.  Lymphoid Organs Thymus Gland – Located along trachea behind the sternum in upper thoracic cavity. Produces thymic hormones. Red Bone Marrow – Origin for all types of blood cells. – Area of maturation for most white blood cells. Mader: Biology 8th Ed.  Immune System (Non specific) 1-Barriers to Entry Skin and mucous membranes lining respiratory, digestive, and urinary tracts serve as physical barriers (Upper respiratory tract lined by ciliated cells). 2-Inflammatory Reaction Damaged cells and mast cells release histamine and kinins. Capillaries dilate and become more permeable Neutrophils and monocytes migrate to the site of injury. –Neutrophils and mast cells phagocytize pathogens. –Monocytes differentiate into macrophages Mader: Biology 8th Ed. Mader: Biology 8th Ed.  Immune System (Specific Defense) An antigen is any foreign substance that stimulates the immune system to react. – Lymphocytes are capable of recognizing an antigen as they have antigen receptors. – B cells give rise to plasma cells which produce antibodies. – T cells directly attack cells that bear non-self proteins.  Immune System (Specific defense) 1-Antibody-Mediated Immunity (B lymphocytes) – Clonal selection theory states the antigen selects which lymphocyte will undergo clonal expansion and produce more lymphocytes. – If the same antigen enters the system again, memory B cells quickly divide and give rise to more lymphocytes capable of quickly producing antibodies. Mader: Biology 8th Ed.  Immune System (Specific defense) Clonal Selection in B Cells Mader: Biology 8th Ed.  Immune System (Specific defense) 2-Cell mediated immunity (T cells) -Types of T Cells Cytotoxic T Cells – Destroy antigen-bearing cells – Contain Perforins Helper T Cells – Regulate immunity by secreting cytokines. Mader: Biology 8th Ed.  Immune System (Specific defense) Clonal Selection in B Cells 2- Cytokines are released: signaling chemicals that stimulate various immune 1. T cells are activated by cells antigens presented by MHC (major histocompatibility complex) or (HLA in human) that are present on the membrane of certain WBCs. Mader: Biology 8th Ed. Cell-Mediated Immunity Mader: Biology 8th Ed.  Active versus Passive Immunity Active Immunity – Immunization Pathogens or pathogen products treated to remove virulence. Dependent upon presence of memory B cells and memory T cells capable of responding to lower doses of antigen.  Active versus Passive Immunity Passive Immunity -Passive immunity occurs when an individual is given prepared antibodies (immunoglobins) to combat a disease. -Short-lived -Newborns are often passively immune due to mother’s blood. Mader: Biology 8th Ed.  Immunity Side Effects Allergies – Hypersensitivities to substances that ordinarily would not harm the body. Immediate Response – IgE antibodies Delayed Response – Memory T cells Mader: Biology 8th Ed.  Immunity Side Effects Blood Type Reactions – ABO blood typing Two self antigens - A and B. If same antigen and active antibody are present in the blood, agglutination occurs. Mader: Biology 8th Ed.  Immunity Side Effects Tissue Rejection – Antibodies and cytotoxic T cells bring about destruction of foreign tissues in the body. Immune system is correctly distinguishing between self and non-self cells. Autoimmune Diseases – Cytotoxic T cells or antibodies mistakenly attack the body’s own cells. Mader: Biology 8th Ed.