Anatomy and Physiology March 23rd and 24th, 2015 The Lymphatic and immune systems

Schedule for Remainder of the Quarter 3/23 and 3/24 Lymphatic and immune system 3/25 and 3/26 3/27 Review Cardiovascular, blood, lymphatic and immune system 3/30 and 3/31 Quarter 3 final exam 4/1 and 4/2 Documentary “Bad Blood”

Lymphatic System Collection of cells and biochemical that travel in lymphatic vessels and the organs and glands that produce them Assists in circulating body fluids Closely associated with the cardiovascular system Transports excess fluid from tissues back into the blood Lacteals absorb digested fats and transport them to the venous circulation

Lymphatic system organization Lymphatic capillaries – collect fluid from tissues Lymphatic vessels – similar to veins, contain valves, lead to lymph nodes Lymphatic trunks – drain fluid from lymphatic vessels

Lymphatic system organization cont… Collecting ducts – final location before being emptied into venous system Thoracic duct - Collects from lower body, abdomen, left upper limb, left side of thorax, head, neck Right Lymphatic Duct - Collects from right side of head and neck, right upper limb and right thorax

Movement of Lymph Primarily flows due to pressure caused by skeletal muscles contracting and breathing Blockage of Lymphatic pathways or removal of lymphatic vessels can result in fluid buildup in the area know as edema

Lymph Nodes Located all throughout the body along the lymphatic pathways except for in the central nervous system Contain large numbers of lymphocytes (b and t cells) and macrophages Tonsils are partially encapsulated lymph nodes

Lymph Nodes Functions Filtering potentially harmful particles from lymph before returning it to the blood stream Monitoring body fluids (immune surveillance) provided by lymphocytes and macrophages Site of lymphocyte production

Other Lymphatic Organs Thymus Soft gland that Is large during infancy but drastically shrinks through adulthood Produces some mature t-cells Spleen Largest lymphatic organ White pulp – similar to lymph nodes, packed with lymphocytes Red pulp – contains RBC’s, plus lymphocytes and macrophages Responsible for filtering the blood, removing and recycling old RBC’s

Questions???

The Immune System Protection against pathogens – disease causing agents such as viruses, bacteria, fungi and protozoans Additional protection against cancer cells to some extent

Innate immunity (non-Specific) Mechanical barriers – skin, mucous membranes (1st Line of Defense) Chemical Barriers – enzymes, gastric juice, salt, sweat, interferons, Complement Natural killer cells – lymphocytes that defend against viruses and cancer cells Inflammation – redness, swelling, heat, pain; attracts phagocytes and fibrinogen Phagocytosis – neutrophils, monocytes and macrophages engulf and destroy Fever – increased temperature makes environment inhospitable and increases activity of phagocytes

Acquired immunity (Specific) Antigens Components located on cell surfaces Before birth, cells identify certain molecules as “self” Non-Self or foreign antigens are detected

T-Lymphocytes or t-cells Originates in Bone Marrow Differentiates in Thymus 70-80% of Lymphocytes Provides cellular immunity by directly interacting with antigens or antigen bearing agents to destroy them Three Main Types Helper – stimulate b-cells to produce antibodies Cytotoxic – bind to antigen bearing cells and destroy them Memory – remain inactive until subsequent exposure to same antigen

B-Lymphocytes or b-cells Originates and differentiates in bone marrow 20-30% of lymphocytes Provides Humoral immune response by interacting indirectly producing antibodies that destroy the antigens or antigen bearing agents Becomes activated when encountering an antigen or helper t-Cell associated with the same antigen Two main types Memory – remain inactive until subsequent exposure Plasma – produce antibodies or immunoglobulins Can produce up to 2000 antibodies per second

Antibodies (Ab) IgG AKA immunoglobulins (Ig) Proteins produced by plasma cells in response to a specific antigen (Ag) Antibodies [Ab] frequently measured as a diagnostic tool Serology High IgM can signal current primary infection High IgG can signal current secondary infections IgG

5 subclasses of Igs: IgG: main Ab (75%) in serum; + main Ab during 2o response (passive immunity from mother) IgA: main Ab in external secretions including breast milk IgE: main Ab in allergic reactions (associated with histamine) IgM: Ab on virgin B-cells; + main Ab during 1o response, anti-a and anti-b are this type IgD: Ab on virgin B-cells, important for activation

Immunity can be naturally or artificially acquired Immunity can be naturally or artificially acquired. Also, immunity can be active or passive. Active immunity lasts for a long time. This is often many years to a lifetime. In active immunity the body makes its own antibodies. Passive immunity is short term. It typically lasts for just a few months. In passive immunity antibodies are borrowed from someone else. A natural way to get active immunity is have a disease and survive. After that time you will make antibodies to the pathogen. A natural way to get passive immunity is when antibodies pass from the mother to the fetus across the placenta. An artificial way to get active immunity is to be vaccinated with dead or weakened pathogen. An artificial way to get passive immunity is to receive an injection of antibodies made by someone else. Gamma globulin is the portion of serum that contains antibodies.  

Allergic Reactions Immune response to non harmful substance called allergen Delayed reaction – result from repeated exposure Immediate reaction Occurs within minutes Overproduction of ige antibodies Mast cells and basophils release histamine Causes inflammation, smooth muscle contraction and increased mucous production

Transplantation and tissue rejection MHC antigen on cell surfaces must match for proper transplantation Immunosuppressive drugs reduce the risk Graft vs. host disease Cells in implanted bone marrow attack host body

Autoimmunity Type1 diabetes, rheumatoid arthritis and systemic lupus erythematosus Antibodies and Cytotoxic t-cells see “self” antigens as “non-self” and attack