THE LYMPHATIC SYSTEM AND IMMUNITY Chapter 15

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. FUNCTIONS OF THE LYMPHATIC SYSTEM Lymph fluid acts as intermediary between blood, capillaries, and tissues Lymph vessels transport tissue fluid back into circulatory system Lymph nodes produce lymphocytes and filter harmful bacteria

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. FUNCTIONS OF THE LYMPHATIC SYSTEM Spleen produces lymphocytes and monocytes, acts as a reservoir for blood, and recycles red blood cells Thymus gland produces T- lymphocytes for immune system

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. LYMPH Lymph diffuses from capillaries into tissue spaces Lymph acts as an intermediary between blood in capillaries and tissues Lymph carries digested food, oxygen, and hormones to cells

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. LYMPH VESSELS Lymph vessels accompany and are similar to veins They are in almost all tissues and organs that have blood vessels Lymph only travels in direction from body organs to the heart

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. LYMPH VESSELS 2 large main lymphatics –Thoracic duct (left lymphatic duct) Receives lymph from left side of head, neck, abdominal area, and lower limbs –Right lymphatic duct Circulates lymph from right arm, right side of head, and upper trunk to the superior vena cava

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. LYMPH NODES Lymph nodes provide sites for lymphocyte production and screen harmful substances from the lymph Bacteria and other harmful substances in large quantities may injure the lymph node Adenitis - swelling in lymph gland

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. LYMPH NODES

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. TONSILS Tonsils are masses of lymphatic tissues capable of producing lymphocytes and filtering bacteria Three pairs of tonsils –Palatine –Adenoids –Lingual

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. SPLEEN The spleen is a saclike mass of lymphatic tissue that forms lymphocytes and monocytes The spleen filters blood that passes through it, destroying old or fragile red blood cells The spleen stores large amounts of red blood cells

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. THYMUS GLAND The thymus’s function is to produce lymphocytes called T-lymphocytes The thymus is also an endocrine gland because it secretes a hormone called thymosin that stimulates the production of lymphoid cells

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. DISORDERS OF THE LYMPH SYSTEM Lymphadenitis - enlargement of the lymph nodes that occurs when infection is present Hodgkin’s disease - form of cancer of lymph nodes Infectious mononucleosis - caused by Epstein-Barr virus

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. IMMUNITY Immunity is the body’s ability to resist invaders and disease –Acquired immunity - reaction to exposure of invaders –Passive acquired immunity - borrowed immunity from another person’s blood that produces immunity immediately

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. IMMUNITY –Active acquired immunity Natural acquired immunity results from having had and recovering from disease Artificial acquired immunity is the result of inoculation with vaccine, antigen, or toxoid –Immunization is increasing the resistance to infection through artificial means

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. IMMUNITY Autoimmunity –Occurs when a person’s own immune system targets normal cells, tissues, and organs of person’s own body –Causes range from genetics to viruses to sunlight exposure

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. IMMUNITY Hypersensitivity –Body’s immune system fails to protect itself against foreign material –Antibodies irritate certain body cells –Allergen - antigen causes allergic responses Anaphylactic shock - severe, often fatal allergic reaction

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. AIDS/HIV Acquired - disease is not inherited Immune - body’s natural defenses Deficiency - lacks cellular immunity Syndrome - diagnosed from sets of diseases or conditions present

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. AIDS/HIV Human immunodeficiency virus (HIV) destroys T4-lymphocyte cells without causing symptoms Opportunistic infections arise Three outcomes of HIV infection: –AIDS –AIDS-related complex (ARC) –Asymptomatic infection

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. AIDS/HIV Transmission of AIDS –Sexual contact with infected partner –Sharing hypodermic needles among IV drug users –In utero or at birth of infected mother –Transfusion of blood

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. AIDS/HIV Screening tests for HIV/AIDS –There are two antibody tests Enzyme-linked immunosorbent assay (ELISA) - detects antibodies for AIDS but not the virus Western blot is the follow-up to confirm ELISA results

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. AIDS/HIV Symptoms of HIV/AIDS –Flu-like symptoms –Fever –Headache –Malaise –Enlarged lymph glands

© 2004 Delmar Learning, a Division of Thomson Learning, Inc. AIDS/HIV There is no cure for AIDS yet certain drugs are used to slow the virus Transmission is prevented by following the CDC’s Standard Precautions