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Chapter 15 THE LYMPHATIC SYSTEM AND IMMUNITY 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 Tlymphocytes 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 © 2004 Delmar Learning, a Division of Thomson Learning, Inc.