Chapter 6 The Lymphatic and Immune System PDF

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Chapter 6 of EHS 115...

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● Functions Of The Lymphatic System ○ Three main functions: ■ Absorb fats and fat-soluble vitamins through the lacteals of the small intestine. ■ Remove waste products from the tissues and cooperate with the immune system in destroying invading pathogens. ■ Return filtered lymph to the veins at the base of the neck. ○ Absorption of Fats and Fat-Soluble Vitamins ■ Lacteals = specialized structures of the lymphatic system that absorb those fats that cannot be transported by the bloodstream. ○ Interstitial Fluid and Lymph Creation ■ Interstitial Fluid = plasma from arterial blood that flows out of the arterioles and into the capillaries, and then flows into the spaces between the cells of the tissues. ■ Lymph (limf) = clear, watery fluid containing electrolytes and proteins. ● Structures Of The Lymphatic System ○ Lymphatic Capillaries = microscopic, blind-ended (sealed on one end) tubes located near the surface of the body with capillary walls that are only one cell in thickness. ○ Lymphatic Vessels and Ducts ■ Lymphatic vessels = located deeper within the tissues; have valves to prevent backward flow of lymph. ● Right lymphatic duct = collects lymph from the right side of the head and neck, the upper right quadrant of the body, and the right arm; empties into the right subclavian vein. ● Thoracic duct = largest lymphatic vessel; collects lymph from the left side of the head and neck, the upper left quadrant of the trunk, the left arm, the entire lower portion of the trunk, and both legs; empties into the left subclavian vein. ■ Lymph node = small, bean-shaped; has specialized lymphocytes that are capable of destroying pathogens.

● Cervical lymph nodes → located along the sides of the neck (cervic → neck) ● Axillary lymph nodes → located under the arms (armpits) (axill → armpit) ● Inguinal lymph nodes → located in the inguinal (groin) area of the lower abdomen (inguin → groin) ○ Lymphocytes ■ Lymphocytes (lymphoid cells) = leukocytes formed in the bone marrow as stem cells; defends the body against antigens. ● Three types of lymphocytes: natural killer cells, B cells, and T cells ■ Antigen = any substance that the body regards as being foreign ■ Natural killer cells = play an important role in the killing of cancer cells and cells infected by viruses. ■ B cells (B lymphocytes) = specialized lymphocytes that produce antibodies ■ Plasma cells = develop from B cells and secrete a large volume of antibodies coded to destroy specific antigens. ■ T cells (T lymphocytes) = origin in thymus; play central role in cellmediated immunity. ■ Cytokines = group of proteins (ex: interferons and interleukins) released primarily by T cells; act as intracellular signals to begin the immune response. ■ Interferons = produced in response to the presence of antigens (ex: viruses or tumor cells); activates the immune system, fights viruses by slowing or stopping their multiplication, and signals other cells to increase their defenses. ■ Interleukins = play multiple roles in the immune system, including directing B and T cells to divide and proliferate.

● Additional Structures Of The Lymphatic System ○ The Tonsils ■ Tonsils = three masses of lymphoid tissue that form a protective ring around the back of the nose and upper throat; prevents pathogens from entering the respiratory system when breathing through the nose and mouth. ● Adenoids (nasopharyngeal tonsils) = located in the nasopharynx, which is the upper part of the pharynx. ● Palatine tonsils = located on the left and right sides of the throat in the area that is visible at the back of the mouth. ● Lingual tonsils = located at the base of the tongue; not readily visible. ○ The Thymus Gland ■ Thymus = mass of lymphoid tissue located about the heart, reaches greatest size at puberty and becomes smaller with age. ○ The Vermiform Appendix ■ Vermiform appendix (appendix) = hangs from the lower portion of the cecum (first section of the large intestine); plays role in immune system. ○ The Spleen ■ Spleen = sac-like mass of lymphoid tissue in the left upper quadrant of the abdomen; just inferior (below) the diaphragm and poster (behind) the stomach; filters microorganisms and other foreign materials from the blood; forms lymphocytes and monocytes. ● Functions And Structures Of The Immune System ○ The primary function of the immune system is to maintain good health and to protect the body from harmful substances such as: pathogens, allergens, toxins, and malignant cells. ○ The Immune System’s First Line of Defense ■ Intact skin = wraps the body in a physical barrier to prevent invading organisms from entering the body. ■ Respiratory system = traps breathed-in foreign matter with nose hairs and the moist mucous membrane lining of the respiratory system; tonsils form a protective ring around the entrance to the throat; if foreign matter

gets past these barriers, coughing and sneezing help expel it from the respiratory system. ■ Digestive system = uses acids and enzymes produced by the stomach to destroy invaders that are swallowed or consumed with food. ■ Lymphatic system = attack and destroy pathogens that have succeeded in entering the body. ○ The Antigen-Antibody Reaction ■ Antigen-antibody reaction (immune reaction) = involves binding antigens to antibodies; labels a potentially dangerous antigen so it can be recognized and destroyed by other cells of the immune system; the immune system immediately responds to the presence of any antigen ● Tolerance = an acquired unresponsiveness to a specific antigen. ● Antibody = disease-fighting protein created by the immune system in response to the presence of a specific antigen (anti → against) ○ Immunoglobulins ■ Immunoglobulins = bind with specific antigens in the antigen-antibody response; the five primary types of immunoglobulins, which are secreted by plasma cells, are also known as antibodies. ■ Phagocytes = specialized leukocytes that act as part of the antigenantibody reaction by destroying substances such as cell debris, dust, pollen, and pathogens by the process of phagocytosis. ● Phagocytosis = process of destroying pathogens by surrounding and swallowing them. ● Monocytes = leukocytes that provide immunological defenses against many infectious organisms; replenish macrophages and dendritic cells. ● Macrophage = type of leukocyte that surrounds and kills invading cells; also removes dead cells and stimulates the action of other immune cells (macro → large; -phage → a cell that eats) ● Dendritic cells = specialized leukocytes that patrol the body searching for antigens that produce infections; when such a cell is

found, dendritic cells grab it, swallow it, and alert B and T cells to act against this specific antigen. ■ Complement system = group of proteins that normally circulate in the blood in an inactive form; when needed, these cells complement the ability of antibodies to ward off pathogens by combining with them to dissolve and remove pathogenic bacteria and other foreign cells. ■ Immunity = state of being resistant to a specific disease ● Natural immunity (passive immunity) = resistance to a disease present without the administration of an antigen or exposure to a disease; present at birth and can be augmented when breast milk passes from mother to baby. ● Acquired immunity = obtained by having had a contagious disease. ● Medical Specialties Related To The Lymphatic And Immune Systems ○ Allergist = diagnoses and treats conditions of altered immunologic reactivity, such as allergic reactions. ○ Immunologist = diagnoses and treats disorders of the immune system (immun → protected) ○ Lymphologist = diagnoses and treats disorders of the lymphatic system. ○ Oncologist = diagnoses and treats malignant disorders such as tumors and cancer (onc → tumor) ● Pathology And Diagnostic Procedures Of The Lymphatic System ○ Lymphadenitis (swollen glands) = inflammation of lymph nodes (lymphaden → lymph node) ○ Lymphadenopathy = any disease process affecting a lymph node or nodes. ○ Lymphangioma = benign tumor formed by an abnormal collection of lymphatic vessels due to a congenital malformation of the lymphatic system (angi → lymph vessel)

○ Ruptured spleen = medical emergency that occurs when the covering of the spleen is torn, usually as a result of a blow to the abdomen. ○ Splenorrhagia = bleeding from the spleen (splen/o → spleen; rrhagia → bleeding) ○ Splenomegaly = abnormal enlargement of the spleen ○ Lymphoscintigraphy = diagnostic test that is performed to detect damage or malformations of the lymphatic vessels. ○ Lymphedema = swelling of the tissues due to an abnormal accumulation of lymph fluid within the tissues (-edema → swelling) ■ Primary lymphedema → hereditary condition that develops with swelling beginning in the feet and progressing into the ankles and in an upward direction along the legs; occurs most frequently in females when the symptoms begin to appear during puberty. ■ Secondary lymphedema → caused by damage to lymphatic vessels that is most frequently due to cancer treatment, surgery, trauma, or burns. ■ Bioimpedance spectroscopy = noninvasive method of diagnosing lymphedema; measures the resistance to an electrical current passed through the affected limb, with abnormally low results showing a buildup of lymph. ● Pathology And Diagnostic Procedures Of The Immune System ○ Allergic Reactions ■ Allergic reaction = occurs when the body’s immune system reacts to a harmless allergen such as pollen or food. ■ Allergy (hypersensitivity) = overreaction by the body to a particular antigen. ■ Allergen = a substance that produces an allergic reaction in an individual. ■ Localized allergen response (cellular response) = redness, itching, and burning where the skin has come into contact with an allergen.

■ Systemic reaction (anaphylaxis or anaphylactic shock) = severe response to an allergen; without prompt medical aid, patient can die within a few minutes. ■ Antihistamines = medications administered to relieve or prevent the symptoms of hayfever and other types of allergies. ○ Autoimmune Disorders ■ Autoimmune disorder (autoimmune disease) = any of a large group of diseases where the immune system produces antibodies against its own tissues, mistaking healthy cells, tissues, or organs for antigens. ○ Immunodeficiency Disorders ■ Immunodeficiency disorder = occurs when the immune response is compromised (compromised → weakened or not functioning properly) ● Severe combined immunodeficiency (SCID) = inherited condition in which abnormalities in the immune system cause an increased susceptibility to infection and failure to thrive as a result of infections. ■ Human immunodeficiency virus (HIV) = blood-borne infection where the virus damages or kills the T cells of the immune system, causing it to progressively fail, leaving the body at risk of developing life-threatening infections. ● Opportunistic infection = caused by a pathogen that does not normally produce an illness in healthy humans. ● Acquired immunodeficiency syndrome (AIDS) = most advanced and fatal stage of an HIV infection. ● Kaposi’s sarcoma = opportunistic infection associated with HIV; this cancer causes patches of abnormal tissue to grow under the skin, lining of the mouth, nose, or throat, or in other organs. ● ELISA (enzyme-linked immunosorbent assay) = blood test used to screen for the presence of HIV antibodies, as well as Lyme disease and other infectious diseases. ● Western blot test = blood test that produces more accurate results than ELISA; performed to confirm the diagnosis when the results

of ELISA are positive for HIV. ● Treatment Of The Immune System ○ Immunotherapy ■ Immunotherapy = disease treatment that involves either stimulating or repressing the immune response. ○ Antibody Therapy ■ Synthetic immunoglobulins (immune serum) = used as a post-exposure preventative measure against certain viruses, including rabies and some types of hepatitis. ■ Synthetic interferon = used in the treatment of multiple sclerosis, hepatitis C, and some cancers. ■ Monoclonal antibodies = any of a class of antibodies produced in the lab by identical offspring of a clone of specific cells; used to enhance the patient’s immune response to certain malignancies. ○ Immunosuppression ■ Immunosuppression = treatment to repress or interfere with the ability of the immune system to respond to stimulation by antigens. ● Immunosuppressant = substance that prevents or reduces the body’s normal immune response. ● Corticosteroid drug = hormone-like preparation administered primarily as an anti-inflammatory and immunosuppressant. ● Cytotoxic drug = medication that kills or damages cells (tox → poison) ● Pathogenic Organisms ○ Pathogen = microorganism that causes a disease in humans ○ Bacteria ■ Bacteria = one-celled microscopic organisms; most are not harmful ● Bacilli = rod-shaped, spore-forming bacteria ● Anthrax = contagious disease that can be transmitted through livestock infected by Bacillus anthracis.

● Rickettsia = small bacterium that lives in lice, fleas, ticks, and mites. ● Spirochetes = long, slender, spiral-shaped bacteria that have flexible walls and are capable of movement. ● Lyme disease (LIME) = transmitted by a tick that has had contact with a deer infected with Borrelia burgdorferi; symptoms include fever, headache, fatigue, skin rash (erythema migrans); can spread to the joints, heart, and nervous system. ● Staphylococci = group of about thirty species of bacteria that form irregular groups or clusters resembling grapes (staphyl/o → clusters or bunches of grapes; -cocci → spherical bacteria) ● Staphylococcus aureus (staph aureus) = form of staphylococcus that often infect wounds and cause serious problems such as toxic shock syndrome or food poisoning. ● Streptococci = bacteria that form a chain (strept/o → twisted chain) ○ Antibiotic-Resistant Bacteria ■ Antibiotic-resistant bacteria = occur when antibiotics fail to kill all of the bacteria they target; then, the surviving bacteria become resistant to this particular drug. ■ Methicillin-resistant Staphylococcus aureus (MRSA) = one of several types of bacteria that are now resistant to most antibiotics. ○ Fungus and Yeast Infections ■ Fungus = simple parasitic organism ■ Tinea pedis (athlete’s foot) = fungal infection that develops between the toes. ■ Yeast = type of fungus ■ Candidiasis (yeast infection) = occur on the skin or mucous membranes in warm, moist areas such as the vagina or mouth and are caused by the

pathogenic yeast Candida albicans. ○ Parasites ■ Parasite = plant or animal that lives on or within another living organism at the expense of that organism. ● Malaria = caused by a parasite that lives in certain mosquitoes and is transferred to humans by the bite of an infected mosquito; symptoms include fever, shaking, chills, headache, muscle aches, and fatigue. ● Toxoplasmosis = parasite that is most commonly transmitted from pets to humans by contact with contaminated animal feces. ○ Viral Infections ■ Viruses = very small infectious agents that live only by invading other cells. ● Ebola = rare and generally fatal disease transmitted by contact with any bodily fluids infected with the Ebola virus; early symptoms are high fever, vomiting, and diarrhea; late symptoms are massive internal bleeding and organ failure. ● Influenza (flu) = highly contagious viral respiratory infection that occurs in seasonal epidemics; symptoms are fever, sore throat, muscle aches, cough, runny nose, and fatigue. ● Measles = acute, highly contagious infection transmitted by respiratory droplets of the rubeola virus; symptoms: red, itchy rash over the entire body, high fever, runny nose, and coughing. ● Mumps = acute viral infection characterized by swelling of the parotid glands, which are salivary glands located just in front of the ears; in adults, it can cause swelling of the ovaries or testes. ● Rubella (German measles or three-day measles) = viral infection characterized by a low-grade fever, swollen glands, inflamed eyes, and a fine, pink rash. ● Measles, mumps, and rubella vaccination = immunization that can prevent these three viral illnesses and should be administered in early childhood.

● Rabies = acute viral infection that is transmitted to humans through the bite or saliva of an infected animal. ● West Nile virus = spread to humans by the bite of an infected mosquito. ○ Herpesviruses ■ Cytomegalovirus = found in most body fluids; “silent infection” in which a person has no signs of infection, although it can cause a serious illness when a person has a weakened immune system. ■ Varicella (chickenpox) = caused by the herpes virus Varicella zoster and is highly contagious; symptoms: fever and rash consisting of hundreds of itchy, fluid-filled blisters that burst and form crusts. ■ Herpes zoster (shingles) = acute viral infection characterized by painful skin eruptions that follow the underlying route of an inflamed nerve; occurs when dormant varicella virus is reactivated later in life. ■ Infectious mononucleosis (mono) = caused by the Epstein-Barr virus; symptoms: fever, sore throat, and enlarged lymph nodes. ○ Medications to Control Infections ■ Antibiotics = medication capable of inhibiting growth or killing pathogenic bacterial microorganisms; effective against most bacterial infections, but not viral infections. ■ Bactericide = substance that causes the death of bacteria (-cide → causing death); includes penicillins and cephalosporins. ■ Antifungal = agent that destroys or inhibits the growth of fungi (ex: lotrimin) ■ Antiviral drug = used to treat viral infections or to provide temporary immunity (ex: acyclovir) ● Oncology ○ Oncology = study of the prevention, causes, and treatment of tumors and cancer. ○ Tumors

■ Tumor (neoplasm) = abnormal growth of body tissue ● Benign = not life-threatening, although it can cause damage as it grows and can place pressure on adjacent structures. ● Myoma = example of a benign tumor made up of muscle tissue ● Malignant = becoming progressively worse and life-threatening ● Myosarcoma = example of a malignant tumor derived from muscle tissue (sarc → flesh) ● Angiogenesis = process in which a tumor supports its growth by creating its own blood supply (-genesis → reproduction) ● Antiangiogenesis = form of treatment that disrupts the blood supply to the tumor. ○ Cancer ■ Cancer = class of diseases characterized by the uncontrolled division of cells and the ability of these cells to invade other tissues. ● Metastasize = to spread from one place to another ● Metastasis = process by which cancer is spread to a new site ○ Carcinomas ■ Carcinoma = malignant tumor that occurs in epithelial tissue ● Carcinoma in situ = malignant tumor in its original position that has not yet disturbed or invaded the surrounding tissues. ● Adenocarcinoma = any one of a large group of carcinomas derived from glandular tissue. ○ Sarcomas ■ Sarcoma = malignant tumor that arises from connective tissues, including hard, soft, and liquid connective tissues. ● Hard-tissue sarcomas → arise from bone or cartilage ○ Osteosarcoma = hard-tissue sarcoma that usually involves the upper shaft of the large bones, pelvis, or knee. ● Soft-tissue sarcomas → cancers of the muscle, fat, fibrous tissue,

blood and lymphatic vessels, or other supporting tissue, including the synovial tissues that line the cavities of joints. ○ Synovial sarcoma = tumor of the tissues surrounding a synovial joint such as the knees or elbows. ● Liquid-tissue sarcomas → arise from blood and lymph ○ Leukemia = cancer of the white blood-forming cells in the bone marrow. ○ Staging Tumors ■ Staging = process of classifying tumors by how far the disease has progressed, the potential for its responding to therapy, and the patient’s prognosis. ○ Lymphomas ■ Lymphoma = general term applied to malignancies affecting lymphoid tissues. ● Hodgkin’s lymphoma (Hodgkin’s disease) = cancer of the immune system distinguished by the presence of large, cancerous lymphocytes known as Reed-Sternberg cells. ● Non-Hodgkin’s lymphoma = more common type, refers to all lymphomas other than Hodgkin’s lymphoma. ○ Breast Cancer ■ Breast cancer = carcinoma that develops from the cells of the breasts and can spread to adjacent lymph nodes and other body sites; most grow in response to estrogen ...