The Lymphatic & Immune Systems Chapter 17

Lymphatic System Page 298 Supplements the circulatory system Composed of lymph, lymph nodes, lymph vessels, the spleen, the thymus gland, lacteals (lymphoid tissue in the intestinal tract), & the tonsils Unlike the circulatory system there is no muscular pump or heart Peyer’s patches

Functions of the Lymphatic System Page 299 Functions of the Lymphatic System Acts as intermediary between blood & tissue Transports excess filtered tissue fluid Produces lymphocytes to destroy harmful bacteria Lacteals absorb fat & fat soluble vitamins. Spleen produces lymphocytes & monocytes Thymus gland produces T lymphocytes

Interstitial Fluid (intercellular) Page 299 Interstitial Fluid (intercellular) Straw colored; No red blood cells or proteins (similar in composition to blood plasma) Called lymph when fluid enters lymph capillaries Moves with assistance of skeletal tissue contraction, breathing movements, & valves Some of the fluid may not get reabsorbed, which results in swelling of the tissue & the resulting condition is known as edema. Composed of water, lymphocytes, some granulocytes, digested nutrients, hormones, salts, carbon dioxide, & urea.

Lymph Vessels Page 299 Lymph vessels = Closely parallel the veins Lymph capillaries begin as blind-ended tubes. Smaller vessels unite to form larger vessels & these in turn, join forming larger & larger lymph vessels called lymphatics. The two main lymphatic vessels are: Right lymphatic duct receives from the right side of the arm, right side of the head, & upper limbs. Drains into the right subclavian vein. Left lymphatic duct (thoracic duct) receives from the left side of the chest, head, neck, abdominal area, & lower limbs. Drains into the left subclavian vein. Flows in only one direction from organs to the heart (not a circuit) Both subclavian veins pour into the superior vena cava

Page 300 Lymph Nodes Small structures located alone or grouped in various places along the lymph vessels throughout the body Trabeculae – capsules of fibrous connective tissue that extends into the node; they divide the node into a series of compartments that contain lymphatic sinuses & lymphatic tissue. Afferent lymphatic vessels When germinal centers are stimulated, the immune response is activated Swelling in the lymph glands is known as lymphadenitis

Pages 300 – 301 Tonsils Masses of lymphatic tissue that produce lymphocytes & filter out bacteria Three pairs of tonsils Palatine – located on the sides of the soft palate Adenoids – upper part of the throat Lingual – found at the back of the tongue Tonsillitis – when tonsils become infected & enlarged, this can cause difficulty in swallowing, severe sore throat, elevated temperature, & chills

Pharyngeal is also known as the adenoids

Page 301 Spleen Saclike mass of lymphatic tissue; Forms lymphocytes & monocytes; Filters out bacteria; & Stores red blood cells Located: upper left of the abdomen beneath the diaphragm During excessive bleeding or vigorous exercise, the spleen, contracts, forcing the stored RBCs into circulation. It also destroys & removes old or fragile RBCs, & forms erythrocytes in the embryo.

Pharyngeal is also known as the adenoids

Page 302 Thymus Gland Located: in the upper anterior part of the thorax, above the heart Produces & matures lymphocytes (T lymphocytes) It is also an endocrine gland that secretes a hormone called thymosin

Pharyngeal is also known as the adenoids

Peyer’s Patches Page 302 Located: in the walls of the small intestines Produce macrophages Macrophages destroy bacteria & prevent bacteria from penetrating the walls of the small intestines

Lacteals Page 302 Specialized lymph capillaries Found in villi of the small intestine Absorb digested fat & fat-soluble vitamins

Effects of Aging Page 303 SB Decline in immune function Increased risk of infection Decreased ability to fight disease Slowed wound healing

Disorders of the Lymph System Page 302 Disorders of the Lymph System Lymphadema – swelling of the tissues due to an abnormal collection of lymph. It is caused by damage to the lymph system that prevents lymph from draining properly. Lymphoma – a tumor of the lymphatic tissue, usually malignant. Hodgkin’s disease – distinguished from other lymphomas by the presence of large cancerous lymphocytes known as Reed-Strenberg cells. Infectious mononucleosis – disease caused by the Epstein-Barr virus.

Function of Immune System Page 303 Function of Immune System Protect body from harmful substances such as: Pathogens (disease producing agents) Allergens Toxins Malignant cells

Page 303 Immunity Immunity = The body’s ability to resist infections from pathogens, foreign substances, & toxic chemicals Individuals differ in their ability to resist infection & an individuals resistance varies at different times. Humoral immunity: B cells & antibodies Cellular immunity: T cells

Normal Defense Mechanisms Page 303 Normal Defense Mechanisms The individual’s immune system serves as the normal defense mechanism against the transmission of infectious agents Ability to recognize foreign agent (antigen) Antibodies protect body against antigens Specific & nonspecific immune defenses

Antigen-Antibody Reaction Page 303 Antigen-Antibody Reaction Also known as immune reaction & involves binding antigens to antibodies An antigen is identified as any substance that the bod regards as being foreign Antibody is a disease-fighting protein

Nonspecific Immune Defense Page 303 Nonspecific Immune Defense Protects from all microorganisms & is not dependent on prior antigen exposure these include: Skin & normal flora serve as a physical barrier against infectious agents Mucous membranes entrap infectious agents & contain antibodies, lactoferrin, & lysozyme, which inhibit bacteria growth. Sneezing, coughing, & tearing reflexes physically expel mucus & microorganisms with force.

Nonspecific Immune Defense (Cont’d) Page 304 Nonspecific Immune Defense (Cont’d) Elimination & acidic environment prevent microbial growth of pathogenic organism. Inflammation is the nonspecific response to cellular injury. Immunoglobulins: IgG, IgM, IgD, IgE, IgA – a class of specialized proteins that function as antibodies.

Specific Immune Defense Page 304 Specific Immune Defense Lymphocytes are precursors of many cells involved in immune response B cells – lymphocytes found in the lymph node, spleen, & other lymphoid tissue when they replicate. Plasma cells – formed by B cells & produce huge quantities of the same antibody or immunoglobulin. Helper T cells – stimulates the production of killer T cells & more B cells to fight the invading pathogens.

Specific Immune Defense (Cont’d) Page 304 Specific Immune Defense (Cont’d) Killer T cells – kill virus-invaded body cells & cancerous body cells Suppressor T cells – slow down the activities of B & T cells once an infection has been controlled. Memory cells – descendants of activated T & B cells produced during an initial immune response Macrophages – engulf & digest the antigens.

Chemical & Immune Response Page 304 Chemical & Immune Response Lymphokines & interleukins are released by lymphocytes & macrophages as a part of the immune response Activated macrophages release cytokines Interferon is produced by cells that have been infected by a virus; binds to surroundings helping to protect them from the virus TNF kills tumor cells; attracts macrophages Complements cascade cause breakdown (lysis) of microorganisms & enhances inflammatory process Lymphokine are released by the sensitized lymphocytes on contact with specific antigens that help cellular immunity by stimulating activities of monocytes & macorphages

Natural & Acquired Immunities Pages 305 – 307 Natural & Acquired Immunities Natural immunity = Immunity we are born with, it is inherited & permanent Acquired Natural – reaction that occurs as a result of exposure to invaders e.g., measles as a child Artificial – inculcation with a vaccine, antigen or toxoid e.g., tetanus injection Passive acquired immunity = Acquired artificially by injecting antibodies, temporary protection, lasts only 3–5 weeks

Page 307 Immunization Process of increasing an individual’s resistance to an infection by artificial means Immunization charts Ages 0–6 Ages 7–18 Adult Catch-up The charts are on pages 308-312

Page 307 & 313 Autoimmunity Autoimmune disorder = when the body mistakenly targets the normal cells, tissues, & organs of a person’s own body Can be triggered by multiple causes Causes can be genetic familial predisposition, viral, or even sunlight (which can act as a trigger for lupus)

Autoimmune Disorders Page ? Addison’s disease Hypothyroidism/hyperthyroidism Lupus/systemic lupus erythematosus Multiple sclerosis Myasthenia gravis Pernicious anemia Psoriasis Rheumatoid arthritis Scleroderma Type I diabetes mellitus Ulcerative colitis/Crohn’s disease

Hypersensitivity Pages 313 – 314 Hypersensitivity = occurs when the body’s immune system fails to protect itself against foreign material Allergens = an antigen that causes allergic response Anaphylaxis (anaphylactic shock) = an even more severe & sometimes fatal allergic reaction People with such hypersensitivity should wear Medic-alert tags to alert medical professionals in the event of an emergency. Anaphylaxis = breathing problems, headache, facial swelling, falling BP, stomach cramps, & vomiting. If proper care is not administered immediately death my occur in minutes.

Page 314 HIV/AIDS Human immunodeficiency virus (HIV) causes AIDS; it destroys the body’s T4 lymphocytes which allows for Opportunistic infections Three outcomes from infection with HIV Asymptomatic infection AIDS-related complex (ARC) AIDS A – Acquired = The disease is not inherited I – Immune = Refers to the body’s natural defenses against cancers, disease, and infections D – Deficiency = Lacks cellular immunity S – Syndrome = Involves the set of diseases or conditions that are present to signal the diagnosis

HIV/AIDS Statistics Pages 314 – 315 50,000 people in the US infected annually 2.1 million people in the US living with AIDS

Transmission of HIV/AIDS Page 315 Transmission of HIV/AIDS Sexual contact Sharing hypodermic needles From infected mother to baby (in utero) at birth, through breast feeding Transfusion of contaminated blood, semen donations, skin grafts/organ transplants from & infected person Scientists have found no evidence that HIV is spread through sweat, tears, urine, or feces. The virus is fragile & doesn’t live outside the body long

Screening Tests for HIV/AIDS Page 315 Screening Tests for HIV/AIDS ELISA Western blot assay Rapid test Home sampling – FDA approved test kit

Symptoms of HIV/AIDS Pages 315 – 316 Flu-like symptoms (lack of energy, cough, frequent fevers), weight loss, night sweats, shortness of breath, some mental impairment Blotchy red rash on the upper torso Enlarged lymph glands Opportunistic conditions Bacterial infections Cancers Parasitic infections Fungal infections Viral infections Bacterial infections such as tuberculosis, which is the most common infection Cancers espcially Kaposi’s sarcoma, cervical cancer, or lymphomas

Treatment of HIV/AIDS Pages 316 – 317 No cure for AIDS Drugs used in combination to control the virus Combinations of drugs extend life of infected individuals

Preventing Transmission of HIV/AIDS Page 317 Preventing Transmission of HIV/AIDS Education & training Limit sexual contacts Use of condoms Do not share needles Clean up soiled materials Cover wounds Tell partner if you have HIV/AIDS Standard precautions used by all health care professionals