Essentials of Human Anatomy Physiology Elaine N Marieb

Lymph Nodes Figure 12. 3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin

The Lymphatic System · Two parts · Lymphatic vessels · Lymphoid tissues and organs · Lymphatic system functions · Transport fluids back to the blood · Play essential roles in body defense and resistance to disease · Absorb digested fat at the intestinal villi Slide 12. 1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Lymphatic Characteristics · Lymph – excess tissue fluid carried by lymphatic vessels · Properties of lymphatic vessels · One way system toward the heart · No pump · Lymph moves toward the heart · Milking action of skeletal muscle · Rhythmic contraction of smooth muscle in vessel walls Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 12. 2

Lymphatic Vessels Figure 12. 1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin

Lymphatic Vessels · Lymphatic collecting vessels · Collects lymph from lymph capillaries · Carries lymph to and away from lymph nodes Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 12. 2 Slide

Lymphatic Vessels · Lymphatic collecting vessels (continued) · Returns fluid to circulatory veins near the heart · Right lymphatic duct · Thoracic duct Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 12. 2 Slide

Lymph · Materials returned to the blood · Water · Blood cells · Proteins

Lymph · Harmful materials that enter lymph vessels · Bacteria · Viruses · Cancer

Lymph Nodes · Filter lymph before it is returned to the blood · Defense cells within lymph nodes · Macrophages – engulf and destroy foreign substances · Lymphocytes – provide immune response to antigens Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Lymph Node Structure Figure 12. 4 Copyright © 2003 Pearson Education, Inc. publishing as

Other Lymphoid Organs · Several other organs contribute to lymphatic function · Spleen · Thymus · Tonsils · Peyer’s patches Figure 12. 5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 12. 9

The Spleen · Located on the left side of the abdomen · Filters blood · Destroys worn out blood cells · Forms blood cells in the fetus · Acts as a blood reservoir Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

The Thymus · Located low in the throat, overlying the heart · Functions at peak levels only during childhood · Produces hormones (like thymosin) to program lymphocytes Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Tonsils · Small masses of lymphoid tissue around the pharynx · Trap and remove bacteria and other foreign materials · Tonsillitis is caused by congestion with bacteria Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Peyer’s Patches · Found in the wall of the small intestine · Resemble tonsils in structure · Capture and destroy bacteria in the intestine Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Mucosa-Associated Lymphatic Tissue (MALT) · Includes: · Peyer’s patches · Tonsils · Other small accumulations of lymphoid tissue · Acts as a guard to protect respiratory and digestive tracts Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Body Defenses · The body is constantly in contact with bacteria, fungi, and viruses (pathogens) · The body has two defense systems foreign materials · Nonspecific defense system · Mechanisms protect against a variety of invaders · Responds immediately to protect body from foreign materials Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Body Defenses · Specific defense system · Specific defense is required for each type of invader · Also known as the immune system Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Nonspecific Body Defenses · Body surface coverings · Intact skin · Mucous membranes · Specialized human cells · Chemicals produced by the body Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Surface Membrane Barriers – First Line of Defense · The skin · Physical barrier to foreign materials · p. H of the skin is acidic to inhibit bacterial growth · Sebum is toxic to bacteria · Vaginal secretions are very acidic Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Surface Membrane Barriers – First Line of Defense · Stomach mucosa · Secretes hydrochloric acid · Has protein-digesting enzymes · Saliva and lacrimal fluid contain lysozyme · Mucus traps microogranisms in digestive and respiratory pathways Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Defensive Cells · Phagocytes (neutrophils and macrophages) · Engulfs foreign material into a vacuole · Enzymes from lysosomes digest the material Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 12. 6 b Slide

Macrophage attacking e-coli. •

Defensive Cells · Natural killer cells · Can lyse and kill cancer cells · Can destroy virus- infected cells Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 12. 6 b Slide

Inflammatory Response - Second Line of Defense · Triggered when body tissues are injured · Produces four cardinal signs · Redness · Heat · Swelling · Pain · Results in a chain of events leading to protection and healing Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Functions of the Inflammatory Response · Prevents spread of damaging agents · Disposes of cell debris and pathogens · Sets the stage for repair Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Steps in the Inflammatory Response Figure 12. 7 Copyright © 2003 Pearson Education, Inc.

Antimicrobial Chemicals · Complement · A group of at least 20 plasma proteins · Activated when they encounter and attach to cells (complement fixation) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 12. 8 Slide

Antimicrobial Chemicals · Complement (continued) · Damage foreign cell surfaces · Will rupture or lyse the foreign cell membrane Figure 12. 8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Antimicrobial Chemicals · Interferon · Secreted proteins of virus-infected cells · Bind to healthy cell surfaces to inhibit viruses binding Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Interferons are a family species-specific proteins synthesized by eukaryotic cells in response to viruses and a variety of natural and synthetic stimuli. There are several different interferons commonly used as therapeutics, termed alpha, beta, and gamma. These peptides are used to treat hairy cell leukemia, AIDS-related Kaposi's sarcoma, laryngeal papillomatosis, genital warts, and chronic granulomatous disease. Side effects include black tarry stools, blood in the urine, confusion, and loss of balance.

Fever · Abnormally high body temperature · Hypothalmus heat regulation can be reset by pyrogens (secreted by white blood cells) · High temperatures inhibit the release of iron and zinc from liver and spleen needed by bacteria · Fever also increases the speed of tissue repair Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Specific Defense: The Immune System – Third Line of Defense · Antigen specific – recognizes and acts against particular foreign substances · Systemic – not restricted to the initial infection site · Has memory – recognizes and mounts a stronger attack on previously encountered pathogens Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Types of Immunity · Humoral immunity · Antibody-mediated immunity · Cells produce chemicals for defense · Cellular immunity · Cell-mediated immunity · Cells target virus infected cells Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Antigens (Nonself) · Any substance capable of exciting the immune system and provoking an immune response · Examples of common antigens · Foreign proteins · Nucleic acids · Large carbohydrates · Some lipids · Pollen grains · Microorganisms Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Self-Antigens · Human cells have many surface proteins · Our immune cells do not attack our own proteins · Our cells in another person’s body can trigger an immune response because they are foreign · Restricts donors for transplants Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Allergies · Many small molecules (called haptens or incomplete antigens) are not antigenic, but link up with our own proteins · The immune system may recognize and respond to a protein-hapten combination · The immune response is harmful rather than protective because it attacks our own cells Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Cells of the Immune System · Lymphocytes · Originate from hemocytoblasts in the red bone marrow · B lymphocytes become immunocompetent in the bone marrow · T lymphocytes become immunocompetent in the thymus · Macrophages · Arise from monocytes · Become widely distributed in lymphoid organs Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Activation of Lymphocytes Figure 12. 9 Copyright © 2003 Pearson Education, Inc. publishing as

Humoral (Antibody-Mediated) Immune Response · B lymphocytes with specific receptors bind to a specific antigen · The binding event activates the lymphocyte to undergo clonal selection · A large number of clones are produced (primary humoral response) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Humoral (Antibody Mediated) Immune Response · Most B cells become plasma cells · Produce antibodies to destroy antigens · Activity lasts for four or five days · Some B cells become long-lived memory cells (secondary humoral response) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Humoral Immune Response Figure 12. 10 Copyright © 2003 Pearson Education, Inc. publishing as

Active Immunity · Your B cells encounter antigens and produce antibodies · Active immunity can be naturally or artificially acquired Figure 12. 12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Passive Immunity · Antibodies are obtained from someone else · Conferred naturally from a mother to her fetus · Conferred artificially from immune serum or gamma globulin · Immunological memory does not occur · Protection provided by “borrowed antibodies” Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Antibodies (Immunoglobulins) (Igs) · Soluble proteins secreted by B cells (plasma cells) · Carried in blood plasma · Capable of binding specifically to an antigen Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Antibody Classes · Antibodies of each class have slightly different roles · Five major immunoglobulin classes – (Do Not Need to know!) · Ig. M – can fix complement · Ig. A – found mainly in mucus · Ig. D – important in activation of B cell · Ig. G – can cross the placental barrier · Ig. E – involved in allergies Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Cellular (Cell-Mediated) Immune Response · Antigens must be presented by macrophages to an immunocompetent T cell (antigen presentation) · T cells must recognize nonself and self (double recognition) · After antigen binding, clones form as with B cells, but different classes of cells are produced Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Cellular (Cell-Mediated) Immune Response Figure 12. 15 Copyright © 2003 Pearson Education, Inc. publishing

T Cell Clones · Cytotoxic T cells · Specialize in killing infected cells · Insert a toxic chemical (perforin) · Helper T cells · Recruit other cells to fight the invaders · Interact directly with B cells Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

T Cell Clones · Suppressor T cells · Release chemicals to suppress the activity of T and B cells · Stop the immune response to prevent uncontrolled activity · A few members of each clone are memory cells Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Summary of the Immune Response Figure 12. 16 Copyright © 2003 Pearson Education, Inc.

Organ Transplants and Rejection · Major types of grafts · Autografts – tissue transplanted from one site to another on the same person · Isografts – tissue grafts from an identical person (identical twin) · Allografts – tissue taken from an unrelated person · Xenografts – tissue taken from a different animal species Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Organ Transplants and Rejection · Autografts and isografts are ideal donors · Xenografts are never successful · Allografts are more successful with a closer tissue match Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Disorders of Immunity: Immunodeficiencies · Production or function of immune cells or complement is abnormal · May be congenital or acquired · Includes AIDS – Acquired Immune Deficiency Syndrome Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Disorders of Immunity: Autoimmune Diseases · The immune system does not distinguish between self and nonself · The body produces antibodies and sensitized T lymphocytes that attack its own tissues Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Disorders of Immunity: Autoimmune Diseases · Examples of autoimmune diseases · Multiple sclerosis – white matter of brain and spinal cord are destroyed · Myasthenia gravis – impairs communication between nerves and skeletal muscles · Juvenile diabetes – destroys pancreatic beta cells that produce insulin · Rheumatoid arthritis – destroys joints Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Disorders of Immunity: Autoimmune Diseases · Examples of autoimmune diseases (continued) · Systemic lupus erythematosus (SLE) – affects kidney, heart, lung and skin · Glomerulonephritis – impairment of renal function Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

Immune Deficiency: AIDS • HIV targets cells • Retrovirus attaches to CD 4 receptors of T helper cells – Transmission: Body fluids, i. e. , blood, semen, breast milk, vaginal secretions

The Structure of HIV Figure 9. 19

Time Course of the Progression of AIDS after HIV Infection Figure 9. 21

• AIDS progression: –Phase I: few weeks to a few years; flu like symptoms, swollen lymph nodes, chills, fever, fatigue, body aches. Virus is multiplying, antibodies are made but ineffective for complete virus removal –Phase II: within six months to 10 years; opportunistic infections present, Helper T cells affected, 5% may not progress to next phase –Phase III: Helper T cells fall below 200 per cubic millimeter of blood AND the person has an opportunistic infection or type of cancer. Person is now termed as having “AIDS” May include pneumonia, meningitis, tuberculosis, encephalitis, Kaposi’s sarcoma, and non-Hodgkin’s lumphoma….

AIDS Pandemic • More than 36 million infected with HIV worldwide • Most infections in sub-Sahara of Africa • Increasing spread in Asia and India • Most often spread by heterosexual contact outside U. S.