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30 Lecture Ppt


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30 Lecture Ppt

  1. 1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 30 Lymph Transport and Immunity
  2. 2. The Lymphatic System Functions in Transport and Immunity
  3. 3. 30.1 Lymphatic vessels transport lymph <ul><li>Lymphatic system is closely associated with the cardiovascular system </li></ul><ul><li>Has four main functions that contribute to homeostasis </li></ul><ul><ul><li>Lymphatic capillaries absorb excess tissue fluid and return it to the bloodstream </li></ul></ul><ul><ul><li>In the small intestines, lymphatic capillaries called lacteals absorb fats in the form of lipoproteins and transport them to the bloodstream </li></ul></ul><ul><ul><li>The lymphatic system is responsible for the production, maintenance, and distribution of lymphocytes </li></ul></ul><ul><ul><li>The lymphatic system helps defend the body against pathogens </li></ul></ul><ul><li>Lymphatic vessels form a one-way system that begins with lymphatic capillaries </li></ul><ul><ul><li>Lymphatic capillaries take up excess tissue fluid, lymph </li></ul></ul><ul><ul><ul><li>Lymph also contains defense molecules, antibodies , which are produced by lymphocytes </li></ul></ul></ul>
  4. 4. Figure 30.1 The vessels and organs of the lymphatic system
  5. 5. 30.2 Lymphatic organs defend the body <ul><li>Red bone marrow - site of stem cells capable of producing lymphocytes </li></ul><ul><ul><li>Become mature B cells, a major type of lymphocyte, in the bone marrow </li></ul></ul><ul><li>Thymus gland - located in thoracic cavity between trachea and sternum </li></ul><ul><ul><li>T cells, the other major type of lymphocyte, migrate from the bone marrow through the bloodstream to thymus, where they mature </li></ul></ul><ul><li>Lymph nodes - small, ovoid structures occurring along lymphatic vessels </li></ul><ul><ul><li>Located at body nodes, such as groin and armpits </li></ul></ul><ul><ul><li>Have many open spaces called sinuses </li></ul></ul><ul><li>Spleen - located in upper left side of abdominal cavity posterior to stomach </li></ul><ul><ul><li>Most of the spleen is red pulp that filters the blood </li></ul></ul><ul><ul><li>Red pulp consists of blood vessels and sinuses, where macrophages remove old and defective blood cells </li></ul></ul><ul><li>Patches of lymphatic tissue in the body: </li></ul><ul><ul><li>Tonsils , in pharynx; Peyer patches located in intestine; and appendix </li></ul></ul>
  6. 6. Figure 30.2 The lymphatic organs
  7. 7. The Body’s First Line of Defense Against Disease Is Nonspecific and Innate
  8. 8. 30.3 Barriers to entry, complement proteins, and certain blood cells are first responders <ul><li>Barriers to entry such as the skin </li></ul><ul><ul><li>Nonchemical, mechanical barriers, such as the skin and the mucous membranes </li></ul></ul><ul><ul><li>Protective proteins </li></ul></ul><ul><ul><ul><li>Complement proteins are composed of a number of blood plasma proteins that “complement” certain immune responses and help destroy pathogens in three ways </li></ul></ul></ul><ul><ul><ul><ul><li>Bind to mast cells and trigger histamine release to create enhanced inflammation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Bind to the surface of pathogens already coated with antibodies </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Form a membrane attack complex that produces holes in the surface of some bacteria and viruses </li></ul></ul></ul></ul><ul><ul><ul><li>Interferons are cytokines - soluble proteins that affect the behavior of other cells </li></ul></ul></ul><ul><li>Inflammatory response </li></ul>
  9. 9. Phagocytes and Natural Killer Cells <ul><li>Neutrophils are cells that are able to leave the bloodstream and engulf bacteria in connective tissues </li></ul><ul><li>Eosinophils are phagocytic, but they are better known for mounting an attack against animal parasites </li></ul><ul><ul><li>The two most powerful of the phagocytic white blood cells are macrophages and macrophage - derived dendritic cells </li></ul></ul><ul><li>Natural killer (NK) cells are large, granular lymphocytes that kill virus-infected cells and cancer cells by cell-to-cell contact </li></ul>
  10. 10. Figure 30.3A Overview of nonspecific defenses
  11. 11. Figure 30.3B Action of the complement system against a bacterium
  12. 12. APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 30.4 A fever can be beneficial <ul><li>Several hypotheses have been proposed as to the benefits of a fever </li></ul><ul><ul><li>Perhaps a fever is the body’s way of informing us that something is wrong </li></ul></ul><ul><ul><li>At times, a fever may directly participate in overcoming an illness </li></ul></ul><ul><ul><ul><li>Example: a fever can contribute to the host’s defense by providing an unfavorable environment for the invader </li></ul></ul></ul><ul><ul><li>A fever may stimulate immunity </li></ul></ul><ul><ul><ul><li>A fever has been shown to limit the growth of tumor cells more severely than that of normal body cells </li></ul></ul></ul>
  13. 13. 30.5 The inflammatory response is a localized response to invasion <ul><li>Inflammatory response - a series of events that occur whenever tissue is damaged </li></ul><ul><ul><li>An inflamed area has four outward signs: </li></ul></ul><ul><ul><ul><li>redness, heat, swelling, and pain </li></ul></ul></ul><ul><li>Steps in the inflammatory response </li></ul><ul><ul><li>Chemical mediators, such as histamine , cause the capillaries to dilate and become more permeable </li></ul></ul><ul><ul><li>Migration of phagocytes, namely neutrophils and monocytes, also occurs during the inflammatory response </li></ul></ul><ul><ul><li>Macrophages also release colony-stimulating factors, cytokines that pass by way of the blood to the red bone marrow, where they stimulate the production and release of white blood cells </li></ul></ul><ul><ul><li>A blood clot can form to seal a break in a blood vessel </li></ul></ul>
  14. 14. Figure 30.5A Inflammatory response
  15. 15. Figure 30.5B A macrophage engulfing bacteria
  16. 16. The Body’s Second Line of Defense Against Disease Is Specific to the Pathogen
  17. 17. 30.6 The second line of defense targets specific antigens <ul><li>Immunity is complete when a foreign substance is unable to cause an infection </li></ul><ul><ul><li>First - specific defense requires that the body be able to recognize a particular molecule, an antigen </li></ul></ul><ul><ul><ul><li>Other antigens are termed self-antigens because the body itself produces them </li></ul></ul></ul><ul><ul><li>Second - after recognizing antigens, the immune system can respond to them </li></ul></ul><ul><ul><li>Third - the immune system can remember antigens it has met before </li></ul></ul>
  18. 18. 30.7 Specific immunity can be active or passive <ul><li>Active Immunity </li></ul><ul><ul><li>Develops naturally after a person is infected with a pathogen </li></ul></ul><ul><ul><li>Vaccine contains antigens that cause body to develop antibodies specific to these antigens </li></ul></ul><ul><li>Passive Immunity </li></ul><ul><ul><li>Occurs when an individual is given prepared antibodies (immunoglobulins) to combat a disease </li></ul></ul><ul><ul><ul><li>Since these antibodies are not produced by the individual’s plasma cells, passive immunity is short-lived </li></ul></ul></ul><ul><ul><ul><li>Even though passive immunity does not last, it is sometimes used to prevent illness in a patient who has been unexpectedly exposed to an infectious disease </li></ul></ul></ul>
  19. 19. Figure 30.7A  Vaccines immunize children against diseases Figure 30.7B Breastfeeding provides infants with antibodies
  20. 20. 30.8 Lymphocytes are directly responsible for specific defenses <ul><li>Specific defenses primarily depend on two types of lymphocytes - B cells and T cells </li></ul><ul><ul><li>Capable of recognizing antigens because they have specific antigen receptors </li></ul></ul><ul><ul><ul><li>B cells have B cell receptors (BCR) </li></ul></ul></ul><ul><ul><ul><li>T cells have T cell receptors (TCR) </li></ul></ul></ul><ul><li>B cells are responsible for antibody-mediated immunity </li></ul><ul><ul><li>Once a B cell combines with an antigen, it gives rise to plasma cells , which produce specific antibodies </li></ul></ul><ul><li>T cells are responsible for cell-mediated immunity </li></ul><ul><ul><li>T cells do not recognize an antigen until it is presented to them by an antigen-presenting cell (APC) </li></ul></ul><ul><ul><li>Cells differentiate into either helper T cells , which release cytokines, or cytotoxic T cells , which attack and kill virus-infected cells </li></ul></ul>
  21. 22. Figure 30.8 Overview of specific defenses
  22. 23. 30.9 Antibody-mediated immunity involves B cells <ul><li>Clonal selection model describes what happens when a B cell receptor (BCR) combines with an antigen </li></ul><ul><ul><li>Antigen “selects” the B cell that will clone </li></ul></ul><ul><ul><ul><li>Cytokines secreted by helper T cells stimulate B cells to clone </li></ul></ul></ul><ul><ul><li>Defense by B cells is called antibody-mediated immunity because most members of a clone become plasma cells that produce specific antibodies </li></ul></ul><ul><li>Immunization involves the use of vaccines to bring about clonal expansion, not only of B cells, but also of T cells </li></ul><ul><li>Antibodies also known as immunoglobulin (Ig) </li></ul><ul><ul><li>Most typical antibody, called IgG, is a Y-shaped </li></ul></ul><ul><ul><li>molecule with two arms </li></ul></ul><ul><ul><li>IgG has constant regions, where the sequence </li></ul></ul><ul><ul><li>of amino acids is set, and variable regions, </li></ul></ul><ul><ul><li>where the sequence of amino acids varies </li></ul></ul><ul><ul><li>between IgGs </li></ul></ul>
  23. 24. Figure 30.9A Clonal selection model as it applies to B cells
  24. 25. Figure 30.9B Antibody titers
  25. 26. 30.10 Cell-mediated immunity involves several types of T cells <ul><li>T cells develop into T cell receptors (TCR) </li></ul><ul><ul><li>When a T cell leaves the thymus, it has a unique TCR, just as B cells have a BCR </li></ul></ul><ul><ul><li>T cells are unable to recognize an antigen alone </li></ul></ul><ul><ul><ul><li>Antigen must be displayed by antigen-presenting cell (APC) </li></ul></ul></ul><ul><ul><li>APC breaks the pathogen apart in a lysosome </li></ul></ul><ul><ul><ul><li>Piece of the pathogen is then displayed in an MHC (major histocompatibility complex) protein </li></ul></ul></ul><ul><li>Types of T Cells </li></ul><ul><ul><li>Cytotoxic T cells have storage vacuoles containing perforins and storage vacuoles containing enzymes called granzymes </li></ul></ul><ul><ul><li>Helper T cells play a critical role in coordinating nonspecific defenses and specific defenses, including both cell-mediated immunity and antibody-mediated immunity </li></ul></ul>
  26. 27. Figure 30.10A Clonal selection model as it applies to T cells
  27. 28. Figure 30.10B Cell-mediated immunity
  28. 29. Cytokines and Cancer Therapy <ul><li>Cytokine simply means a soluble protein that acts as a signaling molecule </li></ul><ul><ul><li>Cytokines stimulate white blood cells, they have been studied as a possible adjunct therapy for cancer </li></ul></ul><ul><li>Cytokines called interleukins are produced by white blood cells, and they act to stimulate other white blood cells </li></ul><ul><ul><li>When cancer cells carry an altered protein on their cell surface, they should be attacked and destroyed by cytotoxic T cells </li></ul></ul><ul><li>Tumor necrosis factor (TNF) is a cytokine produced by macrophages that has the ability to promote the inflammatory response and to cause the death of cancer cells </li></ul><ul><ul><li>TNF stimulates the body’s immune cells to fight cancer </li></ul></ul>
  29. 30. APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 30.11 Monoclonal antibodies have many uses <ul><li>Every plasma cell derived from a single B cell secretes antibodies against a specific antigen </li></ul><ul><ul><li>Called monoclonal antibodies because all of them are the same type </li></ul></ul><ul><li>Research Uses for Monoclonal Antibodies </li></ul><ul><ul><li>Monoclonal antibodies are useful because of their extreme specificity for a particular molecule </li></ul></ul><ul><li>Medical Uses for Monoclonal Antibodies </li></ul><ul><ul><li>Can be used to make quick and certain diagnoses of various conditions </li></ul></ul><ul><ul><ul><li>Used to signify pregnancy by detecting a particular hormone in the urine of a woman after she becomes pregnant </li></ul></ul></ul><ul><ul><ul><li>Monoclonal antibodies can be used not only to diagnose infections and illnesses but also to fight them </li></ul></ul></ul><ul><ul><ul><li>Monoclonal antibodies have shown promise as potential drugs to fight disease </li></ul></ul></ul>
  30. 31. Figure 30.11 Production of monoclonal antibodies
  31. 32. Abnormal Immune Responses Can Have Health Consequences
  32. 33. 30.12 Tissue rejection makes transplanting organs difficult <ul><li>Certain organs could be transplanted easily from one person to another if the body did not reject them </li></ul><ul><ul><li>Rejection occurs because antibodies and cytotoxic T cells bring about the destruction of foreign tissues in the body </li></ul></ul><ul><li>It is best if the transplanted organ has the same type of MHC antigens as those of the recipient </li></ul><ul><ul><li>Cytotoxic T cells recognize foreign MHC antigens </li></ul></ul><ul><ul><li>Well-known immunosuppressive drugs act by inhibiting the production of certain cytokines that stimulate cytotoxic T cells </li></ul></ul><ul><li>Xenotransplantation, the transplantation of animal tissues and organs into human beings, is another way to solve the problem of rejection </li></ul><ul><ul><li>Genetic engineering can make pig organs less antigenic by removing the MHC antigens </li></ul></ul>
  33. 34. 30.13 Autoimmune disorders are long-term illnesses <ul><li>Autoimmune disorders - failure of the immune system to distinguish between foreign antigens and the self-antigens </li></ul><ul><ul><li>Chronic inflammation occurs, and cytotoxic T cells or antibodies mistakenly attack the body’s own cells </li></ul></ul><ul><li>Rheumatoid arthritis causes recurring inflammation in synovial joints </li></ul><ul><ul><li>Complement proteins, T cells, and B cells all participate in deterioration of the joints, which eventually become immobile </li></ul></ul><ul><li>Systemic lupus erythematosus (lupus) is characterized by presence of antibodies to the nuclei of body’s cells </li></ul><ul><ul><li>Affects multiple tissues and organs, and is poorly understood </li></ul></ul><ul><li>Exact events that trigger an autoimmune disorder are not known </li></ul><ul><ul><li>Some autoimmune disorders set in following a noticeable infection </li></ul></ul><ul><ul><li>Most autoimmune disorders probably start after an undetected inflammatory response </li></ul></ul>
  34. 35. Figure 30.13A Rheumatoid arthritis <ul><li>Figure 30.13B Systemic lupus; a butterfly-shaped rash appears on face </li></ul>
  35. 36. APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 30.14 Allergic reactions can be debilitating and even fatal <ul><li>Allergies are hypersensitivities to substances, such as pollen, food, or animal hair, that ordinarily would do no harm to the body </li></ul><ul><ul><li>Response to antigens, called allergens, usually includes some tissue damage </li></ul></ul><ul><li>An immediate allergic response can occur within seconds of contact with the antigen </li></ul><ul><ul><li>The response is caused by antibodies known as IgE </li></ul></ul><ul><ul><li>When an allergen attaches to the IgE antibodies and the antibodies attach to their receptors on mast cells, the mast cells release histamine that bring about allergic symptoms </li></ul></ul><ul><ul><ul><li>Asthma , the airways leading to the lungs constrict, resulting in difficult breathing accompanied by wheezing </li></ul></ul></ul><ul><li>Anaphylactic shock - an immediate allergic response that occurs because the allergen has entered the bloodstream </li></ul><ul><ul><li>Characterized by a sudden and life-threatening drop in blood pressure </li></ul></ul><ul><li>Delayed allergic response is initiated by memory T cells at the site of allergen contact in the body </li></ul><ul><ul><li>Allergic response is regulated by cytokines secreted by both T cells and macrophages </li></ul></ul>
  36. 37. Figure 30.14 An allergic reaction
  37. 38. Connecting the Concepts: Chapter 30 <ul><li>The defense mechanisms of humans have been extensively studied, but little is known about these mechanisms in other animals </li></ul><ul><ul><li>Body has the skin and mucous membranes that act as barriers to prevent pathogens from entering the blood and lymph </li></ul></ul><ul><ul><li>Nonspecific defense mechanisms, such as the complement system and phagocytosis by white blood cells, come into play </li></ul></ul><ul><ul><li>Then, specific defense mechanisms, which are dependent on the activities of B cells and T cells, bring infection to an end </li></ul></ul><ul><li>The cardiovascular and lymphatic systems are intimately connected in that tissue fluid becomes lymph in lymphatic vessels, and is derived, in part, from the water and small molecules that leave the bloodstream </li></ul><ul><li>Blood is refreshed because the digestive, respiratory, and urinary systems make exchanges with the external environment </li></ul><ul><ul><li>The food we eat is digested into nutrients that enter the blood; gas exchange in the lungs permits the removal of carbon dioxide from blood and the entrance of oxygen into blood; and the kidneys remove and excrete metabolic wastes taken from the blood </li></ul></ul>