Chapter 13 Lecture Outline

Transcription

1 Chapter 13 Lecture Outline See separate PowerPoint slides for all figures and tables preinserted into PowerPoint without notes. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1

2 13.1 Lymphatic System 2

3 A. Functions of the Lymphatic System 1. Fluid balance takes up excess tissue fluid and returns it to the blood stream 2. Fat absorption from the digestive tract into lacteals and transports them to the blood stream 3. Defense works with the immune system to protect against disease 3

4 B. Lymphatic vessels 1. Form a one-way system 2. Begins with lymphatic capillaries a. Tiny, closed-ended vessels b. Take up excess tissue fluid (lymph) 3. Vessels merge and then enter one of two ducts that enter the right and left subclavian veins a. Thoracic duct drains the left side of the head, left chest, left arm, and the lower body b. Right lymphatic duct drains the right side of the head, right chest, and right arm 4. Vessels have valves and movement of lymph depends on skeletal muscle contraction 5. Edema is localized swelling caused by the accumulation of lymph 4

5 The lymphatic system 5

6 13.2 Organs, tissues, and cells of the immune system 6

7 A. Introduction 1. The immune system is a network of lymphatic organs, tissues, and cells, as well as products of the cells 2. Immunity the ability to react to antigens to remain free of disease 7

8 B. Primary lymphatic organs 1. Lymphocytes originate and/or mature in these organs 2. Red Bone Marrow a. Site of stem cells that produce blood cells b. In an adult, red bone marrow is found in the sternum, vertebrae, ribs, skull, part of the pelvic girdle, and proximal heads of the humerus and femur c. Lymphocytes differentiate into B and T lymphocytes and natural killer (NK) cells 1) B lymphocytes mature in the red bone marrow 2) T lymphocytes mature in the thymus 8

9 Primary lymphatic organs, cont 3. Thymus Gland a. In the thoracic cavity b. Largest in children and shrinks as a person ages c. Lobules are filled with lymphocytes d. Produces thymic hormones called thymosins 1) Aids in maturation of T lymphocytes 2) May have other functions in immunity e. Functions is critical to immunity 9

10 C. Secondary lymphatic organs 1. Places where lymphocytes encounter and bind with antigens 2. Spleen a. Largest lymphatic organ b. Consists of two types of tissue: 1) White pulp has a concentration of lymphocytes 2) Red pulp surrounds venous sinuses and is involved in filtering blood c. Blood entering the spleen is filtered through venous sinuses 1) Lymphocytes and macrophages react to pathogens 2) Macrophages engulf debris and remove old red blood cells 10

11 Secondary lymphatic organs, cont 3. Lymph nodes a. Small structures occurring along lymphatic vessels b. Forms a capsule of connective tissue c. Node is divided into compartments 1) Contains nodules packed with B lymphocytes and macrophages 2) Sinus that contains T lymphocytes d. Lymph passing through the sinus is filtered by macrophages e. T lymphocytes fight infection and attack cancer cells 11

12 Secondary lymphatic organs, cont 4. Lymphatic nodules a. Concentrations of lymphatic tissue not surrounded by a capsule b. Tonsils in the pharynx and oral cavity c. Peyer patches in the wall of the small intestine d. Appendix attached to the large intestine 12

13 13.3 Nonspecific and specific defenses 13

14 A. Nonspecific Defenses 1. Barriers to entry a. Physical 1) Intact skin 2) Mucous membranes and cilia b. Chemical 1) Sebaceous gland secretions 2) Lysozyme in perspiration, saliva, and tears 3) Urine 4) ph of the stomach 5) Normal flora 14

15 2. Inflammatory reaction a. Four signs due to capillary changes in damaged tissue 1) Redness 2) Heat 3) Swelling 4) Pain 15

16 b. Steps of inflammatory reaction 1) Chemical mediators, such as histamine, cause capillaries to dilate and become more permeable a) Excess blood causes redness and increased temperature 2) Increased permeability causes fluids and proteins to escape the capillaries and cause swelling and pain 3) Edema and clot formation wall off the area 4) Migration of phagocytes (monocytes and neutrophils) 5) Monocytes become macrophages that devour pathogens and debris 16

17 Steps of inflammatory reaction 17

18 Nonspecific Defenses, cont 3. Natural killer cells a. Kill virus-infected cells and tumor cells b. Large, granular lymphocytes c. No specificity and no memory 18

19 4. Protective proteins a. Complement 1) Composed of blood plasma proteins 2) Activated when pathogens enter the body 3) Amplify the inflammatory response 4) Bind to the surface of pathogens, ensuring that they will be phagocytized 5) Form a membrane attack complex that punches holes in the walls and membranes of bacteria b. Interferon 1) Produced by virus-infected cells 2) Produce substances that interfere with viral replication 19

20 Three Lines of Defense 20

21 B. Specific Defenses 1. Introduction a. Respond to antigens and distinguishes from self-antigens b. Lymphocytes have antigen receptors 1) B lymphocytes a) Mature in the bone marrow b) Give rise to plasma cells that produce antibodies 21

22 Introduction to specific defenses, cont 2) T lymphocytes a) Mature in the thymus gland b) Directly attack cells that have nonself proteins c) Regulate the immune response by producing cytokines 22

23 2. B cells and antibody-mediated immunity a. Also called humoral immunity b. Clonal Selection 1) When B cells encounter an antigen they are activated to divide many times 2) Clones a) Most mature to form plasma cells (with the same antigen receptor) that produce antibodies b) Some become memory cells 1) Make long-term immunity possible 2) A second exposure to the same antigen produces a stronger, faster immune response 3) Plasma cells undergo apoptosis when an infection has passed 23

24 Clonal selection theory and B cells 24

25 c. Structure of antibodies 1) Basic unit is a Y-shaped protein molecule with two arms (4 protein strands) 2) Chains have constant regions at the trunk of the Y that determines the antibody class a) Monomers single Y-shaped molecules b) Dimers paired Y-shaped molecules c) Pentamers clusters of 5 Y-shaped molecules linked together 3) Variable region forms an antigen binding site with a specific shape to match an antigen 25

26 Structure of a single antibody 26

27 d. Function of antibodies 1) Neutralization covering toxins on surface membranes 2) Forming immune complexes to enhance phagocytosis 3) Activation of complement for cell lysis or phagocytosis 27

28 Functional classes of antibodies 28

29 3. T cells and cell-mediated immunity a. Antigen must be presented to T cells by an antigen-presenting cell (macrophage or B cell) b. Major histocompatability (MHC) proteins 1) Called HLA (human leukocyte antigens) 2) Are self proteins c. T cell compares the antigen and the self protein 1) Activated T cell and all daughter cells can recognize foreign from self 2) Will destroy cells carrying foreign antigens 29

30 Clonal selection theory and T cells 30

31 d. Types of T cells 1) Cytotoxic T cells (CD 8 leukocytes) a) Destruction of virus-infected or cancer cells b) Have storage vacuoles containing Perforin molecules c) Perforin punches holes in the plasma membrane causing cell lysis d) Responsible for cell-mediated immunity 2) Helper T cells (CD 4 leukocytes) regulate immunity by secreting cytokines that stimulate various immune cells to perform their functions 31

32 Types of T cells, cont 3) Memory T cells provide a faster response to an antigen that had previously been present in the body 4) Cytokines in Cancer Chemotherapy a) Used as immunotherapeutic drugs to enhance the ability of T cells to fight cancer b) Interferon and interleukins are also used as immunotherapeutic drugs 32

33 Cell-mediated immunity 33

34 13.4 Creating an immune response 34

35 A. Active immunity 1. Natural active immunity a. Actual exposure to the antigen b. Primary response occurs c. Generally get sick d. Make antibodies and memory cells 2. Artificial active immunity a. Involves the use of vaccines to cause a primary response b. Generally do not get sick c. A second exposure produces a faster and larger secondary response 35

36 Vaccine responses 36

37 B. Passive immunity 1. Natural passive immunity a. Occurs when a mother passes antibodies to a child through the placenta or mother s milk b. Temporary no memory cells 2. Artificial passive immunity a. Occurs when an individual is given prepared antibodies (immunoglobulins) b. Is temporary no memory cells c. Can be used in the event of an unexpected exposure to an infectious disease 37

38 C. Monoclonal antibodies 1. Every plasma cell derived from the same B cell 2. Secretes antibodies against one antigen 3. Can be produced in vitro using myeloma cells 4. Are being used for quick and certain diagnosis of various conditions 5. Used to carry radioactive isotopes or toxic drugs to tumors 38

39 Production of monoclonal antibodies 39

40 D. Hypersensitivity reactions 1. Allergies a. Response to substances that are usually harmless to the body (allergens) b. IgE-Mediated Allergic Response 1) Immediate allergic response 2) Caused by IgE antibodies 3) When an allergen attaches to the IgE antibodies, histamine is released 4) Anaphylactic shock occurs when the allergen has entered the blood stream causing vasodilation and extreme drop in blood pressure 40

41 Allergies, cont c. T-Cell Mediated Allergic Response 1) Delayed allergic response 2) Initiated by memory T-cells at the site of allergen contact 3) Regulated by cytokines 4) Examples contact dermatitis, TB test 41

42 2. Tissue rejection a. Transplanted tissue is recognized as not self b. Cytotoxic T cells cause disintegration of the transplanted tissue c. Can be controlled by: 1) Selecting organs that have the same type of HLA antigens as those of the recipient 2) Administering immunosuppressive drugs such as cyclosporine or tacrolimus 42

43 3. Autoimmune diseases a. Cytotoxic T cells or antibodies attack the body s own cells b. Cause is unknown; some are hereditary c. Examples: 1) Myasthenia gravis 2) Multiple sclerosis 3) Systemic lupus erythematosus 4) Rheumatoid arthritis 5) Type 1 diabetes 6) Crohn s disease 7) Ulcerative colitis d. No cures, but can be managed with medications 43

44 E. Immune deficiency 1. The immune system is unable to protect the body from disease 2. Can be acquired or genetic 3. Without treatment, common infections can be fatal 4. Examples AIDS and SCID 44

45 13.5 Effects of Aging 45

46 Effects of Aging A. Aging people become more susceptible to infections and disorders B. Thymus gland degenerates and number of T cells decreases C. B cells sometimes do not form clones D. Antibodies do not function as well E. Incidence of autoimmune diseases increases F. Response to vaccines is decreased 46

47 13.6 Homeostasis 47

48 Homeostasis A. The lymphatic system helps the following: 1. The digestive system by absorbing fat 2. The cardiovascular system by absorbing lymph 3. The immune system in protection against infectious diseases B. Nonspecific immune responses are dependent on: 1. The skin 2. Mucous membranes of the respiratory tract, the digestive tract, the reproductive and urinary systems C. Specific defenses are dependent on blood cells D. There is a strong connection between the immune, nervous, and endocrine systems 48

49 Human systems work together 49