Chapter 12- The Lymphatic System and Body Defenses

Transcription

1 Chapter 12- The Lymphatic System and Body Defenses I. The Lymphatic System a. Consists of two semi-independent parts i. Lymphatic vessels and Lymphoid tissues and organs b. Lymphatic system functions i. Transport back to the blood ii. Play essential roles in body and resistance to disease c. Lymphatic Characteristics i. excess tissue fluid and fats carried by lymphatic vessels ii. Properties of lymphatic vessels 1. One way system toward the heart- have to prevent backflow 2. No pump- Lymph moves toward the heart 3. Milking action of moves fluid 4. Rhythmic contraction of muscle in vessel walls d. Lymphatic Vessels i. Lymph 1. Walls overlap to form flap-like mini-valves, Fluid leaks into lymph capillaries 2. Capillaries are anchored to connective tissue by filaments 3. Higher pressure on the inside closes mini-valves ii. Lymphatic collecting vessels 1. Collects lymph from lymph capillaries, Carries lymph to and away from lymph nodes 2. to circulatory veins near the heart 3. Right lymphatic duct and Thoracic duct iii. Lymph 1. Materials returned to the blood a. Water, Blood cells, Proteins b. Harmful materials that enter lymph vessels-bacteria, Viruses, Cancer cells, Cell debris iv. Elephantiasis Symptoms- 3. Treatment-

2 v. Lymph Nodes 1. Filter lymph before it is returned to the blood 2. Defense cells within lymph nodes a. engulf and destroy foreign substances b. provide immune response to antigens 3. Lymph Node Structure a. Most are kidney-shaped, less than 1 inch long b. i. Outer part- Contains follicles collections of lymphocytes c. i. Inner part- Contains phagocytic macrophages d. Lymph enters the convex side through afferent lymphatic vessels e. Lymph flows through a number of sinuses inside the node f. Lymph exits through efferent lymphatic vessels g. Fewer efferent than afferent vessels causes flow to be slowed 4. Lymphoma Symptoms- Treatment- e. Several other organs contribute to lymphatic function i. The Spleen 1. Located on the left side of the abdomen 2. Filters, Destroys worn out blood cells, Forms blood cells in the fetus, Acts as a blood 3. Mononucleosis a. b. Symptoms- c. Treatment- ii. Thymus 1. Located low in the throat, overlying the heart 2. Functions at peak levels only during childhood 3. Produces hormones (like thymosin) to program iii. Tonsils 1. Small masses of lymphoid tissue around the pharynx 2. and remove bacteria and other foreign materials 3. Lingual tonsils are on the tongue 4. Pharyngeal tonsils (adenoids) are in the upper pharynx 5. Palatine tonsils are those you can see in the back of the throat 6. Trap and remove bacteria and other foreign materials 7. Strep throat a. b. Symptoms- c. Treatment-

3 iv. Peyer s Patches 1. Found in the wall of the small 2. Resemble tonsils in structure- Capture and destroy bacteria in the intestine 3. E Coli infectiona. b. Symptoms- c. Treatment- v. Bone Marrow 1. Site of 2. Forms red blood cells, white blood cells and platelets 3. Leukemiaa. b. Symptoms- c. Treatment- vi. Mucosa-Associated Lymphatic Tissue (MALT) 1. Includes: a. Peyer s patches, Tonsils, Other small accumulations of lymphoid tissue b. Acts as a sentinel to protect respiratory and digestive tracts I. Body Defenses A. The body is constantly in contact with bacteria, fungi, and viruses B. The body has two defense systems for foreign materials 1. defense system 2. defense system a) Mechanisms protect against a variety of invaders b) Responds immediately to protect body from foreign materials 3. Nonspecific Body Defenses a) Body surface coverings, Intact skin, Mucous membranes, Specialized human cells, Chemicals produced by the body b) Surface Barriers First Line of Defense (1) The (a) Physical barrier to foreign materials, ph of the skin is acidic to inhibit bacterial growth (acid mantle), Sebum is toxic to bacteria (2) Vaginal secretions are very acidic (3) Stomach -Secretes hydrochloric acid, has protein-digesting enzymes (4) and lacrimal fluid contain lysozyme (a) Mucus traps in digestive and respiratory pathways, wax in the ears (b) Nasal hairs, ear hairs filter and trap microorganisms (c) Cilia in the respiratory passages propel harmful substances up and out of the respiratory tract (d) Urine is slightly acidic, inhibiting bacterial growth and cleansing the lower urinary tract c) Defensive Cells (i) (neutrophils and macrophages) (a) Engulfs foreign material into a vacuole (b) Enzymes from lysosomes digest the material

4 (2) Natural cells (a) Damaged cells send out warning proteins (b) Natural killer cells are attracted to these (c) Can and kill cancer cells and can destroy virusinfected cells d) Inflammatory Response - Line of Defense (1) Triggered when body tissues are injured (2) Produces four cardinal signs (a) Redness, Heat, Swelling, Pain (3) Results in a chain of events leading to protection and healing (4) Functions of the Inflammatory Response (a) Prevents of damaging agents (b) Disposes of cell debris and pathogens, Sets the stage for (c) Prevents spread of damaging agents e) Antimicrobial Chemicals (1) (a) Secreted proteins of virus-infected cells (b) Bind to healthy cell surfaces to inhibit viruses binding f) Fever (1) Abnormally high body temperature (2) Damaged cells secrete. The hypothalamus senses these and resets the temperature to a higher level. (3) High temperatures inhibit the release of iron and zinc from liver and spleen needed by (4) Fever also increases the speed of tissue

5 First Lines of Defense 4. Specific defense system- Line of Defense a) Specific defense is required for each type of invader b) Also known as the system c) Antigen specific recognizes and acts against particular foreign substances d) Systemic not restricted to the initial infection site e) Has memory recognizes and mounts a stronger attack on previously encountered pathogens f) Types of Immunity (1) immunity= Antibody-mediated immunity (i) Cells produce chemicals for defense (2) immunity= Cell-mediated immunity (i) Cells target virus infected cells g) (Nonself) (1) Any substance capable of exciting the immune system and provoking an immune response (2) Examples of common antigens (a) Foreign proteins, Nucleic acids, Large carbohydrates (b) Some lipids, Pollen grains, Microorganisms h) Self-Antigens (1) Human cells have many proteins (2) Our immune cells do not attack our own (3) Our cells in another person s body can trigger an immune response because they are foreign (4) Restricts donors for (5) Organ Transplants and Rejection (a) Major types of grafts grafts tissue transplanted from one site to another on the same person grafts tissue grafts from an identical person (identical twin) grafts tissue taken from an unrelated person grafts tissue taken from a different animal species Autografts and isografts are ideal donors Xenografts are never successful Allografts are more successful with a closer tissue match

6 II. f. Allergies 1. Many small molecules (called or incomplete antigens) are not antigenic, but link up with our own proteins 2. The immune system may recognize and respond to a protein-hapten combination 3. The immune response is harmful rather than protective because it attacks our own cells Cells of the Immune System- Originate from in the red bone marrow B lymphocytes become immunocompetent in the bone marrow T lymphocytes become immunocompetent in the thymus Arise from and become widely distributed in lymphoid organs 1. (Antibody-Mediated) Immune Response a. B lymphocytes with specific receptors bind to a specific antigen b. The binding event activates the lymphocyte to undergo clonal selection c. A large number of clones are produced ( humoral response) d. Most B cells become plasma cells e. Produce antibodies to destroy antigens f. Activity lasts for four or five days g. Some B cells become long-lived memory cells ( humoral response) h. Secondary Response i. cells are long-lived ii. A second exposure causes a rapid response iii. The secondary response is stronger and longer lasting Immunity Your B cells encounter antigens and produce antibodies Active immunity can be naturally or artificially acquired

7 Immunity Antibodies are obtained from someone else Conferred naturally from a mother to her fetus Conferred artificially from immune serum or Immunological memory does not occur Protection provided by borrowed antibodies 2. Antibodies ( ) (Igs) a. Soluble proteins secreted by B cells (plasma cells) b. Carried in blood plasma c. Capable of binding specifically to an antigen d. Antibody Function o) (Cell-Mediated) Immune Response p) After antigen binding, clones form as with B cells, but different classes of cells are produced e. T Cells i. Specialize in killing infected cells f. T Cells i. Recruit other cells to fight the invaders ii. Interact directly with B cells g. T Cell Clones i. T cells 1. Release chemicals to suppress the activity of T and B cells 2. Stop the immune response to prevent uncontrolled activity

8 Disorders of Immunity: Allergies (Hypersensitivity)- Abnormal, vigorous immune responses b. Types of allergies i. Immediate Triggered by release of histamine from IgE binding to mast cells 1. Reactions begin within seconds of contact with allergen c. shock dangerous, systemic response Anaphylaxis Cause Symptoms III. Treatment d. Delayed hypersensitivity i. Symptoms usually appear 1 3 days after contact with antigen Disorders of Immunity: a. AIDS- Acquired Immune Deficiency Syndrome Cause Symptoms Treatment b. SCID- Severe Combined Immune Deficiency Cause Symptoms IV. Treatment Disorders of Immunity: Diseases a. The immune system does not distinguish between self and non-self b. The body produces antibodies and sensitized T lymphocytes that attack its own tissues c. Examples of autoimmune diseases i. Multiple white matter of brain and spinal cord are destroyed Symptoms- Treatmentii. gravis impairs communication between nerves and skeletal muscles iii. Juvenile destroys pancreatic beta cells that produce insulin iv. arthritis destroys joints Symptoms- Treatmentv. impairment of renal function vi. Systemic erythematosus (SLE) Symptoms- Treatment-