305189 lymphatic-system


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305189 lymphatic-system

  1. 1. Lymphatic System Composition Lymph Lymphocytes Lymph vessels Lymph nodes Tonsils Spleen Thymus gland Function 1) Maintains fluid balance - 30 liters of plasma pass out of capillaries each day - 27 liters get resorbed at capillary - 3 liter left in tissue spaces get resorbed into lymph vessels 2) Fat absorption from gastrointestinal tract - lacteals in small intestine - lymph + fat = chyle (a milky white fluid) 3) Body defense system - lymph nodes filter lymph contains lymphocytes - spleen filters blood Lymph Vessels Carry lymph away from tissues begins at lymph capillaries (simple squamous epithelium) lymph capillaries join together to form vein-like lymph vessels lymph vessel contain valves to prevent retrograde flow o contraction of skeletal muscle o smooth muscle in lymph vessel wall o pressure changes in thorax during breathing 1) Right Lymphatic Duct (RLD) drains lymph from - right upper limb - vessels from right halve of head, neck, & chest form the RLD which empties into the right subclavian vein. 2) Thoracic Duct The rest of the body drains into the Thoracic Duct which empties into the left subclavian vein. Lymphatic Lecture Page 1
  2. 2. Lymph Organs - Contain lymphatic tissue composed of lymphocytes, macrophages, & other cells. - Lymphocytes originate from red bone marrow, and are carried by the blood to lymph organs. - Microorganisms stimulate lymphocyte cell division in germinal centers of lymph nodes. This is called Immune System Activation 1) Tonsils Protects body against pathogens entering at the nose and mouth. a. palatine ⠓ posterior oral cavity b. pharyngeal âr“ nasal cavity, adenoids c. lingual âe “ posterior tongue 2) Lymph Nodes - Small, round structures along lymph vessels. - Lymph passes through at least one node before emptying into vein. - Superficial aggregation Inguinal in groin Axillary Cervical The function of a node is to filter lymph and produce lymphocytes. 1) activation of the immune system (lymphocyte cell division) 2) phagocytosis of pathogens by macrophages 3) Spleen Located in the left upper abdominal cavity Function: Filters blood of pathogens and old RBCs Activation of immune system Blood reservoir Easily traumatized 4) Thymus Located in the superior mediastinum Function: Maturation of lymphcytes Lymphatic Lecture Page 2
  3. 3. Defense or Resistance Ability to resist damage from foreign substances. Two kinds of defense. 1) Nonspecific Resistance constant response time versus 2) Specific Resistance faster & faster response time 1) Nonspecific Resistance: Identical response time for repeat infections. Example; each time a bacterium enters the body, it is phagocytized with the same speed & efficiency. 2) Specific Resistance: The response for repeat infections is faster and more efficient due to the ability to recognize (specificity) and remember a particular antigen. Specific resistance also imparts long lasting immunity from a pathogen, so it is also called Specific Immunity. 1) Nonspecific Resistance A. Mechanical Mechanisms for preventing entry - skin & mucous membranes - tears, saliva, urine wash out microorganisms - ciliated mucous membranes in lungs - coughing and sneezing remove from respiratory tract B. Chemical Mediators (4), bring about or focus immune system response 1. Lysozyme in tears and saliva 2. Histamine promotes inflammatory response by vasodilating and increasing capillary permeability (producing edema & swelling) 3. Compliment Eleven proteins in plasma are inactive, but are activated by bacteria or antibodies. Active compliment promotes - Inflammation - Phagcytosis - Attracts WBCs - Lysis of bacterial cells Lymphatic Lecture Page 3
  4. 4. Nonspecific Resistance Chemical Mediators (cont.) 4. Interferons are proteins from infected cells that protect uninfected cells from viral infection. Virus Infected Cell Interferons Uninfected Cell More viruses Cell death Antiviral Proteins C. Cells, all WBCs except lymphocytes White blood cells are the most important cellular component of the immune system. Histamine and compliment attract WBCs. - neutrophils (phagocytes) first to arrive - macrophages are monocytes that have left blood vessels (5x bigger) - basophils release histamine - mast cell (not a WBC) in connective tissue release inflammatory chemicals - eosinophils release chemicals that break down inflammatory chemicals Lymphatic Lecture Page 4
  5. 5. 2) Specific Resistance (a.k.a Immunity) Due to an antibody/antigen reaction. Specific resistance is the ability to recognize, respond, and remember a particular antigen. Molecules which stimulate specific resistance are called antigens. 1) Foreign Antigens - parasites - bacteria - viruses - toxins (chemicals) 2) Self Antigens - tumors - autoimmune disease multiple sclerosis rheumatoid arthritis **Specific resistance results from lymphocyte activity!!** Two types of Lymphocytes 1. B cells produce proteins called antibodies. Thus, antibody mediated immunity is the result of B cells or B lymphocytes activity. 2. T cells are contact killers. They lyse invading cells on contact. Thus, cell mediated immunity is the result of T cells or T lymphocytes. Lymphatic Lecture Page 5
  6. 6. I. Antibody Mediated Immunity (B-cell) Works well for extracellular antigens. A. Primary Response Antigen binds to receptor on B lymphocyte. B lymphocyte + Antigen Plasma Cells + Memory B Cells (Provides long lasting immunity) Antibodies Primary response takes 3-14 days. B. Secondary Response Memory B cells are responsible for the secondary response for a repeat infection. 1. faster response time, will produce antibodies within a few hours 2. more effective response, many more antibodies are produced Lymphatic Lecture Page 6
  7. 7. II. Cell Mediated Immunity (T-cell) Can work for intracellular antigens. A. Primary Response Antigen binds to receptor on T lymphocyte. Cytotoxic T Cells 1) promotes inflammation 2) promotes phagocytosis 3) contact killing Memory T Cells (long lasting immunity) Primary response takes 3-14 days. B. Secondary Response Memory T cells are responsible for the secondary response for a repeat infection. 1. faster response time, will produce cytotoxic T cells within quickly 2. more effective response, many more cytotoxic T cells are produced Lymphatic Lecture Page 7