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What are the 2 "parts" of the lymphatic system?
- Lymphatic Vessels
- Lymphatic Tissues and Organs
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What does the lymphatic system do?
- Transport fluids back to the blood
- Body defense and resistance to disease
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What is lymph?
Excess fluid carried by lymphatic vessels
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What are the properties of lymphatic vessels?
- One way system towards the heart
- No pump
- Moves fluid by milking action of the skeletal muscles and rhythmic contraction of smooth muscle in vessel walls
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How do lymph capillaries work?
- Walls overlap to make flap like mini valves
- High pressure on the inside closes valves
- Fluid leak into lymph capillaries
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What are lymph collecting vessels?
- Vessels that collect lymph from capillaries
- Carry lymph away from lymph nodes
- Returns fluids to circulatory veins near the heart
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What are the 2 lymph ducts?
- Right lymphatic duct
- Thoracic duct
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What materials are returned to the blood?
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What harmful materials enter the lymph vessels?
- Bacteria
- Viruses
- Cancer Cells
- Cell Debris
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What do the lymph nodes do, and how?
- Filter lymph before its returned to the blood
- Macrophages engulf and destroy foreign substances
- Lymphocytes provide immune response to antigens
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What is the structure of a lymph node?
- Cortex - outer part containing follicles (collection of lymphocytes)
- Medulla - Inner part containg phagocytic macrophages
- Less than 1 inch long
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How does lymph flow through nodes?
- Enters afferent lymphatic vessels
- Flows through sinuses
- Exits efferent lymphatic vessels
- Fewer efferent than afferent causes back-up
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What are the "other" lymphoid organs?
- Spleen
- Thymus
- Tonsils
- Peyer's Patches
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What does the spleen do?
- Filters bloood
- Destroys worn out blood cells
- Forms blood cells in the fetus
- Acts as a blood reservoir
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What does the thymus do?
- Produces hormones to program lymphocytes
- Functions at peak levels during childhood
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What do the tonsils do?
- Trap and remove bacteria and other foreign materials
- Tonsillitus is caused by bacterial congestion
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What do Peyer's Patches do?
Capture and destroy bacteria in the small intestine
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What are Mucosa-Associated Lymphatic Tissues (MALT)?
- Protects respiratory and digestive tracts
- Peyer's Patches
- Tonsils
- Other small lymphoid accumulations
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What is the body's 2 systems for defense against foriegn materials?
- Nonspecific defense system - protects against a variety of invaders, responds immediately
- Specific defense system - immune system, specific defense required for each type of invader
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What are nonspecific body defenses?
- Surface coverings - skin, mucous membranes
- Specialized human cells
- Chemicals produced by the body
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What is the skin?
- Physical barrier to foreign materials
- pH of skin is acidic to inhibit bacterial growth
- Sebum is toxic to bacteria
- Vaginal secretions are very acidic
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What does the stomach mucosa do?
- First line of defense
- Secretes hydrochloric acid
- Has protien digesting enzymes
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What are the defensive cells of the lymphatic system?
- Phagocytes - neutrophils and macrophages
- Engulfs foriegn material into vacuoles
- Enzymes from lysozyme digest material
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What do phagocytes do?
- Lyse and kill cancer cells
- Destroy virus-infected cells
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What is the lymphatic systems second line of defense?
- Inflammatory Response
- Triggered when body tissues are injured
- Redness
- Heat
- Swelling
- Pain
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What are the functions of inflammatory response?
- Prevents spread of damaging agents
- Disposes of cell debris and pathogens
- Sets the stage for repair
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What is fever?
- High body temperature
- Increases speed of tissue repair
- Inhibit release of iron and zinc from liver that bacteria need
- Hypothalmus reset by pyrogens
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What is the immune system?
- Antigen specific defense
- Systemic - not limited to infection site
- Has memory - recognized and mounts stronger attack the next time there is infection
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What are the types of immunity?
- Humoral - antibody mediated, cells produce chemicals for defense
- Cellular - cell mediated, cells target virus infected cells
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What are antigens (nonself)?
- Substance capable of igniting an immune response
- Foreign particles
- Nucleic acids
- Large carbohydrates, and some lipids
- Pollen grains
- Microorganisms
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What are self-antigens?
- Human cells have many surface protiens
- Body usually doesn't attack itself
- Our cells in another persons body could cause an immune response
- Limits donors for transplants
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What are allergies?
- Small molecules that bind with our own cells
- The immune system is harmful due the body attacking its own cells
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What are the cells of the immune system?
- Lymphocytes - B lymphocytes bone morrow, T lymphocytes thymus
- Macrophages - arise from monocytes, widely distributed in lymph organs
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Characteristics of humoral immune response:
- B lymphocytes bind to specific antigens
- Large number of clones are produced
- Most B cells become plasma
- Produce antibody's to destroy antigens
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What is a secondary response?
- Memory cells are long lived
- Rapid response
- Secondary response is stronger and longer lasting
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What is active immunity?
- B cells enounter antigens and produce antibodies
- Naturally or artifically acquired
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What is passive immunity?
- Antibodies obtained from someone else
- Naturally from mother to child
- Artifically from immune serum or gamma globulin
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What are monoclonal antibodies?
- Antibodies prepared for clinical testing, produced from a single cell line
- Diagnose pregnancy and treatment for hepatitis and rabies
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What are antibodies?
- Soluable protiens secreted by B cells
- Carried in blood plasma
- Binds specifically to an antigen
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What is the structure of an antibody?
- Four amino acid chains linked by disulfide bonds
- Two identical amino acid chains are linked to form a heavy chain
- Two identical chains are light chains
- Specific antigen binding sites are present
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5 antibody classes:
- IgM - fix complement
- IgA - mainly in mucus
- IgD - activation of B cells
- IgG - can cross placental barrier
- IgE - involved in allergies
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How do antibodies inactivate antigens?
- Complement fixation
- Neutralization
- Agglutination
- Precipitation
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How does cell mediated immune response work?
- Antigens must be presented by macrophages to an immnocompetent T Cell
- T cells must recognize nonself and self
- After antigen binding, different classes of cells are produced
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3 types of T-Cell clones
- Cytotoxic T cells - kill infected cells, insert toxic chemical
- Helper T cells - Recruit other cells to fight, interact with B cells
- Supressor T cells - keeps immune response from overacting
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4 types of grafts:
- Autografts - tissue transplant on same person
- Isograts - tissue transplant from identical twin
- Allografts - tissue taken from unrelated person
- Xenografts - tissue taken from different animal species
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Types of hypersensitivities:
- Immediate hypersensitivity - IgE, reacts in seconds, anaphalactic shock
- Delayed hypersensitivity - T cells, reacts within 1 - 3 days
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Immunodeficiencies
- Congenitcal or acquired
- Includes Aids
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Autoimmune Diseases:
- Immune system does not distinguish "self"
- T lymphocytes attack own tissues
- Multiple Sclerosis
- Juvenile Diabetes
- Rheumatoid Arthritis
- Systemic Lupus
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