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26 terms

ap immunity

ap immunity
STUDY
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Types of Immunity
1. Nonspecific immunity - general defense against anything that is not "self"
2. Specific immunity - defense against specific threatening agents
Nonspecific Immunity
1. Mechanical and chemical barriers - first line of defense
2. Inflammation & phagocytosis - second line of defense
Phagocytosis
..
First Line of Defense: Barriers to entry - Physical
1. Physical
a. Intact skin
b. Mucous membranes
First Line of Defense: Barriers to entry - Chemical
1. Sebaceous gland secretions
2. Lysozyme in perspiration, saliva, and tears
3. Urine
4. pH of the stomach
5. Normal flora
Inflammatory Response: Cardinal signs
1. Redness (erythema) caused by hyperemia ( blood flow)
2. Swelling (edema) caused by capillary permeability and filtration
3. Heat caused by hyperemia
4. Pain caused by inflammatory chemicals (bradykinin, prostaglandins) secreted by damaged cells, pressure on nerves
Inflammatory Response: Defensive response to tissue injury
1. Limits spread of pathogens, then destroys them
2. Removes debris
3. Initiates tissue repair
4. Suffix -itis denotes inflammation of specific organs
Fever
1. Defense mechanism: does more good than harm
a. Promotes interferon activity
b. Accelerating metabolic rate and tissue repair
c. Inhibiting pathogen reproduction
2. > 105F may cause delirium, 111F- 115F, coma-death
Nonspecific Defenses
1. Natural killer cells - lymphocytes that kill tumor cells and cells infected by viruses
2. Interferon - protein synthesized and released by virally infected cells
3. Complement—group of enzymes that lyse cells
a. May be activated by specific or nonspecific mechanisms
Complement
1. Causes cytolysis
2. Causes vasodilation
3. Enhances phagocytosis
4. Can be stimulated by nonspecific immune responses as well as specific responses
Specific Immunity
1. B cells and Antibody-mediated immunity (humoral immunity)
2. T cells and Cellular immunity
3. Lymphocytes have antigen receptors
a. B lymphocytes
i. Mature in the bone marrow
ii. Give rise to plasma cells that produce antibodies
b. T lymphocytes
i. Mature in the thymus gland
ii. Directly attack cells that have nonself proteins or regulate the immune response
Lymphocytes have antigen receptors:
B lymphocytes
i. Mature in the bone marrow
ii. Give rise to plasma cells that produce antibodies
Lymphocytes have antigen receptors:
T lymphocytes
i. Mature in the thymus gland
ii. Directly attack cells that have nonself proteins or regulate the immune response
Antibody-Mediated Immunity
1. When B cells encounter an antigen they are activated to divide many times
a. Plasma cells - mature B cell that produces antibodies
b. Memory cells - make long-term immunity possible
i. A second exposure to the same antigen produces a stronger, faster immune response
2. Plasma cells undergo apoptosis when an infection has passed
Antibodies
1. IgM - Antibody of 1st response
2. IgG - Antibody of 2nd response
3. IgA - Secreted in saliva, tears, mucous membranes
4. IgE - Binds to mast cells & basophils
Stimulates inflammatory response
5. IgD - Antigen-binding receptors on B cells
Antibody Production: Primary response:
1. Occurs when a B cell is first activated by an antigen.
2. B cell proliferates to produce plasma cells (antibody production) and memory cells.
Antibody Production: Secondary response
1. Occurs during later exposure to same antigen.
2. Memory cells divide rapidly to form plasma cells and additional memory cells.
3. Faster and greater response.
Cellular Immunity
1. T cells attack foreign cells and diseased host cells
2. Memory of antigen
3. Three classes of T cells
a. Cytotoxic T cells carry out attack
b. Helper T cells: help promote cytotoxic T cell and B cell action and nonspecific defense mechanisms
c. Memory T cells: provide immunity from future exposure to antigen
Three classes of T cells
1. Cytotoxic T cells carry out attack
2. Helper T cells: help promote cytotoxic T cell and B cell action and nonspecific defense mechanisms
3. Memory T cells: provide immunity from future exposure to antigen
Helper T Cells Functions
1. Secretes interleukins
a. Attract neutrophils, NK cells, macrophages
b. Stimulate phagocytosis
c. Stimulate T and B cell mitosis and maturation
2. Coordinate humoral and cellular immunity
Types of Specific Immunity
1. Innate immunity
2. Acquired immunity
a. Natural immunity
i. Active immunity
ii. Passive immunity
b. Artificial or induced immunity
i. Active immunity
ii. Passive immunity
Hypersensitivity
1. Excessive immune reaction against antigens that most people tolerate - allergens
2. Autoimmunity
3. Alloimmunity
4. Allergy
a. Anaphylaxis
5. Mechanisms
a. Type I, type II, type III, and type IV
b. Immediate - occurs in minutes to a few hours
c. Delayed - may take several hours and are at maximum severity days after reexposure to antigen
IgE mediated reactions (type I)
1. Characterized by production of antigen-specific IgE after exposure to antigen.
2. Usually against environmental antigens (allergens)
3. Examples include : Allergic Rhinitis; Intrinsic Asthma; Anaphylactic Shock
Tissue specific reactions (type II)
1. Characterized by destruction of target cell through the action of antibody against an antigen on the cell's plasma membrane
2. Limited to tissue or organs that express tissue-specific antigen.
3. Transfusion reactions
4. Examples: Myastenia gravis, Grave's disease, Goodpasture's syndrome, and pernicious anemia.
Immune complex mediated injury (type III)
1. Most are caused by antigen-antibody complexes formed in circulation and deposited later in vessel walls or extravascular tissues.
2. Examples: Systemic Lupus Erythematosis; Rheumatoid arthritis; hypersensitivity pneumonitis; and acute glomerulonephritis
Cell medicated tissue destruction (type IV)
1. Mediated by specifically sensitized T lymphocytes and do not involve antibody.
2. Examples: Contact dermatitis, hypersensitivity pneumonitis, allograft rejection, type 1 diabetes mellitus, some forms of drug sensitivity, and thyroiditis.