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42 Cards in this Set
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3 Functions of the lymphatic system
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The production, maintenance and distribution of lymphocytes to provide defense.
Lymphocytes provide "specific defense" Consists of lymphatic vessels lymphatic tissues lymphatic organs |
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Function of Lymphatic vessels
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Present in all tissues with blood supply except bone marrow and central nervous system
Cary lymph from peripheral tissues to vein Lymphatic capillaries Small Lymphatic vessels Major lymph collecting vessels foreign things exist in lymph - therefore they won't be in the marrow or cns in order to prevent infection. |
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Features of Lymphatic Capillaries
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Originate as pockets opposed to cappillaries which branch off arteries etc.
Have a large diameter and thinner walls than capillaries Have a flattenned or irregular outline of cross section |
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Features of small lymphatic vessels
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Structure similar to veins with overlapping endothelial cells.
Have valves to prevent backflow (like veins) Valves are close together via overlapping endothelial - things get in - not out. Commonly occur in association with blood vessels Pale golden color in live tissues |
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Features of major lymph collecting vessels
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Two sets of lymphatic vessels
Superficial lymphatics – subcutaneous; mucous membranes and serous membranes On the skin Deep lymphatics – accompanying deep arteries and veins accompany arteries and veins All Converge to form lymphatic trunks and empty into Thoracic duct Right lymphatic duct |
Thoracic trunk drains 75% of body and the right lymphatic duct drains the right arm and right half of chest and head.
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Lymphocytes . . .
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Main character of lymph system
Thymus-dependent (T) cells ~ 80% circulating cells -cell mediated Cytotoxic T cells – attack virus infected cells Regulatory T cells – 2 types helper - gets it going suppressor - says "enough is enough" to the helpers Natural Killer Cells - -attack vrius infected cells ____________________________ Bone marrow-derived (B) cells ~ 10%-15% circulating cells -humeral (fluid) mediated Production of antibodies Natural Killer (NK) cells Attack virus infected cells |
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Lymphocytes circulation and life span
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T cells move relatively quickly
Stay in one place for only hours B cells stay in a lymph node for minimum tens of hours ~80% of lymphocytes survive 4 years Some last 20+ years |
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Lymphocyte production. . .
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Lymphocytes come from lymphoid (original blast cell) *stem cells in bone marrow*
B cells and NK cells mature in bone marrow Lymphoid stem cells migrate to thymus and mature to T cells Out of bone marrow, lymphocytes can divide and reproduce |
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Lymphoid Tissues
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Lymphoid tissues - connective tissues dominated by lymphocytes
Lymphoid nodule – lymphocytes densely packed in an area of areolar tissue Germinal centers contain dividing lymphocytes |
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MALT. . .
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Mucosa-associated lymphoid tissue
Clusters of lymphoid nodules deep to the mucosal epithelial lining various sites of the body Abundant in the gastrointestinal epithelium (e.g.: Peyer’s patches in small intestines) Most abundantly found in intestines |
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Tonsils. . . .
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Large lymphoid nodules in the walls of the pharynx
Three types: Palatine tonsils - visible Pharyngeal tonsil - In the middle (adenoid) (also visible - up near nasal area) Lingual tonsils - at base of tongue and not normally visible |
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Lymphoid organs. . .
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Lymph nodes
Thymus - Spleen |
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Lymph nodes. . .
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Up to an inch in diameter
Covered by dense connective tissue Fibrous connective tissue extended into interior of the node – trabeculae Blood vessels enter from hilus Afferent lymphatics and efferent lymphatics (afferent means toward and efferent means go out) |
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Histology of a lymph node. . .
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Lymph enters Subcapsular sinus – dendritic cells initiate immune response
flows through Outer cortex – (B cells present inGerminal center) flows through the Deep cortex then into Medulla --> efferent lymphatics |
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Function of a lymph node. . .
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Filters lymph before it enters the vein
>99% of the antigens are removed |
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Lymph glands. . .
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Large lymph nodes located where peripheral lymphatics connect with the trunk
In the groin, the axillae and the base of the neck Injury produces enlargement of the nodes is called “swollen glands” |
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Thymus. . .
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Located posterior to the sternum
Grows to its maximum size (~40 g) by puberty and gradually diminishes (involutes) Covers the aorta and superior vena cava |
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Structure of a thymus. . .
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Two lobes
Fibrous partitions, (septa) divide the lobes into lobules Densely packed outer cortex T cells mature here (Not all - only cytotoxic T cells) Paler central medulla |
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Thymosins. . .
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A group of hormones produced by thymus to help t cells mature. (7 have been found)
Important to the development and maintenance of normal immunological defenses |
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Spleen. . .
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Largest collection of lymphoid tissue
Performs the same functions for blood that lymph nodes for lymph Remove abnormal blood cells Storage of recycled iron Initiation of immune responses by B cells and T cells <-- they didn't realize this back in the day VERY soft (like liver but softer) Doesn't hold sutures well Can use topical coagulants (powders, mesh - like used in boxing) Splenectomy : - not often performed anymore unless absolutely necessary - Risk of bacterial infection with pneumocococcal bacteria - Patients with a spelenctomy require pneumovax vaccinne |
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Histology of the spleen. . .
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Red pulp – contains large quantities of red blood cells
White pulp – resembles lymphoid nodules Capillaries discharge blood into red pulp Blood flows through mesh structure with phagocytes Empties into venous system |
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Body defense. . .
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Specific Defenses---
--- protect against particular threats --- Dependent on lymphocytes --- Lymphocytes produce immunity Non-specific defenses: physical barriers (skin) - prevent approach and deny access to pathogens phagocytes - remove debris and pathogens interferon - increase resistance of cells to viral infection and slow the spread of disease complement system - attacks and breaks down cell walls attracts phagocytes stimulates inflammation inflammatory response Multiple effects mast cells (see slide on mast cells) fever - mobilizes defenses accelerates repairs inhibits pathogens |
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Properties of immunity. . .
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Specificity – activated by a specific antigen and responds to that particular antigen
Versatility – responds to millions of antigens Memory – ready to combat the second time Tolerance – will not attack the antigens in own body --- lack of tolerance is found in auto immune disorders. |
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Antigen presentation. . .
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Antigen must bind to special glycoproteins in the cell membranes to trigger the immune response
- glycoproteins are on the T cells -antigen hooks up to them -glycoproteins are coming from DNA (couple of steps in between) Major Histocompatibility Complex gene controls synthesis of MHC protein (On chromosome 6) ---- this is the glycoprotein. Two types: Class I – self-identification - On all cells Class II – defense against intruders MHA II Major histocompatability proteins on membranes of "antigen presenting cells" (apc's) [ie. phagocytic cells& lymphocytes] Antigenic fragments attach to MHC II proteins in cytoplasm, comlplexes move to plasma membrane where T cells are activated. |
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T cells. . .
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Cytotoxic T cells – seek out and destroy abnormal and infected cells
(Type 1) - how virus is killed. Memory T cells – set aside for secondary response (think as watching from the sidelines) Suppressor T cells – “Off timer” They limit the response of t cells - keep a body from attacking itself. Helper T cells – messengers that secrete cytokines to stimulate other defense cells |
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Auto-immune disorders. . .
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Immune system attacks own normal tissues
Hashimoto thyroiditis (antibodies against thyroglobulen) Rheumatoid arthritis (auto-antibodies form immune complexes in the joints) Insulin-dependent diabetes mellitus (autoantibodies attack cells in pancreas that make insulin) |
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Immunodeficiency. . .
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Severe combined immunodeficiency disease – “bubble boy”
AIDS Side effect of medication |
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Allergies. . .
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Inappropriate or excessive immune responses
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Aging and immune responses. . .
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With advanced age, the immune system becomes less effective
T cells become less responsive Reduced numbers of T cells Involution of the thymus Reduction in levels of thymic hormones |
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Complement System
Classical pathway |
Uses anti-body
comes from B cells anti-body binds to bacterial wall (antigen) Protein comes and attaches to anti-body Ultimately activation of C3B - Activation of c3B is most important part. |
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Complement system
Alternate pathway |
Also results in C3b
Other factors activate the c3b No protein or anti-body's are involved |
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What happens after c3B activation?
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beginning of destruction of the cell
stimulation of phagocytosis multiple pores in the bacterium cell is lysed |
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Signs and symptoms of inflammation
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tumor (swelling)
rubor (red) calor (hot) dolor (pain) |
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Cycle of tissue damage
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Tissue is damaged
Chemical change in interstitial fluid mast cells release : histamine (increases vessel permeability and secretion and dilates blood vessels) and heparin (attraction phagocytes especially neutrophils) which release cytokines |
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innate immunity
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genetically determined
no prior exposure or production involved 1 of 2 choices in specific resistance. Ends here. |
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Acquired immunity
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produced by prior exposure or antibody production.
Leads to either Active immunity or passive immunity |
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active immunity
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produced by antibodies that develop in response to antigens (immune response)
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Active immunity leads to what two types?
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Induced active immunity (develops after administration of antigen)
or Naturally acquired active immunity (develops after exposure to antigens in environment. |
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Passive immunity leads to what two types?
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Natural acquired passive immunity (conferred by transfer of maternal antibodies across placenta or in breast milk
or Induced passive immunity (conferred by administration of antibodies to combat infection) Used in treating someone with Rabies |
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Passive immunity defined:
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produced by transfer of antibodies from anther person.
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The two prone immune response:
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Antigens come into body -->
Specific defenses kick in --> splits into either cell-mediated immunity or antibody mediated immunity. |
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During cytotoxic t cell acivation
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two thirds are turned into active killer cells
one third is turned into memory cells for additional go around of infection |
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