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30 Cards in this Set
- Front
- Back
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Innate Immunity Components |
Anatomic: skin and mucous membranes Physiologic: temperature, low pH Phagocytic/Endocytic: granulocytes Inflammatory: Rubor=redness Tumor=swelling Calore=tissue heating Dolore=pain |
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Inflammatory Response |
Dilute Destroy Isolate Initiate repair |
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Dilute |
Vasodilation: Warmth and redness, opens microvascular beds, increased intravascular pressure Vascular permeability: swelling, transudate gives way to exudate, increases interstitial osmotic pressure contributing to edema |
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Destroy |
Extravision: rolling, activation, arrest, migration Chemotaxis: follow chemical gradient to site of injury |
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Role of Neutrophils |
Phagocytosis: granules containing bactericidal agents and enzymes that join with the phagosome to digest foreign matter Repiratory Burst: formation of reactive O2 species in intracellular granules Secretion of Chemical Mediators: secrete cytokines |
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Macrophages |
Second cell on scene; In blood- monocyte; monocytes enlarge to form tissue macrophages, dominant cell types after first few days; role is to destroy, more sustainable killing capacity |
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Acute vs Chronic Inflammation |
Acute: rapid onset; relatively short diration; exudation of fluid and plasma proteins; predominantly neutrophils Chronic: delayed onset; longer duration; associated histologically with the presence of lymphocytes and macrophages, the proliferation of blood vessels, fibrosis, and tissue necrosis |
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Granulation Tissue |
There to isolate and initiate repair; characterized histologically by a pebbly, granular appearance; neovascularization; proliferation of fibroblasts |
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Resolution of Inflammation and Wound Healing |
Extrusion: material forced out of the body Resorption: no fibrous capsule formation or collapse/replacement of fibrous capsule Integration: close approximation of host tissue to the implant with no intervening fibrous capsule Encapsulation: traditional reponse to non-resorbable materials ISOLATE |
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Fibrous Encapsulation |
Final stage of healing for implants; maturation of granulation tissue--> larger blood vessels and alignment of collagen fibers Degree depends on: original injury, amount of cell death, location, degradation of implant Thickness depends on: amount of small particulates produced, mechanical factors, shape of implant, electrical currents |
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Repair vs Regeneration |
Resolution: dead cells & cellular debris are removed by phagocytosis Regeneration: damaged tissue is replaced by cells of the same type Repair: original tissue is replaced with scar tissue |
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Roles of Adaptive Immunity |
Immune Surveillance Recognition (self vs non-self) Activation: proliferation and differentiation of responding cells Effector Response: generation of a protective response Memory |
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Innate Immunity Interacts with Adaptive Immunity |
Innate immunity precedes and directs the subsequent response of adaptive immunity Adaptive immunity then uses the compoonents of innate immunity to clear invading agents |
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Recognition |
Antigen: any molecule recognized by specific antibodies or T cells Immunogen: induce a specific immune response |
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Surveillance |
T lymphocytes test cells secret handshake Antigen-presenting cells bring information to T cells at lymph nodes b cells can detect intact antigens and act as APCs to bring information to T cells |
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Types of Rejection |
Hyperacute Acute Cellular Acute Humoral Chronic |
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Hyperacute Rejection |
Allergic reaction; occurs when the recipient has previously been sensitized to the donor tissue Rejection starts within minutes Relatively rare now Type I: IgE mediated- allergen Type II: Antibody Mediated- complement Type III: Immune Complex Mediated Type IV: T-cell mediated |
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Hapten |
small molecule that can elicit an immune response only when attached to a large carrier such as a protein |
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Acute Cellular Rejection |
Characterized by the development of an acquired immune response to the grafted tissue Develops within days-weeks after transplantation This is the major target for immunosuppresion after transplants |
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Acute Humoral Rejection |
Characterized by the production of antibodies against the donor tissue by the recipient Usually causes complement-mediated cell damage and severe thrombosis within transplanted organ Treatment involves IVIG or rituximab and/or plasmapheresis; splenectomy is sometimes necessary |
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Biomaterial Adjuvant Effect |
Biomaterial component acts as an adjuvant to the immune response towards foreign antigens by: 1. promoting an inflammatory response 2. recruiting and activating antigen-presenting cells (macrophages, dendritic cells) |
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Histology/IHC |
amount of lymphocytes present around material |
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Blood samples |
presence of circulating antibodies |
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Skin testing |
localized inflammation due to allergic reactions |
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Biocompatibility |
The ability of a material to perform with an appropriate host response in a specific application Identification of the causal relationships between materials and host tissue such that materials can be designed to elicit the most appropriate response |
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Biocompatibility assessment |
measurement of the magnitude and duration of the adverse alterations in homeostatic mechanisms that determine the host response |
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Appropriate Host Response |
Depends on the implant site and the nature of the material Certain reactions may be acceptable depending on the application |
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In vitro experiments |
In vitro test minimize the use of animals in research; is required by most regulatory agencies in device approval process; provides useful insights that can dictate whether a device needs to be further evaluated in expensive in vivo models |
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In vivo experiments |
Goal is assessment of tissue compatibility to determine the biocompatibility or safety of the medical device in a biological environment |
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Designing Animal Testing |
Choose animal model that offers a reasonable parallel anatomically or biochemically minimize the number of animals treat humanely maximize relevant information cost not sufficient rationale |
