NR507_Advanced_Pathophysiology_Edapt_Notes.2023 newest update

NR507_Advanced_Pathophysiology_Edapt_Notes.2023 newest update Advanced Patho Edapt Notes Week 1: Immune System • Hypersensitivity Reactions o The immune system functions to eliminate pathogens from the body using various mechanisms ▪ Pathogens are bacteria, viruses, and other microorganisms o These mechanisms typically create a localized inflammatory response that effectively eliminates the pathogen with minimal damage to the surrounding tissues o Individuals also come in contact with numerous foreign bodies (plant pollen, food) o Contact with these environmental antigens does not normally elicit an immune response in a majority of individuals o However, in predisposed individuals the immune system can mount a response to environmental antigens, resulting in tissue damage that ranges from mild irritation to life threatening anaphylactic shock o These immune responses are referred to as allergic reactions or hypersensitivity reactions o Hypersensitivity reactions can be divided into 4 categories • Type I: Allergic Reaction o On initial encounter with an allergen, the individual will produce IgE antibodies o Once the allergen is cleared, the remaining IgE bind to mast cells, basophils, and eosinophils that contain receptors for IgE ▪ This process is referred to as sensitization o When re-exposed to to the allergen the IgE located on the sensitized cells induce immediate degranulation o Degranulation causes the release of inflammatory mediators, such as histamine, leukotrienes, and prostaglandins that result in vasodilation, bronchial smooth muscle contraction, and mucus production o Type I reactions can be local or systemic ▪ Systemic reactions can result in anaphylaxis ▪ Local reactions can produce rash, hives, itching o Allergic asthma is an example of a type I reaction • Type II Hypersensitivity o Tissue-specific and usually occurs as a result of haptens that cause an IgG or IgM antibody mediated response o The antibodies are specifically directed to the antigen located on the cell membrane o Haptens are small molecules that can cause an immune responses when it attaches to a protein o Macrophages are the primary effector cells of type II responses o The type II response begins with the antibody binding to the antigen and may cause the following: ▪ The cell to be destroyed by the antibody ▪ Cell destruction through phagocytosis by macrophages ▪ Damage to the cell by neutrophils triggering phagocytosis ▪ Natural killer cells to release toxic substances that destroy the cell ▪ Malfunction of the cell without destruction o Examples of type II reactions ▪ Drug allergies ▪ Hemolytic anemia ▪ Blood transfusion mismatch with resulting transfusion reaction and Rh hemolytic disease • Type III Immune-Complex Reaction