Essentials of Pathophyslology Part 2

TABLE 19.1 Types of Hypersensitivity Type of Reaction Time Before Clinical Signs Characteristics Examples Type I (Anaphylactic) 15-30 min IgE binds to mast cells or basophils, causing degranulation with release of chemical mediators; mediators include histamine, leukotrienes, and prostaglandins; systemic reaction Anaphylactic shock from drug injection and insect stings; common allergic conditions, such as hay fever and asthma Type II (Cytotoxic) 5-12 hours IgG or IgM antibodies bind to target cell when combined with action of complement; destroys target cell Transfusion reactions, Rh incompatibility Type III (Immune Complex) 3-8 hours Antibodies and antigens form complexes that cause damaging inflammation Arthus reaction, serum sickness Type IV (Delayed Cell-Mediated, or Delayed Hypersensitivity) 24-48 hours Antigens activate T cells that damage target cell Rejection of transplanted tissues; contact dermatitis, such as poison ivy; some autoimmune diseases   Review the differences between benign and malignant tumors. -> Benign: * o More closely resembles original tissue type * o Grows more slowly * o Little vascularity * o Rarely necrotic * o Often retains original function * o Rarely fatal, does not evade, many are encapsulated - [illegible] from [illegible] -> Malignant: * o ignore cell growth controlling signals, proliferate - [illegible] * o escape signals to die and achieve a kind of immortality - [illegible] * o display lack of differentiated features (anaplasia), contribute poorly or not at all to function of their tissue * o greater degree of anaplasia = more aggressive malignant tumor -> Metastatic -> Necrotic What are the three steps of carcinogenesis? -> Carcinogen: potential cancer-causing agent Initiation - mutation to chromosomes or DNA occurs (radiation, UV, carcinogens) [Highlighted in yellow] Promotion - mutated cell proliferates (carcinogen) [Highlighted in yellow] Progression - mutant, proliferating cells begin to exhibit malignant behavior, permanent changes - [illegible] Review the effects of cancer on the body including terms: cachexia, anemia, leukopenia, and thrombocytopenia. -> Pain: possible result of metastasis, tissue destruction/inflammation   -> Cachexia: overall weight loss and generalized weakness * o loss of appetite * o increased metabolic rate -> chemotherapy, radiation * o N/V * o Bone marrow suppression: caused by invasion and destruction of bone marrow cells, poor nutrition and chemotherapy - contributes to anemia, leukopenia and thrombocytopenia   -> Anemia: deficiency in circulating RBCs -> cold, fatigue, pallor, tired -> Leukopenia: deficiency in circulating WBC's -> [illegible] the risk of infection -> Thrombocytopenia: deficiency in circulating platelets -> [illegible]   Review the various infections of the skin discussed in class including: warts, herpes simplex virus, herpes zoster, fungal infections, impetigo   -> Warts: common benign papillomas caused by papillomaviruses * o thickened composition of skin * o treatment: * surgical removal by laser * liquid nitrogen * cryotherapy or salicylic acid paint/plaster * topical blistering agents * immunomodulators * intralesional injections   -> Herpes Simplex Virus: two types: HSV-1 (lips, face and mouth) & HSV-2 (genital area) * o usually begin with a burning or tingling, followed by vesicles and erythema, crusts before healing * o treatment: * no cure, analgesics for pain, antivirals to shorten duration of outbreaks -> Herpes Zoster: shingles- acute localized inflammatory disease along a dermatomal segment of the skin caused by varicella zoster (chickenpox) * o results from reactivation of the latent virus * o eruption of painful vesicles with erythematous bases typically unilateral, causes paresthesias * o treatment: * antiviral drugs, preferably within 48 hours, vaccination for prevention   -> Fungal Infections: typically grow in warm, moist places * o manifests as a circular, erythematous rash accompanied by pruritus and burning * o reddened plaques with peripheral scaling and central clearing (think ringworm) * tinea capitis (scalp) * tinea corporis (body) * tinea pedis (feet, especially toes)