Biochemistry & Immunology in Nursing Past Paper PDF 20/1/2025

20/1/2025 3 BIOCHEMISTRY & IMMUNOLOGY LEARNING OBJECTIVES IN NURSING (NRS414) AT THE END OF THE LESS...

20/1/2025 3 BIOCHEMISTRY & IMMUNOLOGY LEARNING OBJECTIVES IN NURSING (NRS414) AT THE END OF THE LESSON, STUDENTS ARE ABLE TO EXPLAIN OR IDENTIFY: I. The reactions of hypersensitivity type III and IV. II. The mechanism of auto-immune diseases. NRS421 HS240 HS260 4 5 Immune complexes consist of antigen and antibody bound together Usually adhere to Fc receptors on cells Complexes are destroyed and removed Certain instances complexes persist in circulation or at sites of formation Type III Hypersensitivities: Initiate blood clotting mechanism Activate complement contributing to inflammation Immune Complex Complexes commonly deposited in skin, joints and kidney Complexes also cause disseminated intravascular coagulation (DIC) Clots in small vessels Leads to system failure 6 7 Immune Complex (Type III) Hypersensitivity Results from the formation of antigen-antibody complexes that persist or are continuously formed Immune complex disorders are initiated after sensitization IgG antibodies combine with antigen in the blood to form an immune complex and activate complement Result: basophils and mast cells release histamine Antigen-antibody complex and other mediators of allergic reactions. Phagocytes release hydrolytic enzymes, causing tissue damage that is acute but can become chronic 1  20/1/2025 8 9 The Mechanism of Immune Complex (Type III) Hypersensitivity 10 11 12 13 2  20/1/2025 14 15 Type III Hypersensitivity Type IV Hypersensitivities: https://youtu.be/iY57dq7oU2U Delayed Cell-Mediated 16 17 Examples of Cell-Mediated Disorders Delayed hypersensitivities caused by cell- Contact Dermatitis: occurs in sensitized mediated immunity individuals on second or subsequent exposure to Slowly developing response to antigen allergens such as oils from poison ivy, rubber, certain metals, dyes, and soaps. Reactions peak in 2 to 3 days instead of minutes T cells are responsible for reactions Tuberculin hypersensitivity: occurs in sensitized Reactions can occur nearly anywhere in the body individuals exposed to tuberculin in a tuberculin skin test Delayed hypersensitivity reactions responsible for contact dermatitis, tissue damage, rejection Granulomatous hypersensitivity: most serious of tissue grafts and some autoimmune and usually occurs when macrophages have engulfed pathogens but have failed to kill them diseases 18 19 Contact hypersensitivities Mediated by the T cells T cells release cytokines Poison ivy (Type IV) Cytokines initiate inflammation that hypersensitivity attracts macrophages Macrophages release mediators Toxicodendron radicans to add to inflammation Showing leaves with Common examples of their characteristic three contact allergies include leaflets Poison ivy and poison oak Poison ivy vines contain Nickel in metal jewelry the irritating oil urushiol Chromium salts in leather Latex products 3  20/1/2025 20 21 Type IV Hypersensitivities: Delayed Cell-Mediated Poison Ivy Dermatitis, showing fluid-filled vesicles Tuberculin skin test Test involves introduction of small quantities of protein antigens from Mycobacterium tuberculosis into skin In positive skin test, injection site reddens and gradually thickens Reaction reaches peak in 2 to 3 days (48-72 hours) A reaction greater than 10 mm in diameter is considered positive Reactions result from sensitized T cells, release of cytokines and influx of macrophages 22 23 The Mechanism of cell-mediated, or delayed (Type IV), hypersensitivity 24 25 4  20/1/2025 26 27 Autoimmune Diseases Body usually recognizes self antigens Destroys cells that would destroy self Malfunction in immune recognition basis for Type IV Hypersensitivity autoimmunity https://youtu.be/mzC9NgY2Rj0 Autoimmune diseases may result from reactions to antigens that are similar to MHC self antigens Autoimmunity may occur after tissue injury Self antigens released from injured organ Autoantibodies form and interact with injured tissues 28 29 Autoimmune Diseases Spectrum of autoimmune diseases Reactions occur over spectrum Organ-specific to widespread responses Organ-specific Thyroid disease Only thyroid is affected (Hyperthyroidism, Hashimoto Thyrodism) Widespread response Lupus Autoantibodies made against nuclear constituents of all body cells Rheumatoid arthritis Immune response made against collagen in connective tissue 30 31 Autoimmune Diseases 5  20/1/2025 32 Autoimmune Disease https://youtu.be/vDwNpDT-8L0 Examples of Autoimmune Disorders Myasthenia gravis Myasthenia gravis Usually are chronic inflammatory disorders with symptoms that can alternately worsen and lessen Myasthenia gravis: usually affects skeletal muscles of limbs, eye movements, speech, and swallowing Principle symptoms: progressive weakness and muscle fatigue Muscle contraction is prevented by IgG autoantibodies that either block the acetylcholine receptor or cause a reduction in number of receptors 36 37 Myasthenia gravis (MG) is a chronic autoimmune disorder that results in progressive skeletal muscle weakness. MG causes rapid fatigue (fatigability) and loss of strength upon exertion that improves after rest. Myasthenia gravis is caused by a defect in the transmission of nerve impulses to muscles. Normally when impulses travel down the nerve, the nerve endings release a neurotransmitter substance called acetylcholine. In myasthenia gravis, antibodies produced by the body’s own immune system block, alter, or destroy the receptors for acetylcholine. 6  20/1/2025 38 39 Myasthenia gravis https://youtu.be/kBmQrZJBQCQ 40 41 Rheumatoid Arthritis Rheumatoid Arthritis: Joint inflammation is typical in people suffering from this autoimmune disorder Affectsmainly joints of hands and feet, although it can extend to other tissues Characterized by inflammation and destruction of cartilage in the joints, often causing deformities in the fingers Cause is unknown, but some researchers believe that an infectious microbe (mycoplasma or virus) is the cause, leading to antigenic mimicry and attack of self antigens 42 43 Systemic Lupus Erythematous (SLE) Lupus Erythematosus: A systemic autoimmune disease The characteristic butterfly-shaped rash of SLE Name is derived from the reddened skin rash that resembles a wolf’s mask In SLE, autoantibodies (IgG, IgM, IgA) are made primarily against components of DNA, but can also be made against blood cells, neurons, and other tissues Result: Anti-DNA antibodies attack the remnants of cells, cause inflammation and interfere with normal functioning at these sites 7  20/1/2025 44 45 Lupus erythematosus: Characteristic butterfly-shaped rash of SLE. Appears white in dark-skinned people Sytemic Lupus Erythematosus (SLE) https://youtu.be/0junqD4BLH4 8