Pathophysiology

Pathophysiology Study Guide

Histamine is a common chemical mediator, stored in the granules of mast cells and basophile white cells, which is released from cells and triggers vasodilation. This helps enhance the permeability of blood vessels. Other chemical mediators helpful in increasing vascular permeability are lysosomal compounds and cytokines. Some fatty acids, like prostaglandins, also increase vascular permeability and influence the aggregation of platelets, which is helpful in the clotting process. Finally, the plasma secretes four protein systems that act as mediators of inflammation: complements, kinins, coagulation factors, and fibrinolytic system. Following acute inflation, there may be a number of outcomes, including: • Healing and repair: The damaged cells that have the ability to proliferate generally regenerate during healing. Cells differ regarding regeneration capability. For instance, epithelial cells proliferate easily, as compared to the liver cells, which are stimulated only after damage has happened. It also depends on the structure of the body, that is, flat structures regenerate easier than complex structures. It is also possible that when proliferation fails, it leads to the development of some disease, like liver cirrhosis, wherein the damaged tissues regenerating form abnormal structures, which can lead to hemorrhage and even death. A fibrous scar is made when the damage is immense and regeneration is not possible. In the process of repair, new blood vessels are formed from endothelial cells, which later on form into loose connective tissues, known as granulation tissue. After this, blood is circulated into the healing area and granulation tissues gain mechanical strength collagen, which leads to the formation of scars formed from densely packed collagen. • Chronic inflammation: If the agent that is causing inflammation is not removed or the healing process cannot be successful due to some interference, the acute inflammation progresses and leads to chronic inflammation. Chronic inflammation is also possible if the person suffers from repeated periods of acute inflammation. Chronic inflamed diseases include tuberculosis, chronic lung diseases, and rheumatoid arthritis. The cause of chronic inflammation can be pathogens carrying infections or environmental factors, which cannot be removed by phagocytosis. Rheumatoid arthritis develops when the immune system of the body has become sensitized and has autoimmune reactions. Another kind of chronic inflammation disease is granulomatous inflammation, in which small collections of altered macrophages surrounding lymphocytes, known as granulomas, are developed. A classic instance of granulomatous inflammation is tuberculosis in which tubercles are formed. Systemic Manifestation: Sometimes the injury is not confined to the localized area, and the whole body detects the threat. The defense mechanism, systemic manifestation, is characterized by an acute-phase response, such as fever or lethargy. Causes for systemic inflammation are surgical complications, burn, drug overdose, infection, and trauma. Symptoms of systemic inflammatory response vary from mild to severe depending on the severity of the reaction. It is facilitated by bacteria stimulating cytokines, such as LPS and other inflammatory stimuli. With systemic inflammation, the pyrogens trying to stimulate the synthesis of prostaglandin in the

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