Pathophysiology

Pathophysiology Study Guide

the skin. Some features of inflammation are redness in the skin as the blood vessels get dilated, heat caused by an increase in the flow of blood, swelling due to fluid leaking from small blood vessels, and pain and itching. It is also possible that the affected area on the skin gets indurated due to the deposition of the coagulated protein fibrin. Additionally, affected blood cells get infiltrated. With vascular changes, the skin’s inflammatory response takes the form of whealing reactions, like hives, nettle rash, or urticaria. In this situation, the inflammatory cellular reaction generally does not take place. In short-lived wheals, localized fluid is accumulated and leads to intense itching, while intense inflammation leads to blisters due to the release of enzymes from the inflammatory cells or blood plasma components, which breakdown the proteins in the skin responsible for maintaining the structural integrity of skin. The inflammatory response of the derma may be acute (for instance, hemolytic streptococcal infections in which the blood cells are destroyed, which leads to inflammation in the connective tissues), or chronic (for instance, lupus vulgaris). The acute inflammatory response generally shows no physical change in the skin, while the chronic inflammation response makes the skin thick and hard, which under the microscope, appears brown in color. Allergic Response An allergic response is caused when an allergen triggers the immune system response. There are many different types of allergic responses to skin disorders. Some of these are briefed below: • Hives and angioedema: Also known as Urticaria, this leads to the formation of redness, itchiness, and raised skin. They may appear on any part of the skin and are generally mild. However, in severe cases, chronic hives are developed, which shows a trend of appearing and disappearing and may last for years. Angioedema are often formed in conjunction with hives and involve swelling in the deeper layers of the skin. The most affected areas are the eyelids, lip, tongue, hands, and feet. Hives and angioedema are generally caused by viral infections, bacterial infections, insect stings, food or drug reactions, or environmental factors like cold, heat, exposure to sunlight, and exercise. • Atopic dermatitis: This is also known as eczema and mostly affects children. It is caused by weakness in the skin barrier. It can also be triggered by food sensitivities. People with filaggrin often suffer from chronic atopic dermatitis. Diseases associated with atopic dermatitis are hay fever, food allergies, and asthma. • Allergic contact dermatitis: This is caused by contact with poison ivy. Allergic contact dermatitis leads to itching, redness, and the formation of blisters. These reactions generally show after one or two days and take two to three weeks to heal. The major cause of this disorder is a substance called urushiol, which is a chemical element present in plants. Other substances that may cause allergic contact dermatitis are nickel, dyes, latex, and perfume. Neoplastic Another response, and one of the most severe, is the formation of skin cancers. Cutaneous neoplasms

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