By Regina Bailey. Definition: Homeostasis is the ability to maintain a constant internal environment in response to environmental changes. It is a unifying principle of biology. The nervous and endocrine systems control homeostasis in the body through feedback mechanisms involving various organs and organ systems.
Urticaria is the medical term for a type of allergic rash. Hives are the most common type of urticaria. Hives are itchy, pink to light red, raised blotches that are usually one-quarter to one-half inch in size.Hives can occur on any part of the body.ives are the most common type of urticaria. Hives are itchy, pink to light red, raised blotches that are usually one-quarter to one-half inch in size. Hives can occur on any part of the body.
1 Typically, the hives are a reaction to food, but in about half the cases, the trigger is unknown. 2  Common foods may be the cause, as well as bee or wasp stings, or skin contact with certain fragrances. 3  Acute viral infection is another common cause of acute urticaria (viral exanthem).