Local inflammation is outwardly seen as pain, redness, loss of function, swelling and heat. The redness and heat seen with inflammation is due to . Dilation of blood vessels at the body’s surface brings blood from the core to the site of injury. An increase in the number of red blood cells at the surface gives the skin a pink-red appearance in areas that are not hair covered, and the blood carries heat from the body’s core to the site of injury. Swelling is caused by the movement of fluid from the blood vessels to the tissues. This occurs as a result of increased vascular permeability. First transudate, then exudate accumulates in the intracellular space, which puts pressure on the surrounding structures and nerve endings, causing pain. Pain and swelling in combination result in the loss of function. When considering tissues whose function is under conscious control, we can see that if moving or using a body part increases the sensation of pain the individual would prefer not to use that body part. When considering an area whose function is under involuntary control, it is generally the effects of swelling that impair normal cell function, though there may be pain associated with that area. Systemic inflammation is seen as , leukocytosis, shift to the left, tachycardia, tachypnea, anorexia, weight loss, nausea or lethargy. Every individual in every instance of systemic inflammation may not exhibit all symptoms, but in most cases, pyrexia is at least evident if there is a systemic inflammatory reaction.
Stages of Inflammation
Inflammation can be categorized as either acute or chronic based on the duration and presentation of symptoms. Acute inflammation usually occurs suddenly in response to the sudden necrosis of multiple body cells. In addition to the rapid onset, acute inflammation is characterized by the activation of tissue macrophages and by neutrophilia. Acute inflammation is generally an intense inflammatory response with pain, redness, loss of function, swelling and heat all being evident. The chemical mediators that predominate in an acute inflammatory response are histamine, leukotriene and prostaglandins. An acute inflammatory reaction will last only as long as the source of injury persists. Usually acute inflammation is resolved in a matter of days. Chronic inflammation tends to be a less intense reaction but is a prolonged and persistent process. Usually chronic inflammation occurs in response to repeated, low-grade injury or repeated mechanical stress. The symptoms of chronic inflammation are less pronounced than those in acute inflammation and may not reflect the extent of tissue damage clearly. Macrophages, lymphocytes and plasma cells predominate a chronic inflammatory reaction. The chemical mediators involved in chronic inflammation are the cytokines such as interleukin-I, growth factors, reactive species of oxygen (free radicals) and digestive enzymes. Subacute inflammation can be thought of as a prolonged acute reaction. In subacute inflammation, we see the symptoms and leukocytes of an acute reaction, with some of the mediators of a chronic reaction. Subacute inflammatory reactions may revert into an acute reaction or may progress to become chronic.
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