Cardinal signs of inflammation
Chapter: 2
Rubor (redness); dolor (pain); calor (heat - but only of skin and extremities, because the underlying cause is movement of blood at the body's core temperature to areas that are environmentally cooled); tumor (swelling); and functio laesa (loss of function). Redness is caused by increased blood flow to the site, due to the action of mediators, axon reflex, and local increase in the hydrogen ion concentration. Heat is also due to increased blood flow and greater local cellular metabolism. Swelling is the result of increased blood flow, edema, infiltration of cells, and the proliferation of connective tissue in subacute-to-chronic lesions. Pain is due to the direct effects of mediators such as prostaglandin and the stretching of sensory nerves due to swelling. Loss of function is due to replacement of parenchymal tissue (e.g., damaged myocardium); reflexive disuse, due to pain; and mechanical, as when a joint either swells during acute inflammation or scar tissue that bridges it contracts as it matures in a chronic lesion.