Final answer:
The four cardinal signs of inflammation are redness, swelling, heat, and pain, with altered function as a possible fifth sign. These result from increased blood flow and the actions of inflammatory mediators like histamine after tissue injury or infection.
Step-by-step explanation:
Cardinal Signs of Inflammation
The four most common indicators and major symptoms of an acute inflammatory response include erythema (redness), edema (swelling), heat, and pain. A fifth indicator often associated with inflammation is altered function or loss of function. These symptoms arise due to the body's innate immune response to tissue injury or infection. When cells are damaged, they release substances like histamine, leukotrienes, and prostaglandins. Histamine in particular causes vasodilation, leading to increased blood flow and capillary permeability, resulting in the warmth and redness associated with inflammation. The increased permeability allows fluid to leak into tissues, causing swelling. In addition, inflammatory mediators along with the influx of white blood cells can stimulate pain receptors, causing the pain observed during inflammation. The resulting physical barrier of cells and fluids also serves to contain the area of injury, attempting to prevent the spread of infection.
Fever is another systemic sign of inflammation. It raises body temperature and is a reaction that stimulates the immune response beyond the local inflammation signs.