Final answer:
The skin can become flushed and red due to inflammation caused by infections, injuries, exercise, or immune responses to conditions such as acne.
Step-by-step explanation:
The skin can become abnormally flushed and red for several reasons, with inflammation being a central cause. Inflammation is a bodily response to infections or injuries, releasing chemicals that dilate local blood vessels, increase blood flow, and attract white blood cells, leading to redness. Exercise can also cause skin redness due to the dilation of arterioles in the dermis, allowing heat to dissipate. Similarly, infections in the lymphatic system, such as lymphangitis and lymphadenitis, trigger an inflammatory response, which can result in red streaks and swollen lymph nodes under the skin. Vasodilation due to inflammatory mediators like histamine increases capillary diameter, contributing to the heat and redness experienced during inflammation. Conditions like acne involve blocked pores and bacterial growth, with the subsequent immune response leading to inflammation, swelling, redness, and possibly the formation of pus.