Skin mucosa red and purple

The skin and mucous membranes protect the human body, so that the human body forms a closed system to the outside world. When harmful substances are about to invade the human body, the skin and mucous membranes first block external pathogenic factors outside the body. Therefore, the skin and mucous membranes are the first line of defense for the body against infection. However, if the amount of harmful substances invaded exceeds the tolerance of the mucous membranes, it will cause redness, swelling and discoloration of the skin and mucous membranes.