system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does skin turn red when irritated?
gpt
The simple answer is that there is increased blood flow to the area of irritation. When you injure yourself, pro-inflammatory molecules are released that promote increased blood flow and attract a number of different types of cells to help heal and fight infection. When blood flow increases in part of your body, the area becomes red and warm.