You may have noticed that when your skin gets damaged, whether it's from shoes that don't fit, a cut, or acne (yes, most of us have had it at some point) your skin gets red. That's your body sending blood to the area to help fight infection and heal the area.

Arteries take blood away from the heart. Veins take blood back to the heart. These blood vessels are really just for transporting blood to and from the tiniest blood vessels, which are the capillaries. That's where the real action takes place. The walls of the capillaries are very thin, so things pass through the walls easily. Capillaries deliver oxygen, sugar and nutrients to cells and pick up carbon dioxide and lots of other wastes. The cells of your immune system also travel in the blood (as well as other ways).

Skin cells divide a lot faster than cells in your liver, for example, so they need to copy their DNA a lot. Sunlight contains high-energy ultraviolet (UV) light that can mess up the DNA. When you damage your skin by exposing it to too much sun, the capillaries get larger so that they can deliver more blood to the skin. This allows the immune cells to get there and provides energy and raw materials to start the process of repairing your skin.

If your skin is naturally darker, you can still get sunburned, it just takes longer. Your skin may not look red, but it will get darker due to the increase in blood flow.

Too much sun can lead to skin cancer and wrinkles later in life, but too little sun is also a problem. Do you have any ideas on why everyone should get some sun? For a hint, look at a container of milk. Why is there vitamin D added?

Your blood rushes to the surface where you are burned as a response to the damage inflicted. I do not know what causes the blood to come to the surface, but it is what causes your skin to take on a red color.