The cuts are red, but the bruises have a whole range of colors. When a person is cut, blood flows out of the body through the wound until it coagulates and closes the cut. But a bruise is an injury in which the blood does not flow quickly. When a person hits something, blood gushes from the injured tiny capillaries under the skin. Spilled blood collects at the site of injury. Meanwhile, blood components, such as platelets, which are responsible for clotting, try to stop minor bleeding in order to prevent major damage.
The redness seen in bruises is hemoglobin, a red pigment in red blood cells that has accumulated under the skin. Darker colors (almost black, purple and blue) represent a kind of optical illusion. The light that encounters red hemoglobin is reflected and refracted through many thin layers of skin, so it seems to us that it is more blue than it really is. Hemoglobin decomposes in about a week and loses its bright red color (it becomes brownish). That is why the light that is reflected from it contains more yellow overtones, and the bruise, while pale, looks green, yellow and brown. Some bruises may take two weeks or more to heal and disappear completely. People with thin skin get bruises more easily than those with thicker skin. In women, they occur more often because each layer of skin in men is thicker than the corresponding layer of skin in women. Also, the older a person is, the thinner and weaker his skin is, which is why many older people can get terrible bruises even from minor injuries. Every person has thin skin on some parts of the body. For example, there is little protective fatty tissue between the skin and bones around the eyes or on the shins and knees, which would mitigate the consequences. That is why a punch to the eye makes such a terrible black and blue bruise, and a fall from a bicycle on shins and knees can leave a real colorful chaos.
There is a simple and really effective way to stop bruises before they appear. Immediately after the blow, the painful place should be pressed with the lower part of the palm (the pressure should last for a few minutes). That alone may be enough to prevent the appearance of an ugly bruise. Then ice should be placed on the injured area. These methods are effective because the pressure stops the bleeding immediately, and the ice collects the blood vessels so that further bleeding and swelling are reduced. If the bruise still appears, you should wait approximately 48 hours until it fully develops, and then warm it, for example with a warm towel. This will lead to fresh blood to the bruise, which will absorb and take away the damaged cells.
Food can also help prevent bruising. Citrus fruits (oranges, lemons, etc.), tomatoes, broccoli and other foods with a lot of vitamin C can help. Vitamin C strengthens capillaries throughout the body, so it is recommended that those who easily get bruises take 1000 mg of vitamin C daily – 500 mg in the morning and 500 mg in the evening.
Interesting fact: bruises on the legs take the most time to pass because higher blood pressure in the legs causes heavier bleeding.