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Bruise

life science Maturity 11-13 Next article →

A bruise is a type of internal bleeding called a contusion.

Blåmärken
Blåmärken

It happens when blunt trauma, like a hit or a fall, damages your body. This trauma causes physical compression or deceleration forces. These forces break tiny blood vessels called capillaries. When they break, blood leaks into the surrounding interstitial tissues. This blood stays under the skin instead of escaping through it. If the skin breaks, it is called a hemorrhage instead of a bruise.

Sprained foot
Sprained foot

Most bruises happen close to the surface of the skin. This makes the bleeding easy to see as a color change.

There is a specific way a bruise works inside your body. First, the damaged capillary endothelium releases a hormone called endothelin. This hormone narrows the blood vessel to help stop the bleeding. Next, the broken vessel exposes a factor called von Willebrand factor. This helps start coagulation, which is the way your body makes a clot. This clot acts like a plug for the wound.

US Army Vet Injury
US Army Vet Injury

As time passes, your immune system works to clear the blood away. The bruise stays visible until the tissues absorb the blood or the immune system removes it.

Scientists use different names to describe different kinds of marks. A bruise is a type of hematoma, which is a collection of blood. Small marks under 3 millimetres are called petechia. Marks between 3 and 10 millimetres are called purpura. If a mark is 1 centimetre or larger, it is called an ecchymosis.

severebruise
severebruise

Some ecchymoses are far away from where the injury actually happened. For example, "raccoon eyes" can happen from a skull fracture. These different names help doctors understand how the bleeding started.

Bruises can look many different colors as they change. At first, they might look red, blue, or almost black. This depends on if broken venules or arterioles caused the leak.

Black Eye 01
Black Eye 01

The colors change because your body breaks down hemoglobin. Hemoglobin produces a red-blue color. When it breaks down into biliverdin, the bruise looks green. Then it turns into bilirubin, which looks yellow. Finally, it becomes hemosiderin, which looks golden-brown.

Blaues und rotes Auge nach Fußtritt ins Gesicht (Ausschnitt)
Blaues und rotes Auge nach Fußtritt ins Gesicht (Ausschnitt)

Most light bruises heal in about two weeks.

Many things can change how a bruise looks or feels. For example, females may bruise more because they have more subcutaneous fat. Elderly people often bruise easily because their skin is thinner. Even your genes can matter, as natural redheads may bruise more easily.

Sprained foot
Sprained foot

Sometimes, bruises can be very serious and need a doctor. A harm score can be used to measure this danger from 0 to 5. A score of 5 means a critical bruise that could lead to death. Serious bruises might lead to things like compartment syndrome or even a brain injury.

Black Eye 01
Black Eye 01
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File:Blåmärken.jpg
Blåmärken.jpg
File:severebruise.jpg
severebruise.jpg
File:Sprained foot.jpg
Sprained foot.jpg
File:Blaues und rotes Auge nach Fußtritt ins Gesicht (Ausschnitt).jpg
Blaues und rotes Auge nach Fußtritt ins...
File:US Army Vet Injury.JPG
US Army Vet Injury.JPG
File:Black Eye 01.jpg
Black Eye 01.jpg
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