What happens in your body when you start to bleed? When your body is injured and starts to bleed, bleeding stops when a clot forms. The process of making clots in the body is called coagulation. When a blood clot forms properly, the blood holds together firmly at the site of the injury and the bleeding stops. People who have a bleeding disorder are unable to make proper blood clots.
This section about what happens when a person bleeds covers the following:
Why is it Difficult to Stop Bleeding?
How is a Blood Clot Made?
Blood clotting, or coagulation, is the complex chemical process that controls bleeding. This process uses as many as 13 different proteins. These proteins are called blood clotting factors or coagulation factors. When your blood clots, the blood changes from a liquid to a solid at the site of an injury.
Your blood has many different components, such as red blood cells, white blood cells, platelets, and clotting factors that float through your blood vessels in a liquid called plasma. When a blood vessel is injured (for example, from a cut on your skin or an injury inside your body), blood starts to flow. The first step in controlling blood loss is for the blood vessel to narrow to lessen blood flow. Within seconds, tiny platelets rush to the area of the injury and bunch together around the wound. They attract other platelets and help form a temporary plug to close the break at the area of injury.
When a blood vessel is injured, your body has tissue factors to help stop bleeding. The tissue factors start a chemical reaction that causes clotting factors to produce fibrin. Fibrin is a strong, strand-like material that surrounds the platelet plug and keeps the plug firm and stable. Over the next several days to weeks, the clot strengthens and then dissolves as your wound heals.
Why is it Difficult to Stop Bleeding?
If you have a bleeding disorder, you are not able to build a blood clot or the blood clot you build is not stable enough. Depending on the type of the disorder, either the formation of the initial platelet plug, or the fibrin clot is affected. For von Willebrand disease (VWD) and platelet disorders the development of the platelet plug is limited. The platelets either do not stick to the blood vessel wall, do not connect to each other, or are unable to signal to other platelets to come to the injury site.
For hemophilia and ultra-rare factor deficiencies the formation of the fibrin clot is limited. Depending on the amount of the deficient factor in the bloodstream the fibrin clot might either be very thin or not developed at all. Some people with VWD also have a low amount of factor FVIII (8). In this case, both the formation of the platelet plug, and the fibrin clot will be affected.
If you want more information about clotting please go to the Clotting Cascade video series.
What happens when a person has a bleeding disorder
No bleeding disorder
Bleeding starts
Vessels constrict
Platelet plug
Fibrin clot
bleeding disorder
Bleeding starts
Vessels constrict
Incomplete platelet plug; continued bleeding