Haemostasis is the human body's response to blood vessel injury and bleeding. It involves a coordinated effort between platelets and numerous blood clotting proteins (or factors), resulting in the formation of a blood clot and subsequent stopping of the bleed.
Tissue factor is a protein that is exposed to blood once a blood vessel is injured (causing bleeding). The process of haemostasis starts when the exposed tissue factor binds to a certain coagulation protein called factor seven (FVII) which circulates within the blood stream. This causes the subsequent activation of FVII to FVIIa. The binding of tissue factor and FVIIa is only the first step in a process that will in the end lead to the development of a strong, stable blood clot that will stop and prevent further bleeding.
Generally in healthy people without bleeding disorders, control of bleeding is achieved very quickly and without the need for medical treatment. In major trauma or surgery, doctors often need to help patients to reach normal haemostasis in order to minimise blood loss and further injury.
However, some people are born with a bleeding disorder (congenital) so that haemostasis does not work properly. Most of these bleeding disorders are hereditary passed on from parents or run in families. An example of this is haemophilia.
Sometimes people who have never experienced any bleeding problems themselves or in their families, can develop a condition that causes them to bleed, known as acquired haemophilia. In this disorder, even minor cuts and bruises can require medical treatment.
HQMMA/N7/0914/0067. November 2014.