Final answer:
Thrombosis is the formation of a blood clot attached to the wall of a blood vessel or the heart, which can obstruct blood flow and become dangerous if a piece breaks away, leading to an embolism.
Step-by-step explanation:
The formation of a blood clot attached to the wall of the heart or blood vessel is called thrombosis. A blood clot, known as a thrombus, is an aggregation of blood components such as platelets, red blood cells, and sometimes white blood cells, which are typically trapped within a mass of fibrin strands.
While clots are essential in stopping bleeding when a blood vessel is damaged, in thrombosis, clots form even when there is minimal or no vessel damage, potentially blocking blood flow and leading to conditions like pulmonary embolism or atherosclerosis. Factors such as venous stasis or conditions like thrombocytosis and thrombophilia can increase the risk of thrombosis. If part of a thrombus breaks loose, it becomes an embolus, which can travel and block blood vessels farther away, causing life-threatening conditions like heart attacks, strokes, or pulmonary embolisms.