Blood clots are the clumps that occur when the blood hardens from a liquid to a solid (coagulates). A blood clot that forms inside a blood vessel or within the heart and remains there is called a thrombus. A thrombus that travels from the blood vessel or heart to another location in the body is called an embolus. For example, an embolus that occurs in the lungs is called a pulmonary embolism.
Sometimes other materials can act like an embolus and block blood flow including air, clumps of fat or atherosclerotic plaques, or metastatic tumor tissue.




