What do you call a mass that breaks off and causes occlusion of an artery?

The correct answer is embolism. An embolism refers to a mass—such as a blood clot, air bubble, or fat globule—that detaches from its original site and travels through the bloodstream. When this mass lodges in a blood vessel and blocks the flow of blood, it can cause an occlusion in an artery. This interruption in blood supply can potentially lead to serious conditions such as a heart attack or stroke, depending on where the occlusion occurs.

In contrast, ischemia refers to a reduced blood flow to a tissue, which may occur due to various reasons, including embolism but does not specifically imply the presence of a mass blocking the vessel. Hypoxia involves a deficiency of oxygen in the tissues, which can arise from ischemia or other factors but is not specific to the occlusion caused by a mass. Dyscrasia refers to an abnormal or pathological condition of the blood, such as blood disorders, but does not pertain to the concept of a mass causing obstruction in the arteries.