Final answer:
The potential sources of an embolus causing an obstruction in the brain include a thrombus in the heart and an air bubble from intravenous injection. Kidney stones cannot travel to the brain, hence they're not a source. Normal blood cells can cause embolisms only if they are part of a blood clot.
Step-by-step explanation:
The sources of an embolus causing an obstruction in the brain can be diverse, and among the options given, a thrombus in the heart, an air bubble from an intravenous injection, and normal blood cells—if part of a blood clot can be potential sources. A thrombus in the heart can break off, especially in conditions like arrhythmia, and travel to the brain to cause an ischemic stroke. Blood clot fragments or an air bubble from an intravenous line can also travel to the brain and lodge in a vessel, disrupting normal blood flow. However, a kidney stone is not capable of traveling to the brain and is therefore not a potential source of a cerebral embolus. Normal blood cells, unless they form a clot, generally do not cause embolisms on their own.
When an embolism occurs in the brain, it can lead to a loss of specific functions depending on the area affected. These medical emergencies require urgent treatment to remove or diminish the blockage and restore normal blood flow to minimize damage to brain tissue. Almost 90 percent of strokes that are caused by emboli are ischemic strokes, which occur due to loss of blood flow because an artery is blocked, often by an embolus.