Final Answer:
d) Tumor , while a thrombus is a common cause of embolism, other substances like air bubbles, fat droplets, bone fragments, and particularly tumors can also serve as sources of emboli that may lead to blockages in the lung's blood vessels, causing significant health issues.
Explanation:
An embolus refers to any object, such as a blood clot (thrombus), that travels through the bloodstream and gets lodged in a blood vessel, causing obstruction. Apart from a thrombus, other substances like air bubbles, fat droplets, bone fragments, and tumors can also form emboli. Tumors can shed cells or small clusters into the bloodstream, which can then travel to various organs, including the lungs, leading to the formation of an embolus. When a tumor or its fragments enter the bloodstream, they can obstruct blood flow in the pulmonary vessels, causing significant complications.
These tumors that generate emboli might originate from various parts of the body and spread through metastasis or other means. Once in circulation, tumor emboli can reach the lungs and get stuck in the blood vessels, impeding blood flow and causing potential damage. This scenario can result in severe consequences, affecting lung function and potentially causing respiratory distress.
In summary, while a thrombus is a common cause of embolism, other substances like air bubbles, fat droplets, bone fragments, and particularly tumors can also serve as sources of emboli that may lead to blockages in the lung's blood vessels, causing significant health issues.