What is sputum?

Sputum refers to the mucous secretion that is produced by the lungs and is expelled from the mouth, particularly during a cough. It consists of a combination of mucus, which helps to trap pathogens and particles in the respiratory system, along with any cellular debris that may be present. The presence and characteristics of sputum can provide important diagnostic information about a person's respiratory health, such as whether an infection is present, the type of infection, or the state of the lungs.

The other options do not accurately define sputum. While it is a type of bodily fluid, the term specifically relates to the mucous secretion from the lungs, which is not captured simply by calling it a bodily fluid. A form of medication does not apply here, as sputum is not a treatment but rather a byproduct of the respiratory process. Additionally, while sputum can be a symptom related to infection, it is not itself a symptom; rather, it is the actual substance that may indicate a respiratory issue when analyzed.