Saliva and sputum can be differentiated primarily by their origin, consistency, and composition. Saliva comes from the mouth, is typically thin and watery, and is primarily for lubrication and digestion. Sputum, on the other hand, originates from the lungs and lower airways, is usually thick and sticky, and often contains mucus, cells, and sometimes blood or pus.
Here's a more detailed comparison:
| Feature | Saliva | Sputum |
|---|---|---|
| Origin | Mouth (salivary glands) | Lungs, bronchi, and trachea (lower respiratory tract) |
| Consistency | Thin and watery | Thick and sticky |
| Appearance | Clear or slightly cloudy | Can be clear, white, yellow, green, brown, or blood-tinged |
| Composition | Water, enzymes, electrolytes, mucus | Mucus, cells (immune cells, epithelial cells), bacteria, viruses, and potentially blood or pus |
| Primary Function | Lubrication, digestion, oral hygiene | Clears debris from the respiratory tract |
| When Produced | Constantly, especially when eating or smelling food | Usually only produced when there is respiratory illness or irritation |
Key Differences Summarized:
- Source: Saliva is from the mouth; sputum is from the lungs.
- Texture: Saliva is thin and watery; sputum is thick and sticky.
- Reason for Production: Saliva is always present; sputum is typically a sign of illness or irritation.
Important Considerations:
If you are asked to collect sputum for a medical test (e.g., to check for tuberculosis), be very careful to avoid collecting saliva instead. The sample needs to come from deep within your lungs. If you're having trouble producing sputum, try breathing steam from a hot shower or a pan of boiling water to help loosen the mucus.
