pleural space
Summary
The pleural space is a potential space between the visceral and parietal pleura containing a thin layer of pleural fluid (~10-15 mL) that lubricates pleural surfaces and maintains negative pressure for lung expansion. Pathological accumulation of fluid (pleural effusion), air (pneumothorax), or blood (hemothorax) in this space can compromise respiratory function.
Detail
The pleural space is bounded by two layers of pleura: the visceral pleura (covering the lung surface) and the parietal pleura (lining the chest wall, diaphragm, and mediastinum). Under normal conditions, this space contains approximately 10-15 mL of pleural fluid produced by the parietal pleura and absorbed by both pleural surfaces. The pleural fluid serves as a lubricant allowing smooth movement during respiration and creates surface tension that helps keep the lungs inflated. The pleural space maintains a negative pressure (subatmospheric) that is essential for lung expansion during inspiration. Starling forces govern fluid dynamics: hydrostatic pressure favors fluid formation while oncotic pressure and lymphatic drainage promote reabsorption. Pathological conditions include pleural effusion (excess fluid from increased production or decreased absorption), pneumothorax (air accumulation leading to lung collapse), hemothorax (blood accumulation), and empyema (infected pleural fluid). Clinical significance includes the need for thoracentesis for diagnostic or therapeutic purposes and understanding of chest tube placement principles.
Sources
- First Aid for the USMLE Step 1
- Robbins Basic Pathology
- Harrison's Principles of Internal Medicine
- West's Respiratory Physiology
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