Pleural cavities

Definition

Pleural cavities are the two thin, fluid-filled spaces between the layers of pleura surrounding each lung. These cavities play a critical role in respiration by allowing the lungs to expand and contract smoothly during breathing while also providing a protective layer against friction between the lungs and the chest wall.

5 Must Know Facts For Your Next Test

1. Each pleural cavity contains a small amount of pleural fluid, which reduces friction during breathing movements.
2. The negative pressure in the pleural cavities is essential for lung inflation, as it helps to pull the lungs outward when the thoracic cavity expands.
3. Pleural effusion is a condition where excess fluid accumulates in the pleural cavities, which can impair breathing and cause discomfort.
4. The pleural cavities provide a compartmentalized space that helps prevent the spread of infection between the lungs and other thoracic organs.
5. During inhalation, the diaphragm contracts and moves downward, causing an increase in intrathoracic volume, which aids in drawing air into the lungs through the pleural cavities.

Review Questions

• Explain how pleural cavities contribute to effective respiration and what would happen if they were compromised.
  • Pleural cavities contribute to effective respiration by maintaining negative pressure, which allows for lung expansion during inhalation. If these cavities were compromised, such as by a pneumothorax where air enters the pleural space, this negative pressure could be lost, leading to lung collapse and difficulty in breathing. The smooth movement provided by pleural fluid would also be disrupted, causing pain and friction with each breath.
• Discuss how changes in intrapleural pressure affect lung function during different phases of breathing.
  • Changes in intrapleural pressure directly influence lung function by affecting airflow during inhalation and exhalation. During inhalation, intrapleural pressure decreases as the thoracic cavity expands, creating a vacuum that draws air into the lungs. Conversely, during exhalation, intrapleural pressure increases as the thoracic cavity contracts, forcing air out of the lungs. Any alterations in this pressure can significantly impact respiratory efficiency.
• Evaluate the clinical significance of understanding pleural cavities in diagnosing respiratory conditions such as pleural effusion and pneumothorax.
  • Understanding pleural cavities is clinically significant as it aids in diagnosing various respiratory conditions. For instance, identifying pleural effusion involves recognizing fluid accumulation within these cavities through imaging techniques like ultrasound or chest X-ray. Similarly, diagnosing pneumothorax requires an understanding of how air can enter the pleural space and disrupt normal lung function. Both conditions can lead to significant complications if not addressed promptly, making this knowledge vital for effective patient management.

Related terms

Pleura:

The double-layered membrane that encloses each lung, consisting of the visceral pleura covering the lung surface and the parietal pleura lining the thoracic cavity.

Thoracic cavity: The chamber of the body that houses the lungs and heart, protected by the rib cage and separated from the abdominal cavity by the diaphragm.

Intrapleural pressure: The pressure within the pleural cavity, which is typically lower than atmospheric pressure and plays an important role in keeping the lungs inflated.