The parietal pleura is a thin membrane within the human body. This lining protects internal structures and contributes to a vital physiological process. It is important for maintaining internal conditions.
Where It Is Located and How It Is Structured
The parietal pleura lines the inner wall of the chest cavity, known as the thoracic cavity. It covers the ribs, intercostal muscles, and the top surface of the diaphragm. This membrane also lines the mediastinum, the central compartment of the chest.
This membrane is a serous membrane with a smooth, moist surface. It is composed of simple squamous epithelial cells, called mesothelium, supported by connective tissue. The parietal pleura is divided into regions: costal (lining the ribs), diaphragmatic (covering the diaphragm), mediastinal (lining the mediastinum), and cervical (extending into the neck).
Its Role in Breathing
The parietal pleura plays a direct role in breathing mechanics. Its smooth surface allows the lungs to expand and contract with minimal friction against the chest wall during respiration. This movement is important for the efficient operation of the respiratory system.
The adherence of the parietal pleura to the chest wall helps maintain a negative pressure within the pleural cavity. This negative pressure is important because it acts like a vacuum, pulling the lungs outwards to inflate as the chest cavity expands. Without this pressure, the lungs would struggle to fill. The coordinated action of the parietal pleura and the chest wall facilitates the rhythmic process of respiration.
The Pleural Space and Fluid
Between the parietal pleura and the visceral pleura, which covers the surface of the lungs, lies a narrow space known as the pleural cavity. This cavity is a potential space, meaning its layers are almost in contact. Within this space, a thin film of pleural fluid is present.
The pleural fluid serves two primary functions. First, it acts as a lubricant, allowing the parietal and visceral pleura to glide smoothly over each other during breathing, minimizing friction and preventing irritation. Second, the fluid creates surface tension, causing the two pleural layers to adhere closely. This adhesion ensures that when the chest wall expands, the lungs are pulled along, enabling effective inflation and deflation.