ANATOMY

Detailed explanation-1: -The mediastinal and diaphragmatic pleurae cover the mediastinum and diaphragm, respectively. During quiet respiration, the visceral and parietal pleura separate in regions that are not occupied by the lungs, resulting in pleural recesses. These allow for expansion during forced respiration.

Detailed explanation-2: -A thin layer of tissue that covers the lungs and lines the interior wall of the chest cavity. It protects and cushions the lungs. This tissue secretes a small amount of fluid that acts as a lubricant, allowing the lungs to move smoothly in the chest cavity while breathing.

Detailed explanation-3: -The pleura is a vital part of the respiratory tract. Its role is to cushion the lung and reduce any friction that may develop between the lung, rib cage, and chest cavity.

Detailed explanation-4: -Pleural fluid functions by lubricating the space between the pleura, allowing the pleura to glide smoothly during inhalation and exhalation. In this way, it cushions delicate lung tissues against friction from the ribs and the chest wall itself.

Detailed explanation-5: -The pressure of the pleural fluid is subatmospheric and maintains the negative pressure between the lungs and thoracic cavity, which is necessary for inhalation while also preventing the lungs from collapsing.