The pleural cavity is a closed space in the human body that is located between the lungs and the chest wall. Under normal physiological conditions, the intrapleural pressure is lower than the atmospheric pressure, that is, the pleural cavity is in a negative pressure state. So, why is the pleural cavity negative pressure?
First, we need to understand what the pleural space is. The pleural cavity is a closed space consisting of two layers of pleura, in which the inner layer is the visceral layer pleura, which covers the surface of the lungs;The outer layer is the parietal pleura, which covers the inner surface of the chest wall. These two pleural layers are closely connected to form a closed cavity.
Second, we need to understand how pressure in the pleural space is generated. The pressure of the air between the lungs and the chest wall is unbalanced because the lung is an elastic tissue that is able to expand and contract. When the lungs expand, the pressure of the gas inside the lungs increases;When the lungs contract, the pressure of the gases inside the lungs decreases. The chest wall, on the other hand, is a rigid structure, and its gas pressure remains basically the same. Thus, when the lungs expand, the pressure of the gas in the lungs is higher than that of the chest wall, allowing the gas to flow from the lungs to the chest wall;When the lungs contract, the pressure of the gas in the lungs is lower than the pressure of the chest wall, allowing the gas to flow from the chest wall to the lungs. As a result of this gas flow, the pressure in the pleural cavity is always lower than atmospheric pressure, resulting in a negative pressure state.
So, why is the pleural cavity in a state of negative pressure?First, a negative pressure state helps maintain normal breathing movements. In a negative pressure state, the chest cavity expands when inhaled, and air enters the lungs more easily;When you exhale, your ribcage shrinks and air is more easily expelled from your body. Secondly, the negative pressure state helps to maintain normal blood circulation. In a state of negative pressure, it is easier for the heart to pump blood into the lungs for gas exchange;At the same time, it is easier for blood to flow back from the lungs to the heart. In addition, negative pressure helps maintain normal alveolar function. In a state of negative pressure, the alveoli are better able to expand and contract, which helps in the exchange of gases.
In summary, the pleural cavity is a state of negative pressure due to an imbalance in the air pressure between the lungs and the chest wall. This negative pressure state is important for maintaining normal respiratory movements, blood circulation, and alveolar function. December Creation Incentive Program