Explain how the changes in alveolar structure cause a decrease blood oxygen levels emphysema?

In emphysema, the alveolar walls are destroyed, leading to the formation of large air sacs that replace the normal細かい構造. This has several effects that contribute to a decrease in blood oxygen levels:

Reduced surface area for gas exchange: The destruction of alveolar walls reduces the total surface area available for gas exchange. This means that less oxygen can be taken up into the bloodstream from the air in the lungs.

Increased diffusion distance: The distance that oxygen must travel to reach the capillaries in the alveolar walls is increased in emphysema. This makes it more difficult for oxygen to diffuse across the alveolar-capillary membrane and enter the bloodstream.

Loss of elastic recoil: The elastic recoil of the lungs is provided by the elastin fibers in the alveolar walls. In emphysema, these fibers are destroyed, leading to a loss of elastic recoil. This makes it more difficult for the lungs to expand and recoil during breathing.

Air trapping: The destruction of alveolar walls and loss of elastic recoil lead to air trapping in the lungs. This means that some of the air that is breathed in remains in the lungs and is not expelled during exhalation. This further reduces the amount of oxygen that can be taken up into the bloodstream.

Ventilation-perfusion mismatch: The destruction of alveolar walls and loss of elastic recoil also lead to a ventilation-perfusion mismatch. This means that some areas of the lungs are receiving more air than blood flow, while other areas are receiving more blood flow than air. This results in a decrease in the efficiency of gas exchange.

All of these factors contribute to a decrease in blood oxygen levels in emphysema. This can lead to a variety of symptoms, including shortness of breath, fatigue, and confusion. In severe cases, emphysema can be fatal.