What condition can excess interstitial fluid commonly impair?

• A. Blood flow to the heart
• B. Oxygen diffusion into the capillaries
• C. Ventilation-perfusion matching
• D. Carbon dioxide elimination

Answer: (B)

Excess interstitial fluid can directly impair the diffusion of oxygen into capillaries due to the increased distance and resistance it creates for gas exchange. When there is an accumulation of interstitial fluid, the surrounding tissue becomes edematous, which can hinder the movement of oxygen from the alveoli in the lungs into the bloodstream. This can lead to decreased oxygen availability for the body’s tissues, as the diffusion process relies on a relatively thin barrier for efficient gas exchange.

While other choices relate to cardiovascular or respiratory function, they do not directly pertain to the effects of interstitial fluid on oxygen diffusion. Hence, the correct choice highlights the specific physiological impact of excess interstitial fluid on oxygen transport in the bloodstream.