Which of the following statements about vascular permeability in edema is true?

The statement that increased permeability allows more fluid to exit the vascular system is true in the context of edema and inflammation. During inflammatory processes, various mediators such as histamines, prostaglandins, and cytokines are released, which lead to an increase in vascular permeability. This enhanced permeability allows proteins and fluid to leak out of the capillaries and into the interstitial spaces, causing swelling and contributing to the formation of edema. This is a crucial aspect of the inflammatory response, as it facilitates the delivery of immune cells and antibodies to the affected tissues.

In contrast, other statements are not aligned with the physiological understanding of vascular permeability. For instance, the assertion that it decreases during inflammation is incorrect because inflammation typically results in increased permeability. The notion that it is caused solely by decreased sodium levels oversimplifies the complex mechanisms involved in edema, which can include inflammatory mediators, alterations in hydrostatic pressures, and osmotic gradients. Lastly, the idea that vascular permeability is unrelated to tissue swelling contradicts the established connection between increased permeability and the accumulation of fluid in tissues, which directly leads to edema.