What leads to the "leakiness" and swelling in injured tissue?

• A. Increased blood flow due to vasodilation
• B. Loss of cell membrane integrity in injured cells
• C. Release of histamine from mast cells
• D. Vasoconstriction of capillaries in the area

Answer: (B)

The phenomenon of "leakiness" and swelling in injured tissue is fundamentally related to the release of various chemical mediators during the inflammatory response. One of the most significant contributors to this process is the release of histamine from mast cells. Histamine is a potent vasodilator and increases vascular permeability, leading to an influx of fluid and plasma proteins into the interstitial space. This increased permeability results in the classic signs of inflammation, including swelling and redness in the affected area.

While loss of cell membrane integrity is critical in the cellular response to injury, it primarily affects the affected cells themselves rather than directly causing the generalized "leakiness" and swelling seen in the surrounding tissue. Inflammation initiated by histamine release plays a primary role in the overall response, particularly through changes in blood vessel dynamics and permeability. Increased blood flow due to vasodilation also contributes to redness and warmth but is not the sole factor in the swelling characterized as "leakiness." Vasoconstriction typically occurs initially in response to tissue injury to control bleeding and is not consistent with the conditions causing swelling.

Thus, the release of histamine highlights its essential contribution to increased vascular permeability, leading to the characteristic "leakiness" and swelling in the context of inflammation