In acute inflammation, excessive fluid seepage occurs due to increased permeability of?
**Core Concept**
The increased permeability of blood vessels in acute inflammation is primarily due to the disruption of the endothelial cell junctions, allowing fluid and white blood cells to leak into the interstitial space. This process is mediated by various inflammatory mediators, including histamine, bradykinin, and cytokines.
**Why the Correct Answer is Right**
The increased permeability is primarily due to the contraction of endothelial cells and the widening of intercellular gaps, which is caused by the action of histamine on H1 receptors. Histamine is released from mast cells in response to tissue injury or infection, and it binds to H1 receptors on endothelial cells, leading to the contraction of actin filaments and the opening of gap junctions between endothelial cells. This allows fluid and white blood cells to leak into the interstitial space, leading to edema and increased vascular permeability.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct cellular component responsible for increased permeability in acute inflammation.
**Option B:** This option is incorrect because it refers to the process of phagocytosis, which is a different mechanism of cellular response to inflammation.
**Option C:** This option is incorrect because it refers to the process of coagulation, which is a separate mechanism of response to tissue injury.
**Clinical Pearl / High-Yield Fact**
In acute inflammation, the increased vascular permeability is a critical step in the recruitment of white blood cells to the site of injury or infection, and it is mediated by the action of histamine on H1 receptors on endothelial cells.
**Correct Answer: C. Endothelial cells. Endothelial cells.**