Permeability increases in blood vessels during which phase of injury?

Permeability increases in blood vessels during which phase of injury?

• A. Permeability changes
• B. Metabolic changes
• C. Leukocyte migration
• D. Ultrastructural changes

Answer: (A)

The key idea is that the early vascular response to injury drives increased permeability. When tissue is injured, inflammatory mediators such as histamine cause the endothelial cells lining the blood vessels to contract and form gaps. These gaps make the vessel walls more permeable, allowing fluid and proteins to leak into the surrounding tissue. This vascular phase creates the edema and sets the stage for the next steps, where leukocytes migrate out of the vessels into the tissue during the cellular phase. So the phase characterized by increased permeability is the vascular (permeability) changes that occur early after injury.

The key idea is that the early vascular response to injury drives increased permeability. When tissue is injured, inflammatory mediators such as histamine cause the endothelial cells lining the blood vessels to contract and form gaps. These gaps make the vessel walls more permeable, allowing fluid and proteins to leak into the surrounding tissue. This vascular phase creates the edema and sets the stage for the next steps, where leukocytes migrate out of the vessels into the tissue during the cellular phase. So the phase characterized by increased permeability is the vascular (permeability) changes that occur early after injury.