MCQ – 87710

A 7-year-old boy punctures his thumb with a rusty nail. Four hours later, the thumb appears red and swollen. Initial swelling of the boy’s thumb is primarily due to which of the following mechanisms?

Correct Answer � C Explanation

Answer :C Increased capillary permeability

Forces that regulate the balance of vascular and tissue fluids include

(1)hydrostatic pressure

(2) oncotic pressure

(3) osmotic pressure,

(4) lymph flow. 

• During inflammation, an increase in the permeability of the endothelial cell barrier results in local edema.

• Vasodilation of arterioles exacerbates fluid leakage, and vasoconstriction of postcapillary venules increases the hydrostatic pressure in the capillary bed  potentiating the formation of edema.

•  Vasodilation of venules decreases capillary hydrostatic pressure and inhibits the movement of fluid into the extravascular spaces.

•  Acute inflammation is not associated with changes in plasma oncotic pressure