MCAT Question A Day - 4/22/14 - Answer!
The inflammatory response results from the release of histamine by mast cells or basophils. The redness, heat, pain, and swelling associated with inflammation are due to which physiological effects of histamine?
A. Dilation of local blood vessels / less fluid leakage from capillaries
B. Dilation of local blood vessels / more fluid leakage from capillaries
C. Constriction of local blood vessels / less fluid leakage from capillaries
D. Constriction of local blood vessels / more fluid leakage from capillaries
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The correct answer is (B). An understanding of the effects of histamine and the inflammatory response are helpful, but not essential. Logical thinking will come through here as well. The symptoms described—e.g., redness and heat—would result from more red, warm blood in the area (dilation of blood vessels). Similarly, swelling and pain would result from additional fluids in the area stimulating pain receptors (more fluid leakage from capillaries).
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