Question

One of the inflammatory reactions induced by histamine is

• A. vasoconstriction of blood vessels
• B. vasodilation of peripheral blood vessels
• C. increased vascular permeability
• D. accelerated blood clotting

Answer 1

Answer: (B)

Mast cells present in areolar tissue secrete histamine (vasodilator), serotonin (vasoconstrictor) and heparin (anticoagulant). Histamine causes dilation of capillaries and small blood vessels surrounding the injury and increases the permeability of the capillary walls. The more blood Rows to area making it red and warm. The fluid (plasma) leaks out into the tissue spaces, causing it swelling. This reaction of the body is known as inflammatory response.