Ans. When the skin is stroked more firmly with a pointed instrument, there is reddening at the site (red reaction), then swelling (wheal) and diffuse, mottled reddening around the injury. This redness spreading out from injury (flare).
The initial redness is due to capillary dilation.
The swelling is due to increased capillaries and post capillary venules.
The redness spreading (flare) is due to arteriolar dilation.
This three part response, the red reaction, wheal, flare is called triple response.
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