When skin is blanched, it takes on a whitish appearance as
blood flow
Hemodynamics or haemodynamics are the dynamics of blood flow. The circulatory system is controlled by homeostatic mechanisms of autoregulation, just as hydraulic circuits are controlled by control systems. The hemodynamic response continuously ...
to the region is prevented. This occurs during and is the basis of the physiologic test known as
diascopy
Diascopy is a test for blanchability performed by applying pressure with a finger or glass slide and observing color changes.Marks, James G; Miller, Jeffery (2006). ''Lookingbill and Marks' Principles of Dermatology'' (4th ed.). Elsevier Inc. Page ...
.
Blanching of the fingers is also one of the most clinically evident signs of
Raynaud's phenomenon.
Blanching is prevented in
gangrene as the red blood corpuscles are extravasated and impart red color to the gangrenous part.
See also
*
Diascopy
Diascopy is a test for blanchability performed by applying pressure with a finger or glass slide and observing color changes.Marks, James G; Miller, Jeffery (2006). ''Lookingbill and Marks' Principles of Dermatology'' (4th ed.). Elsevier Inc. Page ...
*
Pallor
References
Dermatologic terminology
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