Blushing

Blushing

Blushing is a general term applied to a temporary erythema (redness) of the skin, especially the upper thorax, neck, and facial areas. The discoloration results from a brief infusion of blood following a rapid dilation of blood vessels in the affected area.

Erythema may occur as a result of infection, inflammation, or trauma to the skin. Erythema associated with blushing usually has an initiating emotional stimulus. Often blushing is a characteristic response to a set of environmental circumstances. Although the emotional key that triggers the blushing response (e.g., embarrassment at public speaking, flattering comments, etc.) may vary from individual to individual, the physiological alterations in skin circulation remain essentially the same. In all forms of blushing, there is an increase in the diameter of the capillaries (the smallest diameter blood vessels that bridge the arterial and venous system and that are the sites of vascular exchange) underlying the affected skin area.

The flow of blood in the integumentary system (skin) is generally regulated by a number of neural and humoral mechanisms. Normally the blood flow through integumentary cutaneous tissue represents less than five percent of the total circulatory flow. With blushing and other infiltrations of cutaneous tissue, the portion of blood dedicated to cutaneous tissue may increase ten to twenty times the normal levels.

As part of the sympathetic response to stress, although visceral arterioles may constrict for a brief time, cutaneous vessels may dilate and cause blushing. Sympathetic pathways to integumentary glands cause the release of bradykinin (one of several peptides that act to regulate blood vessels and smooth muscle) that dilates the skin after compression. Vasodilators such as bradykinin expand capillary diameters and allow the lumen of the capillaries to become infused and engorged with blood.

Blushing also results in a localized elevation of temperature in the infused skin tissue. This reddening is often noticed on cold days as the skin of the usually exposed face and neck attempts to counter external cold temperature by increasing blood flow to the capillaries in the face and neck. A number of sensory receptors, including thermoreceptors, especially those found in the hypothalamus and spinal cord, regulate the dilation of arterioles in cutaneous tissue. These receptors provide a vital adaptation mechanism to allow the skin to respond to extremes of external heat and cold.

In contrast to the physiology of blushing, vasoconstrictor biochemicals force capillary vessels to contract and produce a pale skin tone in the overlying skin.