Thursday, August 5, 2010

Types of Circulatory System

Blushing is the reddening of the skin of the face, the word is often used when the redness corresponds to an emotional response to certain anxiety-producing emotions like shame, guilt, anxiety, nervousness or modesty. The blush can also be associated with states of infatuation.

If the redness continues for a prolonged period after having blushed, then it may relate to symptoms suggestive of rosacea.

There is a medical condition called idiopathic craniofacial erythema, in which someone blushes with great intensity against a very small stimulus. It is associated with a strong phobia of social interaction.

Eritrofobia (literally "fear of redness") refers to the flush of pathological nature.

Eritrosis (from "red cell" and "-osis") f. Exaggerated tendency to blush.

Cuperosis is the dilation of blood vessels that supply the dermis in the form of branches or spider web.

Telangiectasia is the dilation of the veins near the surface of the skin that look like spider.

Anatomy physiological blood flow in human skin

Blood flow on the skin has the function to carry nutrients to the skin and regulate body temperature. The higher skin blood flow, the greater the amount of heat that radiates. The restriction of blood flow on the skin reduces heat loss from the body, which is an important element in a cold environment.

The circulatory system of the skin contains three major types of channels through which blood flows that allow fulfilling the two tasks mentioned previously.

The first type are arteries, capillaries and veins that serve mainly the function of providing nutrients. The second type is the subcutaneous venous plexus that plays an important role in heat conduction, and contains a significant fraction of the skin blood volume.

The third type consists of sets of arteriovenous anastomoses found in those parts of the body especially exposed to conditions of maximum cooling like the hands, feet, nose, lips and ears. These areas are called apical structures and have a high irrigation.

The bodies anastomoses connect arterioles and venules skin directly, to play an important role in reducing blood flow in cold environments (Rowell. 1993, Guyton. 1981; Rowell. 1974).

Regulation of skin blood flow

The blood flow in cutaneous resistance vessels and subcutaneous venous plexus are regulated both at neuronal and local levels. However, there are some important differences between them.

One is that cutaneous resistance vessels exhibit a basal tone independently of innervation in reaction to passive stretch Porla induced blood pressure (Rowell. 1974). Usually this intrinsic basal tone is not present in skin capacitance vessels.


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