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Hyperaemia

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Hyperaemia

Hyperaemia
Classification and external resources
ICD-9-CM 780.99
DiseasesDB 4466
MeSH D006940

Hyperaemia or hyperemia is the increase of blood flow to different tissues in the body. It can have medical implications, but is also a regulatory response, allowing change in blood supply to different tissues through

  • Active and reactive hyperemia. Richard E. Klabunde, Ph.D. Cardiovascular Physiology Concepts. Accessed on 27 February 2006.

External links

  1. ^ Jon Aster, Vinay Kumar, Abul K. Abbas; Nelson Fausto (2009). Robbins & Cotran Pathologic Basis of Disease (8th ed.). Philadelphia: Saunders. p. 113.  

References

Reactive hyperaemia often occurs as a consequence of Raynaud's phenomenon, where the vasospasm in the vasculature leads to ischaemia and necrosis of tissue and thus a subsequent increase in blood flow to remove the waste products and clear up cell debris.

This is commonly tested in the legs using Buerger's test.

Reactive hyperaemia is the transient increase in organ blood flow that occurs following a brief period of ischaemia. Following ischaemia there will be a shortage of oxygen and a build-up of metabolic waste.

Reactive hyperaemia

Some tissues require oxygen and fuel more quickly or in greater quantities. Examples of tissues and organs that are known to have specialized mechanisms for functional hyperaemia include:

Since most of the common nutrients in the body are converted to carbon dioxide when they are metabolized, smooth muscle around blood vessels relax in response to increased concentrations of carbon dioxide within the blood and surrounding interstitial fluid. The relaxation of this smooth muscle results in vascular dilation and increased blood flow.

Conversely, when a tissue is less metabolically active, it produces fewer metabolites which are simply washed away in blood flow.

When cells within the body are active in one way or another, they use more oxygen and fuel, such as glucose or fatty acids, than when they are not. Increased metabolic processes create more metabolic waste. The byproducts of metabolism are vasodilators. (Vasodilating metabolites: CO2, H+, K+, lactate, adenosine) Local arterioles respond to metabolism by dilatating, allowing more blood to reach the tissue. This prevents deprivation of the tissue.

Functional hyperaemia, metabolic hyperemia or active hyperaemia, is the increased blood flow that occurs when tissue is active.

Functional hyperaemia

Functional hyperaemia is an increase in blood flow to a tissue due to the presence of metabolites and a change in general conditions. When a tissue increases activity there is a well-characterized fall in the partial pressure of oxygen and pH, an increase in partial pressure of carbon dioxide, and a rise in temperature and the concentration of potassium ions. The mechanism for vasodilation is unclear, but it may have something to do with the opening of precapillary sphincter.

Hyperaemia and the regulation of blood flow

Contents

  • Hyperaemia and the regulation of blood flow 1
  • Functional hyperaemia 2
  • Reactive hyperaemia 3
  • References 4
  • External links 5

Hyperaemia can also occur due to a fall in atmospheric pressure outside the body. [1]

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