Hyperemia describes 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
vasodilationVasodilation refers to the widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large arteries, smaller arterioles and large veins. The process is essentially the opposite of vasoconstriction, or the narrowing of blood vessels. When...
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Functional hyperemiaFunctional hyperemia, or active hyperemia, is the increased blood flow that occurs when tissue is active.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. The blood vessels compensate for this...
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.
Hyperemia describes 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
vasodilationVasodilation refers to the widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large arteries, smaller arterioles and large veins. The process is essentially the opposite of vasoconstriction, or the narrowing of blood vessels. When...
.
Hyperemia and the regulation of blood flow
Functional hyperemiaFunctional hyperemia, or active hyperemia, is the increased blood flow that occurs when tissue is active.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. The blood vessels compensate for this...
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 sphinctersThe precapillary sphincter is a band of smooth muscle that adjusts the blood flow into each capillary. Blood flow in a capillary changes as vasomotion occurs. The entire capillary bed may be bypassed by blood flow through arteriovenous anastomoses. A precapillary sphincter encircles each...
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Active hyperemia is a term used to describe dilation of arteriolar
smooth muscleSmooth muscle is an involuntary non-striated muscle, found within the tunica media layer of large and small arteries and veins, the bladder, uterus, male and female reproductive tracts, gastrointestinal tract, respiratory tract, arrector pili of skin, the ciliary muscle, and iris of...
to increase blood flow in response to an increase in
metabolismMetabolism is the set of chemical reactions that occur in living organisms to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down organic matter,...
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Reactive hyperemiaReactive hyperemia is the transient increase in organ blood flow that occurs following a brief period of ischemia . Following Ischemia there will be a shortage of oxygen and a build-up of metabolic waste....
is a profound increase in blood flow to an organ after being
occludedOcclusion is a term indicating that the state of something, which is normally open, is now totally closed.* In cardiology, the term is often used to refer to blood vessels, arteries or veins which have become totally blocked to any blood flow...
due to a shortage of oxygen and a build-up of metabolic waste.
External links
- Active and reactive hyperemia. Richard E. Klabunde, Ph.D. Cardiovascular Physiology Concepts. Accessed on 27 February 2006.