Root effect
Encyclopedia
The Root Effect is a physiological phenomenon that occurs in fish
hemoglobin
, named after its discoverer R. W. Root. It is the phenomenon where an increased proton
or carbon dioxide
concentration (lower pH
) lowers hemoglobin's affinity and carrying capacity for oxygen
. The Root effect is to be distinguished from the Bohr effect
where only the affinity to oxygen is reduced. Hemoglobins showing the root effect show a loss of cooperativity at low pH. This results in the Hb-O2 dissociation curve
being shifted downward and not just to the right. At low pH, hemoglobins showing the root effect don't become fully oxygenated even at oxygen tensions up to 20kPa.This effect allows hemoglobin in fish with swim bladders to unload oxygen into the swim bladder against a high oxygen gradient. The effect is also noted in the choroid rete
, the network of blood vessel
s which carries oxygen to the retina
. In the absence of the Root effect, retia
will result in the diffusion of some oxygen directly from the arterial blood to the venous blood, making such systems less effective for the concentration of oxygen.
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...
, named after its discoverer R. W. Root. It is the phenomenon where an increased proton
Proton
The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
or carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
concentration (lower pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
) lowers hemoglobin's affinity and carrying capacity for oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
. The Root effect is to be distinguished from the Bohr effect
Bohr effect
Bohr effect is a property of hemoglobin first described in 1904 by the Danish physiologist Christian Bohr , which states that an increasing concentration of protons and/or carbon dioxide will reduce the oxygen affinity of hemoglobin...
where only the affinity to oxygen is reduced. Hemoglobins showing the root effect show a loss of cooperativity at low pH. This results in the Hb-O2 dissociation curve
Oxygen-haemoglobin dissociation curve
The oxygen–haemoglobin dissociation curve plots the proportion of haemoglobin in its saturated form on the vertical axis against the prevailing oxygen tension on the horizontal axis. The oxyhaemoglobin dissociation curve is an important tool for understanding how our blood carries and releases...
being shifted downward and not just to the right. At low pH, hemoglobins showing the root effect don't become fully oxygenated even at oxygen tensions up to 20kPa.This effect allows hemoglobin in fish with swim bladders to unload oxygen into the swim bladder against a high oxygen gradient. The effect is also noted in the choroid rete
Rete
Rete may refer to: An interwoven network of nerves, blood vessels or passageways.-Italy:*Net , in Latin*La Rete , the common name given to Movimento per la Democrazia , an Italian political party-Technology:...
, the network of blood vessel
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...
s which carries oxygen to the retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
. In the absence of the Root effect, retia
Rete mirabile
A rete mirabile is a complex of arteries and veins lying very close to each other, found in some vertebrates. The rete mirabile utilizes countercurrent blood flow within the net...
will result in the diffusion of some oxygen directly from the arterial blood to the venous blood, making such systems less effective for the concentration of oxygen.