Root effect

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The Root effect is one of the factors that influence the O 2 binding of the blood. It is viewed as a special case of the Bohr effect . The effect occurs in fish , crustaceans and cephalopods . The human hemoglobin has no root effect. It is named after the first person who wrote it, R. W. Root (1931).

The effect results in a reduction in the O 2 uptake capacity. This is caused by a lowering of the pH value or by an increased CO 2 content of the blood. A down-shift can be seen in the binding curve. In addition to reducing the oxygen affinity of the hemoglobin, the protons also reduce the O 2 capacity of the hemoglobin.

The need for the Root effect is to create or maintain a high partial pressure of oxygen . This is particularly important in tissues whose function is dependent on a high oxygen supply (e.g. the retina of fish). Complete saturation of the hemoglobin with oxygen can therefore never be achieved, since only some of the attachment points are oxygenated even with a high partial pressure of the oxygen. In other words, the acidification of the blood leads to the loosening of the bond between oxygen and hemoglobin. This results in an increase in the concentration of physically dissolved O 2 and thus also in an increase in the oxygen partial pressure. This ultimately promotes diffusion from the blood into the surrounding tissue .


  • Roger Eckert, Raimund Apfelbach (Hrsg.): Tierphysiologie . 4. through Georg Thieme Verlag, Stuttgart / New York, 2002
  • Wolfgang Waser: The oxygen supply of the retina in bony fish: Development of methodical approaches in the rainbow trout, Oncorhynchus mykiss (whale tree) . Humboldt University of Berlin, 2001 (dissertation)
  • Institute for Biology II, RWTH Aachen: Lecture notes for general zoology

Individual evidence

  1. RW Root: The respiratory function of the blood of marine fishes . In: Biol. Bull. , 61, 1931, pp. 427-456.