Definition of hemoglobin
1 : an iron-containing respiratory pigment of vertebrate red blood cells that consists of a globin composed of four subunits each of which is linked to a heme molecule, that functions in oxygen transport to the tissues after conversion to oxygenated form in the gills or lungs, and that assists in carbon dioxide transport back to the gills or lungs after surrender of its oxygen
2 : any of numerous iron-containing respiratory pigments of various organisms (such as invertebrates and yeasts)
Did You Know?
When filled with oxygen, the hemoglobin in your blood is bright red; returning to the lungs without its oxygen, it loses its brightness and becomes somewhat bluish. Hemoglobin levels can change from day to day, and may be affected by such factors as a lack of iron in the diet, a recent loss of blood, and being pregnant. When you give blood, a nurse first pricks your finger to test your hemoglobin level; a low hemoglobin count indicates anemia and may mean that you shouldn't give blood that day. Mild anemia is generally of little importance, but some types can be very serious.
Origin and Etymology of hemoglobin
International Scientific Vocabulary, short for earlier hematoglobulin
First Known Use: 1869
HEMOGLOBIN Defined for English Language Learners
Definition of hemoglobin for English Language Learners
: the part of blood that contains iron, carries oxygen through the body, and gives blood its red color
HEMOGLOBIN Defined for Kids
Definition of hemoglobin for Students
: a protein of red blood cells that contains iron and carries oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs
Medical Definition of hemoglobin
1: an iron-containing respiratory pigment of vertebrate red blood cells that functions primarily in the transport of oxygen from the lungs to the tissues of the body, that consists of four polypeptide chains of which two are of the type designated alpha and two are of one of the types designated beta, gamma, or delta and each of which is linked to a heme molecule, that combines loosely and reversibly with oxygen in the lungs or gills to form oxyhemoglobin and with carbon dioxide in the tissues to form carbaminohemoglobin, that in humans is present normally in blood to the extent of 14 to 16 grams in 100 milliliters expressed sometimes on a scale of 0 to 100 with an average normal value (as 15 grams) taken as 100, and that is determined in blood either colorimetrically or by quantitative estimation of the iron present—see fetal hemoglobin, hemoglobin a; compare carboxyhemoglobin, methemoglobin
2: any of numerous iron-containing respiratory pigments of various organisms (as invertebrates and yeasts)
hemoglobinicor chiefly British
hemoglobinousor chiefly British
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