haemoglobin

he·mo·glo·bin

(Hgb, Hb) (hē'mō-glō'bin)

The red respiratory protein of erythrocytes, consisting of approximately 3.8% heme and 96.2% globin, with a molecular weight of 64,450, which as oxyhemoglobin (HbO₂) transports oxygen from the lungs to the tissues where the oxygen is readily released and HbO₂ becomes Hb. When Hb is exposed to certain chemicals, its normal respiratory function is blocked; thus, oxygen in HbO₂ is easily displaced by carbon monoxide, a process that results in the formation of fairly stable carboxyhemoglobin (HbCO), as in asphyxiation resulting from inhalation of exhaust fumes from gasoline engines. When the iron in Hb is oxidized from the ferrous to ferric state, as in poisoning with nitrates and certain other chemicals, a nonrespiratory compound, methemoglobin (MetHb), is formed.
Synonym(s): haemoglobin.

Medical Dictionary for the Health Professions and Nursing © Farlex 2012

haemoglobin

The iron-containing protein that fills red blood cells. Haemoglobin combines readily but loosely with oxygen in conditions of high oxygen concentration, as in the lungs, and releases it when in an environment low in oxygen, as in the body tissues. In health, each 100 ml of blood contains 12–18 g of haemoglobin. The various genetically induced abnormalities of haemoglobin are called HAEMOGLOBINOPATHIES.

Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

haemoglobin

a large PROTEIN molecule with a quaternary structure of four POLYPEPTIDES CHAINS, two alpha and two beta chains, each of which is complexed to a separate HAEM group. About 300 million molecules of haemoglobin occur in each red blood cell of the mammalian circulation, with each molecule binding to a maximum of four oxygen molecules, one per haem group (= oxygenation). See OXYGEN-DISSOCIATION CURVE for an explanation of oxygen carriage. Haemoglobin is found in all vertebrates and many invertebrates. In mammals the foetal haemoglobin (HbF) has a different polypeptide combination from that in postnatal ‘adult’ haemoglobin (HbA), consisting of two alpha and two gamma chains, with different oxygen-carrying characteristics (up to 30% more at low oxygen tension). An altered beta chain in HbA produces SICKLE-CELL ANAEMIA.

Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

he·mo·glo·bin

(Hb) (hē'mō-glō'bin) [MIM*141800142310, MIM*141800]

Red respiratory protein of erythrocytes. In humans, there are at least five kinds of normal Hb: two embryonic Hbs (Hb Gower-1, Hb Gower-2), fetal (Hb F), and two adult types (Hb A, Hb A₂).
Synonym(s): haemoglobin.

Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about haemoglobin

Q. haemoglobin deficiency Haemoglobin deficiency - 6.3 rbc count less than normal range. platelets are 157000

A. what you describe here is pretty harsh numbers. very very low hemoglobin, low platelets level...have you checked for white blood cells? i recommend seeing a Dr. ASAP. with these numbers there is a good chance that you'll bleed from places that are not supposed to bleed.

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