Oxyhaemoglobin
Definition
The form of haemoglobin in freshly shed arterial blood, where iron in the haem group is in the ferrous (Fe²⁺) state and bound to oxygen. Responsible for the bright red colour of fresh blood.
- Iron oxidation state
- Ferrous (Fe²+)
- Fresh blood color
- Bright red
- Deep tissue appearance
- Dark red-purple
Common questions
Why is fresh blood bright red?+
Fresh blood appears bright red because of oxyhaemoglobin, where iron in the haemoglobin molecule is in the ferrous (Fe²+) state and bound to oxygen. This red color is one of the first signs you observe in a new wound or bloodstain.
What is the difference between the color of a fresh bruise and an old one?+
A fresh bruise in deep tissue appears dark red-purple because of oxyhaemoglobin. As the bruise ages, the haemoglobin undergoes chemical changes that produce different colors, helping investigators estimate when the injury occurred.
How does oxyhaemoglobin form in blood?+
Oxyhaemoglobin is the natural form that exists in freshly shed arterial blood. The iron in the haem group stays in its ferrous state and binds to oxygen molecules, creating the characteristic bright red color of fresh blood.
Related terms
- Bilirubin
- A yellow-orange breakdown product of biliverdin, seen as the yellow-brown phase of a resolving bruise. Its appearance indicates advancing haemoglobin degradation.
- Biliverdin
- A green breakdown product of haemoglobin, appearing as the blue-green phase of bruise colour change. Biliverdin is then converted to bilirubin.
- Cross-polarised photography
- A photographic technique using polarising filters on both the light source and the camera lens to eliminate surface glare and reveal subsurface...
- Haemichrome
- A further oxidation product formed when the globin chains of methaemoglobin denature and the haem group becomes internally coordinated. Associated with the...
- Haemoglobin
- The iron-containing protein in red blood cells that carries oxygen. Its peroxidase-like activity is the basis of most presumptive blood tests; its...
- Methaemoglobin
- An oxidised form of haemoglobin in which ferrous iron (Fe2+) is converted to ferric iron (Fe3+), unable to carry oxygen. Its formation...
- Photodegradation
- Breakdown of biological molecules driven by ultraviolet and visible radiation. In bloodstains it accelerates haemoglobin oxidation and cleaves DNA strands, hastening ageing...
- Protein denaturation
- Unfolding and cross-linking of protein structure under heat, desiccation, or chemical stress. Affects haemoglobin, albumin, and other blood proteins as a stain...
- Substrate effect
- The influence of the surface on which a bloodstain lies on the rate and character of chemical change. Porous substrates absorb blood...
- Tissue laxity
- The looseness of subcutaneous tissue. High laxity (eyelids, scrotum, elderly skin) allows blood to spread widely from a relatively small vessel injury,...
Explained in these topics
- Ageing of Bruises: Methods and LimitationsThe initial form of haemoglobin in fresh blood, giving the bright red colour of a new wound. In deep tissue it appears as a dark red-purple bruise.
- Physical and Chemical Changes in Ageing BloodstainsThe form of haemoglobin in freshly shed arterial blood, where iron in the haem group is in the ferrous (Fe²⁺) state and bound to oxygen. Responsible for the br...