Blood and Oxygen

• Human haemoglobin is found in red blood cells - it carries oxygen around the body. 
• It is a large protein with a quaternary structure - it has four polypeptide chains. Each chain has a haem group which contains iron and gives it it's red colour. 
• Each molecule can carry four oxygen molecules. 
• In the lungs, oxygen joins to the iron to form oxyhaemoglobin. 
• This is a reversible reaction. 
• When an oxygen molecule joins it is known as association or loading. and when it leaves it is dissociation or unloading.

Oxygen does not dissolve well so oxygen is carried by haemoglobin in the red blood cells. 

The partial pressure of oxygen (paO2) is the measurement of oxygen in arterial blood and shows how well the oxygen is able to move from the lungs to the blood. 

At higher altitudes, increases in atmospheric pressure result in a drop in the pressure of your blood gases, including the partial pressure of oxygen. The lower…