Why the blood is red?

Why the blood is red?

PROF WAQAR HUSSAIN

          

 Human body contains about 5.5 dm³ (liter) blood which is red as it contains cells which are red. Why these cells are red? They are red due to protein haemoglobin which is transition metal complex containing iron ion (II or III) in the centre. Haemoglobin upload oxygen from the lungs and passes through 60,000 miles network of blood vessels and capillaries and ultimately reaches the door of 6 trillion cells,

knocks the door and delivers oxygen to every cell that is used by the cell to oxidize glucose to H₂O and CO₂ and Energy. Cell makes use of this energy for its survival and other functions. On return, haemoglobin carries CO₂ and transports it to lung and shows it the way out.

             Iron ion in the core of hemoglobin has the property of reflecting red light and there is so much iron in our blood, which make the blood to appear red. When hemoglobin is carrying a lot of oxygen (oxygenated blood), the colour of blood is bright red. When most of the oxygen has been released to the body, blood (deoxygenated blood) becomes dark red. It is contrary to 

popular belief that deoxygenated blood is blue. In fact, veins under light coloured skin only look blue because the skin changes the optical properties of the light that passes through the skin. 

A VISUAL MODEL OF OXYGEN BINDING PROCESS