The given graph shows an oxygen dissociation curve for haemoglobin.

Wher is the body will haemoglobin be saturated at the percentage shown at point `1,2` and `3` in graph ?

Options

A. `{:("Left ventricle","Pulmonary vein","Vena cava"),(1,2,3):}`
B. `{:("Left ventricle","Pulmonary vein","Vena cava"),(2,1,3):}`
C. `{:("Left ventricle","Pulmonary vein","Vena cava"),(2,3,1):}`
D. `{:("Left ventricle","Pulmonary vein","Vena cava"),(3,2,1):}`

Answer

C

Explanation

The relationship between the partial pressure of `O_(2) (PO_(2))` and percentage saturation of the Hb with `O_(2)` is graphically illustrated by a curve called oxygen dissociation curve. The haemoglobin is most saturated with oxygen in the pulmonary vein, as this vein is carrying oxygenated blood from the lungs towards the left auricle of the heart. From the left auricle the blood moves to the left ventrcile where saturation of Hb with `O_(2)` slightly reduces. Vena cava carries deoxygenated blood from all the organs of the body towards right auricle, thus, Hb is less saturated with `O_(2)`.