A large proportion of oxygen is left unused the human blood even after its uptake by the body tissue. This `O_(2)`

A large proportion of oxygen is left unused in the human blood even after its uptake by the body tissues. This O_2

A large proportion of oxygen is left unused in the human blood even after its uptake by the body tissues.This O_2 :

A large proportion of oxygen remain unused in the human blood even after its uptake by the body tissues. This O_(2)

A large proportion of oxygen remains unused in the human blood even after its uptake by the body tissues. This O_2

Where does the blood absorb oxygen in the human body ?