A large proportion of oxygen is left unsused in the human blood even after its uptake by the body tissues.…

A large proportion of oxygen is left unsused in the human blood even after its uptake by the body tissues. This $\mathrm{O}_2$
  1. raises the $p_{\mathrm{CO}_2}$ of blood to $75 \mathrm{~mm}$ of $\mathrm{Hg}$
  2. is enough to keep oxyhaemoglobin
  3. helps in relasing more $\mathrm{O}_2$ to the epithelial tissues
  4. acts as a reserve during muscular exercise

Solution

Our tissue are able to utilize only $25 \%$ of $\mathrm{O}_2$ carried by arterial blood. The venous blood is still $75 \%$ saturated with $\mathrm{O}_2$. This $\mathrm{O}_2$ acts as a reserve during muscular exercise.

Asked in: NEET 2011 (Screening)

Practice more Breathing and Exchange of Gases questions on Aicharya