Question

Choose the incorrect statement with respect to breathing and respiration in humans:

• A. The volume of the thoracic chamber increases due to the contraction of diaphragm and external inter-costal muscles.
• B. $O_2$ and ${\mathrm{CO}}_2$ transports in the blood majorly through RBCs and as bicarbonate, respectively.
• C. High ${\mathrm{pO}}_2$, low ${\mathrm{pCO}}_2$, lesser $H^{+}$ concentration and lower temperature promotes formation of oxyhaemoglobin.
• D. ${\mathrm{CO}}_2$ and $H^{+}$ concentration is insignificant and oxygen plays a huge role in the regulation of respiratory rhythm.

Answer 1

The correct option is D ${\mathrm{CO}}_2$ and $H^{+}$ concentration is insignificant and oxygen plays a huge role in the regulation of respiratory rhythm.

The mechanism of breathing includes increasing the volume of the thoracic chamber which will reduce the pressure inside the chamber in comparison to the atmosphere.

This pressure difference allows inspiration and expiration. Contraction of diaphragm and intercostal muscles increases the volume in antero-posterior axis and dorso-ventral axis, respectively.

97% of $O_2$ and 70 % of ${\mathrm{CO}}_2$ are carried in blood by RBCs and as bicarbonate ions, respectively.

$O_2$ can bind with haemoglobin in a reversible manner to form
oxyhaemoglobin. High p$O_2$ , low ${\mathrm{pCO}}_2$ , lesser $H^{+}$ concentration and lower temperature conditions are seen in alveoli in lungs. That's why formation of oxyhaemoglobin is promoted in lungs.

Neural system controls the respiratory rhythm to meet the demands of the body. The functions of respiratory rhythm centre in medulla are moderated by pneumotaxic centre in the pons. A chemosensitive area near the rhythm centre senses the change in concentration of ${\mathrm{CO}}_2$ and $H^{+}$ ion. Hence, change in $O_2$ concentration doesn't regulate the respiratory rhythm.