Question

Which of the following statement is incorrect ?

• A. Expiratory centre lies in pons and inspiratory centre lies in medulla
• B. The inspiratory centre increases the strength of contraction of rib muscles
• C. Breathing movements are caused by change in concentration of $C{O}_2$ in the blood
• D. Pneumotaxic centre controls the switch off point of inspiration

Answer 1

The correct option is A Expiratory centre lies in pons and inspiratory centre lies in medulla

A specialized centre present in the medulla region of the brain called respiratory rhythm centre is primarily responsible for the regulation of respiratory rhythm, that means inspiration and expiration are regulated by medulla.
Pneumotaxic centre can moderate the functions of the respiratory rhythm centre. Neural signal from this centre can reduce the duration of inspiration and thereby, alter the respiratory rate.
A chemo sensitive area is situated adjacent to the rhythm centre which is highly sensitive to $C{O}_2$ and hydrogen ions. Change in $C{O}_2$ concentration if increased leads to faster and deeper breathing movements and if decreased leads to slower and calmer breathing movements.
The inspiratory centre increases the strength of contraction of rib muscles. As it increases the size of the thoracic cavity, the pressure inside gets decreased.

So, the incorrect statement is- option a.