The urge to inhale in humans result from (a) rising pCO2 (b) rising pO2 (c) falling pCO2 (d) falling pO2
p stands for partial pressures. I am guessing the answer is falling pCO2.... but I wanted what is the answer and the reason for it?
The correct answer would be a) rising pCO2. The rising CO2 level in the blood causes an urge to inhale and take in more O2.
For how it works, this is controlled by respiratory center:
The respiratory centers (RC) are located in the medulla oblongata and pons, which are part of the brain stem. The RCs receive controlling signals of neural, chemical and hormonal nature and control the rate and depth of respiratory movements of the diaphragm and other respiratory muscles ... In healthy individuals the presence of elevated carbon dioxide levels in the blood is the stimulant that the RC responds to in order to signal the respiratory muscles to breathe. Chemoreceptors found in carotid bodies and aortic bodies are responsible for detecting decrease in blood pH by this carbon dioxide.