Question

Which of the following conditions is responsible for the increase in the ventilation rate of the lungs?
A. Increase of $C{O_2}$ content in inhaled air.
B. Increase of $C{O_2}$ content in exhaled air.
C. Decrease of ${O_2}$ content in inhaled air.
D. Decrease of content in exhaled air.

Answer 1

Hint: The movement of air into and out of the lungs is referred to as ventilation. In other words, ventilation controls breathing. Respiration which is facilitated by ventilation is the process of utilizing oxygen and balancing carbon dioxide by the body.

Complete answer: Respiratory rate is controlled by partial pressure of carbon dioxide $p(C{O_2})$ or the concentration of carbon dioxide. Changes in the level of oxygen and carbon dioxide are detected by the peripheral chemoreceptors. These chemoreceptors are located in the arterial aortic bodies and the carotid bodies. Changes in the pH of blood are brought about by changes in the levels of carbon dioxide. Central chemoreceptors that are sensitive to this change are located on the medulla oblongata near the medullary respiratory center. A condition where abnormally elevated carbon dioxide levels are present in the blood is referred to as hypercapnia. Hypercapnia is also known as hypercarbia or carbon dioxide retention. A rise in $pC{O_2}$ results in the decrease of pH levels in the cerebrospinal fluid.
So, the correct option is A, ie., Increase of $C{O_2}$ content in inhaled air.
Additional information: -
Hypercapnia may be acute hypercapnia or chronic hypercapnia. Acute hypercapnia or the sudden increase in carbon dioxide levels is more dangerous the kidneys are unable to handle the rise. Chronic hypercapnia is seen in chronic obstructive pulmonary disease affected patients. Depending on the severity of the condition, hypercapnia can be treated by ventilation, medication, oxygen therapy, lifestyle changes, and surgery.

Note: When there is inadequate ventilation the pH drops and there is an increase in levels. As a result of the rise in carbon dioxide, the respiratory centers are stimulated to increase the rate and depth of respiration to remove the excess carbon dioxide.