Question

The PO2 and PCO2 of blood leaving the lungs is kept remarkably constant. This homeostasis is maintained by adjusting the magnitude, or volume, of respiration. Thus, it follows that changes in the magnitude of respiration are influenced by changes in P_O2 and P_CO2 in the body.

Of these two gases, changes in ____(1)___ are the most important in regulating the magnitude of ventilation. A rise in the partial pressure of this gas triggers the body to __(2)____ the magnitude of ventilation. Which of the following statements correctly describes the major mechanism by which this has is monitored?
(1) PO2 or PCO2
(2) decrease or increase
A. Peripheral chemoreceptors in the carotid arteries monitor changes to CO_2 levels in the arterial blood.
B. Peripheral chemoreceptors in the carotid arteries monitor changes to P_CO2 levels in the arterial blood.
C. Central chemoreceptors in the medulla monitor changes to H^+ levels in the extracellular fluid
D. Central chemoreceptors in the medulla monitor changes to CO_2 levels in the extracellular fluid.

Answer 1

1. Partial pressure of Carbon dioxide or PCO₂

2. A rise innthe partial pressure of Carbon dioxide triggers the body to increase the magnitude of ventilation.

A. Peripheral chemoreceptors in the carotid arteries monitor changes to CO2 levels in the arterial blood.

Step-by-step explanation:

Breathing or ventilation refers to the process by which the gases oxygen and carbon dioxide are exchanged in the body through the lungs.

The most important function of breathing is to supply oxygen to the body as well as the removal of the the carbon dioxide produced in the body during respiration. Since oxygen and carbon dioxide are both gases, their concentration in the lungs are given as their partial pressures. The partial pressure of carbon dioxide (PCO2) in the lungs, or its concentration in the body, controls the magnitude or rate of respiration.

The peripheral chemoreceptors located in the carotid arteries detect and monitor changes in the levels of carbon dioxide in the arterial blood. An increase in arterial levels of CO2 when detected, is passed as signals from the peripheral chemoreceptors along nerves to the respiratory groups of the respiratory center, which then induces an increase in the movement of the respiratory muscles especially the diaphragm. Thus, respiration rate is incresed to remove CO2 and bring in oxygen.