Question

Select all the answers that are true for chemoreceptors located in the carotid bodies and aortic arch:

a.Sense levels of PCO₂ surrounding the brain tissues.
b.Sense arterial blood levels of PO₂ and PCO₂
c.Sense PO₂ when it drops below the normal 100 mmHg.
d.Sense PO₂ delivered to the tissues.
e.Sense only PCO₂ (not PO₂).
f.Sense PCO₂ of the arterial blood.
g.Once activated, respond quickly to regulate respiratory rate

Answer 1

Chemoreceptors in the carotid bodies and aortic arch monitor arterial levels of oxygen (PO2 below 60 mmHg) and carbon dioxide (PCO2), and signal the brain to modulate respiration accordingly.

Step-by-step explanation:

The chemoreceptors located in the carotid bodies and aortic arch are specialized in detecting changes in blood levels of oxygen (PO2), carbon dioxide (PCO2), and pH. These peripheral chemoreceptors sense arterial blood levels of both PO2 and PCO2. They are particularly responsive to PO2 when it drops significantly below the normal range, not just below 100 mmHg but around 60 mmHg or less. Importantly, they are only able to sense dissolved oxygen molecules, not the oxygen carried by hemoglobin in blood.

Moreover, these chemoreceptors also sense the PCO2 of arterial blood and they play a critical role in the regulation of respiratory rate. When exposed to changes in PCO2, acidity (pH), or critically low levels of PO2, they quickly signal the respiratory centers in the medulla oblongata to adjust breathing patterns accordingly.