What stimulates the chemoreceptors to function?
A.
Increase in blood pressure
B.
Decrease in heart rate
C.
Pulmonary congestion
D.
Rise in CO2 and fall in O2.
The Correct answer and Explanation is:
The correct answer is D. Rise in CO2 and fall in O2.
Chemoreceptors are specialized sensory receptors that respond to chemical changes in the blood. They play a crucial role in regulating respiratory rate and depth by detecting changes in blood gases, specifically carbon dioxide (CO2) and oxygen (O2) levels.
Central Chemoreceptors: These receptors are located in the medulla oblongata of the brainstem. They primarily respond to changes in the pH of cerebrospinal fluid (CSF), which is influenced by CO2 levels in the blood. When CO2 levels rise, it diffuses into the CSF, where it reacts with water to form carbonic acid. This reaction lowers the pH of the CSF, and the central chemoreceptors detect this decrease in pH. In response, they signal the respiratory centers in the brainstem to increase the rate and depth of breathing to expel CO2 and restore normal pH levels.
Peripheral Chemoreceptors: These receptors are located in the carotid bodies (near the bifurcation of the common carotid arteries) and the aortic bodies (in the aortic arch). They are sensitive to changes in blood O2 levels, CO2 levels, and pH. A significant drop in O2 (hypoxemia) and an increase in CO2 (hypercapnia) stimulate these chemoreceptors. When these receptors detect low O2 levels or high CO2 levels, they send signals to the respiratory centers to increase ventilation. This response helps to restore adequate oxygen levels and remove excess CO2 from the bloodstream.
In summary, chemoreceptors are stimulated primarily by a rise in CO2 levels and a fall in O2 levels. These changes signal the need for increased ventilation to maintain proper gas exchange and acid-base balance in the body. This mechanism ensures that the body responds effectively to imbalances in blood gases, maintaining homeostasis and overall respiratory health.