Question

When central chemoreceptors detect an increase in the pH of the cerebrospinal fluid:

A. cerebellar respiratory centers trigger an increase in rate and depth (volume) of breathing
B. medulla and pons trigger a decrease in rate and depth (volume) of breathing
C. The cerebrum trigger a decrease in rate and depth (volume) of breathing
D. the occipital lobe causes the diaphragm to increase contraction rate
E. the corpus callosum sends signals to the lungs

Answer 1

Central chemoreceptors monitoring the pH of CSF will cause the medulla and pons to decrease the rate and depth of breathing when there is an increase in pH, indicating lower carbon dioxide and hydrogen ion levels in the blood.

Step-by-step explanation:

When central chemoreceptors detect an increase in pH of the cerebrospinal fluid (CSF), which implies a decrease in carbon dioxide and hydrogen ion concentration, the medulla and pons trigger a response to modulate respiration. An increased pH (decreased carbon dioxide and hydrogen ions) will lead to a decrease in the rate and depth of breathing. This is because the primary role of respiration is to maintain homeostasis by regulating blood pH, primarily through the expulsion of carbon dioxide which, when it accumulates, lowers the pH of the blood and CSF.

In contrast, when carbon dioxide levels in the blood rise, resulting in a drop in pH (more acidic), the central chemoreceptors stimulate the medulla oblongata to signal for an increase in the rate and depth of breathing. This helps to expel more carbon dioxide, thereby bringing the pH back towards normal. Therefore, the correct answer is B. medulla and pons trigger a decrease in rate and depth (volume) of breathing.