Question

Blood carbon dioxide levels determine the $pH$ of other body fluids as well as blood, including the $pH$ of cerebrospinal fluid. How does this enable the organism to control breathing?

• A. The brain directly measures and monitors carbon dioxide and causes breathing changes accordingly.
• B. The medulla, which is in contact with cerebrospinal fluid, monitors $pH$ and uses this measure to control breathing
• C. The brain alters the $pH$ of the cerebrospinal fluid to force the animal to retain more or less carbon dioxide
• D. Stretch receptors in the lungs cause the medulla to speed up or slow breathing

Answer 1

Answer: (B)

Correct answer is (b) The medulla, which is in contact with cerebrospinal fluid, monitors $pH$ and uses this measure to control breathing