If the co₂ level in blood rises above a preset limit, how will the respiratory center adjust the breathing to compensate?
a. decrease rate and depth of respiration
b. decrease rate and increase depth of respiration
c. increase rate and decrease depth of respiration
d. increase rate and depth of respiration

D

Explanation:

The respiratory center is located in the medulla oblongata, Pons and Brainstem.They are three major  group of respiratory neurons which are two in the medulla and one in the pons.

The adjustment of breathing  by the respiratory center is by Negative feedback mechanism. As the blood flow through the medulla its (Central Chemoreceptors) constantly detect fluctuations in the blood pH.  The fluctuation in Oxygen or Carbon dioxide levels  are detected by the peripheral chemoreceptors.

 Chemoreceptors are specialized sensory cells which convert chemical substance to biological signals

The drop in pH (high acidity of the blood), stimulated the medulla to send signals to the three respiratory group of the respiratory center.The respiratory center send signals to the respiration muscles; the diaphragm, and the external and internal intercoastal muscles to contract and relax the rib cage and the lungs

These mechanism increases the rate and depth of breathing,  so that the C02 levels of the blood drops by exhaling C02 from the  lungs (since the reaction of C02 and H20  from Carbonic acids (HCO3)  that lowered the pH)

.

However when the blood pH returns to normal the Cenrtral chemoreceptors detect this and respiratory group  in the medula reduces the signals to the  respiratory muscles through the pons varolli; to return breathing to normal rate