Question

Which of the following mechanisms is invovled in the homeostatic control that allows respiration to return to normal after exercise.

A) Sensors in the carotid arteries repsonde to the increasing levels of oxygen in blood during recovery after exercise

b) sensors in the medulla oblongata repsond to a decrease in pH of cerberospinal fluid

c) Sensors in the aorta detect that blood pH returns to pH 7.4, and sends decreased neuronal signals tot he medulla oblongata.

d) sensors in the rib muscles detect the decreasing carbon dioxide levels and hence stimulate them to contact less frequently.

E) decreased neruonal signals from the adrenal medulla tot he rib muscles and diaphragm allows repsiration to go back to normal

Answer 1

Respiration is regulated by respiratory control center of brain. The amount of oxygen consumed is always equal to amount of carbon dioxide expelled out of body and thus maintains homeostasis during respiration. Heavy physical work or exercise requires more oxygen and as a result, the oxygen levels of blood are decreased increasing the carbon dioxide levels. The respiratory control center senses these changes and increase the heart rate and also rate of breathing. When the exercise is stopped, the changes in gases are sensed by respiratory control center and thus the heart and breathing rate of regulated back to homeostasis. Thus, the sensors in aorta detect the changes in gases and blood pH and when pH becomes normal, the neuroinal signals to medulla oblongata or respiratory cointrol center are reduced restoring homeostasis. option C is correct.