Question 12 - Biological and Biochemical Foundations of Living Systems Practice Test for the MCAT

According to the attached passage, why is the output of the negative feedback loop for oxygen demand located at the diaphragm?

Oxygen deprivation produces symptoms such as fatigue, headaches, and confusion that are collectively referred to as hypoxia. A vacation in the Rocky Mountains of the US, where the partial pressure of oxygen is just 15% lower than you are accustomed to on the coast, can induce these symptoms. The body has a very narrow range of environment oxygen tolerance. It essentially has no capacity for storage of oxygen that is continuously consumed to maintain energy homeostasis.

The response to oxygen deprivation is to increase breathing rate and increase the volume of each breath. The input for a negative feedback loop that maintains homeostasis by detecting oxygen concentrations is a sensor (the carotid body) located on the interior of the carotid artery. The output is at the diaphragm. The signal is processed in the respiratory centers (RCs) of the medulla in the brainstem.

Retrieved from: Eggebrecht,J., & Zedalis,J.(2018) Biology for AP® Courses. OpenStax.

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