USA Biology Olympiad (USABO) Practice Exam

Which two centers control mammalian respiration?

1. Medulla oblongata and thalamus

2. Cerebellum and pons

3. Medulla oblongata and pons

4. Hippocampus and medulla oblongata

The correct answer is: Medulla oblongata and pons

Mammalian respiration is primarily regulated by two critical areas in the brainstem: the medulla oblongata and the pons. The medulla oblongata plays a significant role by controlling the basic rhythm and automatic patterns of breathing. It houses the ventral respiratory group (VRG) and dorsal respiratory group (DRG), which work together to signal muscles involved in respiration, such as the diaphragm. The pons also contributes to respiratory control by modulating the signals coming from the medulla. Specifically, it includes the pneumotaxic center, which helps to fine-tune the breathing rate and rhythm by influencing the transition between inhalation and exhalation. This coordination between the medulla and pons allows for the maintenance of effective ventilation in response to various physiological demands, such as exercise or altered carbon dioxide levels in the blood. Other regions mentioned in the options, like the thalamus and cerebellum, do not play a direct role in controlling respiration. The thalamus primarily functions as a relay center for sensory information and the cerebellum is essential for motor control and coordination but does not have a direct impact on the respiratory rhythm. Similarly, the hippocampus is associated with memory and learning rather than respiration. Thus