Final answer:
The medulla oblongata is the part of the brain that sends signals to the diaphragm to regulate inhalation and exhalation, mainly through the actions of the dorsal and ventral respiratory groups. It adjusts the breathing rate in response to carbon dioxide levels in the blood.
Step-by-step explanation:
The correct answer to the question is B) Medulla oblongata. The medulla oblongata, part of the brainstem, contains various respiratory centers that are crucial for the process of breathing. Notably, the dorsal respiratory group (DRG) and the ventral respiratory group (VRG) located within the medulla oblongata play significant roles. The DRG primarily maintains a constant rhythm of breathing by sending signals to the diaphragm and intercostal muscles to contract, causing inhalation. Once the DRG stops its activity, the muscles relax, leading to exhalation. On the other hand, the VRG is involved in forced breathing such as that after exercise or during stressful conditions.
The control of breathing is a complex mechanism that involves not only the medulla oblongata but also the pons and certain chemoreceptors that monitor the levels of carbon dioxide in the blood. When these levels rise, the respiratory centers increase the rate and depth of breathing to expel the excess carbon dioxide. Conversely, decreased carbon dioxide levels will reduce the need for oxygen intake, leading to slower and shallower breaths.
While the hypothalamus and the limbic system do influence the regulation of breathing in relation to emotions, pain, and temperature, they are not primarily responsible for the initiation of the breathing cycle. Therefore, the answer to this question focuses on the medulla oblongata, which houses the essential respiratory centers like DRG and VRG for normal respiration.