What part of the brain is responsible for regulating heartbeat and breathing?

The medulla oblongata is a critical structure located in the brainstem that plays an essential role in regulating several autonomic functions necessary for survival, including heartbeat and breathing. It contains vital centers that automatically control these processes without the need for conscious thought. In addition to regulating the heart rate and the rhythm of breathing, the medulla oblongata is involved in other functions like blood pressure regulation and reflex actions such as swallowing, coughing, and sneezing.

The cerebellum, situated at the back of the brain, is primarily responsible for motor control, coordination, balance, and fine-tuning movements, but it does not directly regulate heart rate or respiration. The cerebrum, which is the largest part of the brain, is involved in higher brain functions like thought, emotion, and voluntary activities. The hypothalamus, located below the thalamus, regulates a wide range of functions including temperature control, hunger, and sleep cycles, as well as the body's stress response, but it does not directly control heartbeat and breathing. Hence, the medulla oblongata is the correct answer for its dedicated role in autonomic regulation.