Which brain part is responsible for controlling heart rate?

The brain stem is the correct answer because it contains vital centers that regulate autonomic functions essential for survival, including heart rate. Specifically, the medulla oblongata, which is a part of the brain stem, plays a crucial role in controlling heart rate and blood pressure by integrating signals from the body and adjusting the activity of the cardiovascular system accordingly. It responds to various inputs, such as changes in carbon dioxide levels in the blood, to initiate the appropriate autonomic responses that modulate heart rate.

The cerebellum, on the other hand, primarily coordinates voluntary movements and maintains posture and balance, making it less relevant in the regulation of automatic functions like heart rate. The hypothalamus plays a role in various physiological processes, such as temperature regulation and hormone release, and it does have some influence on heart rate through its connections with the autonomic nervous system, but it is not the primary control center for heart rate. The cerebrum is involved in higher brain functions, including thought and action, and does not play a direct role in regulating heart rate. Therefore, the brain stem stands out as the central player in the control of heart rate and other involuntary functions.