What part of the brain regulates vital functions such as heart rate and breathing?

The brainstem is the correct choice as it plays a crucial role in regulating vital functions, including heart rate and breathing. It is composed of several structures that connect the brain to the spinal cord and is responsible for controlling many of the body’s automatic and involuntary functions. The brainstem encompasses the medulla oblongata, which specifically controls autonomic functions such as breathing, heart rate, and blood pressure.

In contrast, the cerebral cortex is involved in higher-level functions such as cognition, perception, and voluntary motor control and does not directly regulate vital autonomic functions. The cerebellum primarily manages balance, coordination, and fine motor control, while the diencephalon is involved in sensory perception and regulation of homeostasis but does not directly oversee respiratory and cardiovascular functions. Understanding the specific roles of these brain structures helps clarify why the brainstem is essential for vital function regulation.