Which structure forms the lowest part of the brainstem and regulates bodily functions like heart rate?

The medulla oblongata is indeed the structure that forms the lowest part of the brainstem and plays a crucial role in regulating vital bodily functions, including heart rate, breathing, and blood pressure. It acts as a center for autonomic functions, managing processes that are essential for survival without conscious control. The medulla also serves as a pathway for information traveling between the brain and spinal cord, ensuring that signals coordinating bodily functions are effectively communicated.

The pons, located above the medulla, is involved in regulating sleep and arousal, and it acts as a bridge between different parts of the nervous system but does not directly control heart rate. The cerebellum, situated at the back of the brain, primarily coordinates voluntary movements and balance, rather than autonomic functions. The midbrain is associated with functions such as vision, hearing, and motor control but is not responsible for managing heart rate or other autonomic bodily functions.