The part of the brain that regulates vital functions like heart rate and breathing is the medulla oblongata. Located in the brainstem, it plays a crucial role in autonomic functions, controlling involuntary actions necessary for survival. The medulla oblongata receives signals from the body and adjusts physiological responses accordingly. In addition to regulating heart rate and respiration, it is also involved in reflex actions such as swallowing and vomiting, making it essential for maintaining homeostasis.