The brain stem controls a number of basic bodily processes that are necessary for life. According to Brain-Guide.org, the brain stem functions as an autopilot for the human body, as it regulates such activities as breathing, digestion, heart rate, blood pressure and arousal. Additionally, the brain stem, which is located at the junction of the spinal cord, serves as a conduit through which information and instructions pass.
Brain-Guide.org explains that three primary components form the brain stem. The medulla oblongata controls a number of reflex actions. These include coughing, swallowing and vomiting. Additionally, the medulla oblongata serves as a relay system, and it plays a large part in carrying nerve impulses to and from the brain. Finally, the medulla oblongata controls cardiac, breathing and motor functions.
The body’s visual and auditory reflex centers are situated in the part of the brain stem called the midbrain. Brain-Guide.org says that the pons, the third and final portion of the brain stem, contains the respiratory center, which controls the body's breathing reflex. The pons also serves as another relay center, carrying impulses to and from the brain. The pons carries messages between the medulla oblongata and the advanced portions of the brain, called the higher cortical structures.