Which section of the brain controls basic life functions such as respiration and cardiac rhythm?

The brain stem plays a crucial role in regulating basic life functions necessary for survival, including respiration, heart rate, and blood pressure. It acts as a vital relay center for signals between the brain and the spinal cord, coordinating many autonomic functions. The brain stem comprises several key structures, including the midbrain, pons, and medulla oblongata, each contributing to these essential physiological functions.

In contrast, the cerebellum is primarily involved in motor control and coordination, while the cerebrum is responsible for higher brain functions, including thought, action, and sensory processing, but not directly in regulating autonomic functions. The thalamus, on the other hand, serves as a hub for relaying sensory and motor signals to the cerebral cortex but does not control basic life functions. Therefore, the brain stem is the correct answer, as it oversees the crucial systems that keep the body performing vital tasks essential for life.