Final answer:
The medulla oblongata contains the dorsal respiratory group (DRG) and the ventral respiratory group (VRG), which are responsible for controlling breathing rhythm and forced breathing.
Step-by-step explanation:
The part of the brain that contains centers for the heartbeat and respiration is the medulla oblongata. It contains the dorsal respiratory group (DRG) and the ventral respiratory group (VRG). The DRG is responsible for maintaining a constant breathing rhythm, while the VRG is involved in forced breathing.