Why does the animal die immediately when the medulla oblongata is damaged?

Brain damage does not always lead to death. The brain is an important organ, but some of its parts can be removed without obvious harm to the body. There are special operations when an entire hemisphere can be removed and a person continues to live normally, think, have memory, feelings, and so on. Such surgeries are performed when the brain is damaged due to illness or tumor. But the medulla oblongata, if damaged, causes death within a few minutes. This is due to the fact that this part of the brain regulates breathing and blood circulation.