What are the 2 big things are happening in the brain?

the Cerebrum and brain stem

Explanation:

The brain stem controls your lungs and heart and blood pressure. It sits at the top of the spine and receives messages from the rest of the body. In some ways this is the most important part of the brain because it keeps you alive.

Cerebrum since it controls vital functions such as breathing, swallowing, digestion, eye movement and heartbeat, there can be no life without it. But the rest of the brain is obviously capable of some remarkable feats, with one part able to compensate for deficiencies in another.

obviously, the latter.