the midbrain is the central location of neurotransmitters involved primarily in arousal, mood and motivation. The brain structures also rely on them. This part also orients the brain from or towards pleasureable or threatening stimuli in the environment. HIndbrain on the other hand functions to take the bodily processes needed to sustain living of a person.
The pH of the stomach in the digestive system is known to be very low, and acidic, so it can break the bonds between molecules, to which the nutrients diffuse into your blood, energizing you.