1. Neurotransmitters (page 44)
Brain chemicals that communicate information throughout our brain and body using neurons to relay signals.
Tell your heart to beat, your lungs to breathe, your stomach to digest, and they can affect your mood / sleep / concentration / weight…
Levels of neurotransmitters can be affected by things such as stress, diet, trauma, caffeine, drugs, alcohol.

2. There are 2 types:
Excitatory : these stimulate the brain
Inhibitory: do not stimulate the brain. They calm the brain and help to create balance. They balance mood and are easily used up when the excitatory neurotransmitters are overactive.

3. Autonomic Nervous System
2 parts: one part that detects an issue and stimulates excitatory neurotransmitters to be released and have an effect, and a second part that detects the changes and releases inhibitory neurotransmitters to balance out the effect of the excitatory
See page 60 for a specific example.