| Response | Level of Arousal | Nervous System Activated | Neuro-anatomy Endocrine System |
| Fight | Increased (hyper) | Sympathetic | - H.P.A Axis - Adrenaline |
| Flight | Increased (hyper) | Sympathetic | - H.P.A Axis - Adrenaline |
| Fright | Increased (hyper) | Sympathetic | - H.P.A Axis- Adrenaline |
| Freeze | Decreased (hypo) | Unmyelinated branch of vagus | Post-ganglionic muscarinic nerves -acetylcholine |
| Faint (vaso- vagal syncope) | Decreased (hypo) | Unmyelinated branch of vagus | Acetylcholine |
| Feigned death | Decreased (hypo) | Unmyelinated branch of vagus | Acetylcholine |