Part of team brain response to survival is an outpouring of stress hormones like norepinephrine and cortisol that flood the body during stress. Like the amygdala, they also help us survive. Let’s see how they work.
A collection of brain cells (or neurons) in the brain stem (the part of the brain at the back of your neck that controls basic functions like breathing and being awake) contains the majority of the stress hormone, adrenaline, in the brain. Technically, it is known as noradrenaline (norepinephrine) when it occurs in the brain and adrenaline (epinephrine) in the body, but I refer to both using the commonly known term “adrenaline.”
These brain cells have long fibers, known as axons, that extend their tentacles throughout the brain, and release adrenaline everywhere all at once. This release is triggered by a scary event, like the attack of a lion.
Adrenaline is released from the end of the axon into the space between it and the next neuron, called the synapse. It then boogies on over to the next neuron and says “help, help!” That makes the next neuron get off its duff and tell the rest of the brain gang that trouble is brewing.
Adrenaline acts like a chemical messenger that says “RUN!!”
Adrenaline is the Brain’s Fire Alarm System
When there’s a fire, you run and pull an alarm that tells everyone in the building to get out right away. The idea is to tell everyone to leave, both the people who might get burned and those who are not at risk. There will be time to sort that out later, but in the short term it is better to make sure that everyone is safe.
Our brains and bodies have their own fire alarm system. It’s called adrenaline. When there’s a threat, adrenaline is released everywhere, signals all parts of the brain to pay attention, and triggers all parts of the body to be ready. Adrenaline makes blood pressure go up and heart rate increase so that you can deliver more blood to your brain, muscles, and the other parts of the body important to survival. You breathe faster so you get more oxygen into your lungs and then your blood. More blood means more oxygen and more energy (sugar) to help those body parts work better, so you can run faster and fight harder.
Cortisol Chips In
At the same time that your adrenaline system is firing, corticotropin releasing factor (CRF) is released from a part of the brain called the hypothalamus. This triggers a chain reaction which results in the release of the stress hormone, cortisol, from the adrenal gland.
Cortisol helps to move energy to the muscles so we can fight back or run away fast. It does this by moving energy away from areas that aren’t needed for survival, like the stomach (you don’t need to digest your lunch right away) or reproductive organs. Fast thinking and strong muscles are critical to survive at that split second when we are under attack.
Too Much of a Good Thing
We need the hormones cortisol and adrenaline to help us survive, but if we are under stress for too long, or there are too many traumatic events, they can get out of whack.
In some cases, CRF and adrenaline can be chronically too high; as well, minor stressors or things that trigger memories of stress may cause you to release way too much cortisol and norepinephrine. The cortisol system may get burnt out, it might not have the right rhythm, or it might be depleted at certain times of the day.
The fear part of the brain, the amygdala, may be over-active, and the parts of the brain involved in memory and emotion and turning off the fear response (the hippocampus and frontal cortex) may not turn on normally. You might use alcohol and drugs to turn off these stress hormones and quiet your brain so that you don’t feel so anxious, but that can become a problem in itself. We will talk more about brain areas involved in stress later on.