foraging for berries under the hot East African sun.
Suddenly, a lion appears in your periphery—let’s pretend
for the sake of the story this lion’s name is Mufasa. Mufasa
hasn’t eaten in days, nor has his hungry cub back at the
pride (let’s call him Simba). Mufasa sees you as the perfect
meal to break his fast and feed his cub—rich in protein,
calories, and omega-3s—and begins hurtling toward you at
full speed.
At this moment, your amygdala, which is essentially
your brain’s lookout deck, kicks your sympathetic nervous
response into motion, priming your body for action. The
amygdala activates something called the hypothalamic–
pituitary–adrenal (HPA) axis, causing the adrenal glands to
secrete cortisol and epinephrine (also known as adrenaline),
and suddenly, your mellow day of flower picking becomes
an all-out sprint for your life.
THE HPA AXIS—THE STRESS RESPONSE
SWITCHBOARD
Once initiated, the HPA axis begins in the brain structure
known as the hypothalamus—the H in HPA. One of the
most important functions of the hypothalamus (aside from
its role as a metabolic master controller) is to link the brain
to the body’s hormone system via the pituitary gland. The
hypothalamus sends out some corticotropin-releasing
hormone (CRH) to the pituitary gland—the meat in the HPA
sandwich. After receiving word of turmoil from the
hypothalamus, the pituitary gland then secretes something