c a l l e d adrenocorticotropic hormone (ACTH) into
circulation. (Recall that hormones are long-range
messengers, which differ from neurotransmitters, which act
neuron-to-neuron.) Now in circulation, ACTH acts on the
adrenal glands, which are perched above the kidneys. This
causes a surge in cortisol and epinephrine.

HPA Axis: Hypothalamus ➛ Pituitary gland ➛

Adrenal glands

Amygdala ➛ Hypothalamus (corticotropin-releasing

hormone [CRH]) ➛ Pituitary gland (adrenocorticotropic

hormone [ACTH]) ➛ Adrenal glands (Cortisol) ➛

Circulation

The cortisol and adrenaline that are now coursing
through your body have several effects on your physiology.
For one, heart rate and blood pressure go way up. Pupils
dilate. Salivary secretion halts and digestion slows down
(digestion is a relatively labor-intensive process, and
running from Mufasa is no time to be using precious
resources on nutrient absorption). In fact, blood leaves the
digestive area, rerouting to more important locations, like
your muscles. Blood sugar is released from the liver, and the
parts of the body that are inessential to getting you out of
harm’s way become resistant to insulin, making sure that