Fight or flight response studied first hand
David Schwartz for the Big Sky Weekly

Third and fourth year medical school
students are displaced from the classroom
and sent out to experience the
practice of medicine firsthand. This is
a time to learn how the human body
reacts to external forces, and how to
assist a person back to health when
presented with a threat to his or her
body. This July, while working at the
Medical Clinic of Big Sky, I had an
encounter that gave me a new respect
for how humans interact with their
After work one night I set out with
my friend and classmate, Matt,
to catch the evening hatch on the
Gallatin River. Maybe I should have
brought my bear spray, I thought,
stomping through a marshy meadow
and eight-foot willows. But being
within sight and earshot of Big Sky
somehow gave me a false sense of
As the sun descended below the
ridge, we fished, and when I could no
longer see my caddis fly I reeled in. I
started up the bank to find my buddy,
who’d evidently walked the opposite
direction upriver.
Something caught my eye across
the river. I stopped to investigate
the strange shape through the low
light and determined quickly it was
neither a tree nor a rock. It turned
sideways, revealing a large shoulder
hump. I froze.
I’ve learned about “fight or flight,”
but now I understand the feeling
beneath that famous phrase. The
fight or flight response is triggered
by fear, and is the human body’s
natural defense mechanism.
The nervous system can be divided
into two main branches: the sympathetic
and the parasympathetic.
The common term “adrenaline
rush” is more specifically defined
as a release of hormones called catecholamines
from the center of the
adrenal gland. It happens so quickly
because the adrenal medulla is innervated
by the sympathetic branch
of the nervous system – a direct
connection from the brain to the
adrenal medulla.
Once the catecholamines epinephrine
and norepinephrine are released into
the bloodstream, physiologic responses
take place: The heart rate and
respiratory rates increase; the pupils
dilate to let more light in; the central
vasculature constricts; the muscular
vasculature dilates, and the body
readies itself for action. Theoretically,
this prepares us to face a threat.
The griz made its way up the opposite
bank, and I walked downriver and
into the willows, glancing constantly
over my shoulder and feeling helpless
without my bear spray.
I stumbled through the marsh and
back to the highway. When I met
Matt at the car, I saw in his face he
hadn’t seen the bear. I shared the
experience with him and felt calmed
by his normal mental state.
The opportunity to rotate at the
Medical Clinic of Big Sky is a unique
experience for medical students. We
connect with the natural world and
experience medicine in a beautiful
setting not offered by mainstream
educational institutions. We’ve
learned many things here in Big Sky,
and neither Matt nor I will be caught
dead without bear spray the next time
we wander to the river’s edge to wet
a line.

David Schwartz is a forth year medical
student at Kansas City University
of Medicine and Biosciences. He
spent a month in Big Sky this summer
doing a rotation at the Medical
Clinic of Big Sky.