EMSWORLD.com | OCTOBER 2015 33
into systemic circulation via the inferior vena cava.
As such, the blood supplied to the liver is brought
into contact with hepatocytes, which perform the
majority of functions performed by the liver (Table
1). Bile produced by the hepatocytes drains into bile
canaliculi and then the hepatic ducts on its way to
storage in the gallbladder.
Simply put, the liver is like a large, blood-filled
sponge that receives an ample supply of blood from
both the hepatic arteries and the portal vein. For
blood to move easily through this sponge and come
into contact with hepatocytes and Kupffer cells, the
functional units of the liver (the lobules) must be
unobstructed and allow for proper flow. When this
occurs, the liver can perform its required functions.
Physiology of the Liver
The liver provides numerous essential functions in
the body; some sources claim more than 200. These
many roles can be broken down into three basic cat-
egories: metabolic regulation; hematologic regulation;
and synthesis and secretion of bile.
1
Metabolic Regulation
The liver plays a major role in the metabolic regula-
tion of many body functions. All the blood leaving
the absorptive areas of the digestive tract (stomach,
small and large intestines) enters the hepatic portal
system and flows into the liver. This gives the liver
the opportunity to extract ingested and absorbed
nutrients, metabolic waste products and toxins from
Esophageal vein
Liver with
cirrhosis
Gastric
vein
Portal
vein
Superior
mesenteric
vein
Esophageal
varices
Gastric
varices
Spleen
Fran Milner, www.franimation.com
ABOUT THE
AUTHORS
Scott R.
Snyder,
BS,
NREMT-P,
is full-
time
faculty at
the Public Safety Training
Center in the Emergency
Care Program at Santa
Rosa Junior College, CA.
He is also a paramedic
with AMR: Sonoma Life
Support in Santa Rosa,
CA. E-mail scottrsnyder@
me.com.
Sean M.
Kivlehan,
MD, MPH,
NREMT-P,
is an inter-
national
emer-
gency medicine fellow
at Brigham & Women's
Hospital, Harvard Medical
School. E-mail sean.
kivlehan@gmail.com.
Kevin T.
Collopy,
BA, FP-C,
CCEMT-P,
NREMT-P,
WEMT,
is clinical
education coordinator
for VitaLink/AirLink in
Wilmington, NC, and
a lead instructor for
Wilderness Medical
Associates. E-mail
ktcollopy@gmail.com.