CHAPTER 16
Digestive Glands and Associated Organs
315
Pancreas
Islet of
Islet of
Langerhans
Langerhans
Islet of
Langerhans
Intralobular
Intralobular
ducts
ducts
Intralobular
ducts
Centroacinar
Centroacinar
cell
cell
Centroacinar
cell
Pancreatic
Pancreatic
acini
acini
Pancreatic
acini
B
Figure 16-9B.
Exocrine and endocrine pancreas.
H&E,
3
272
The
pancreas
consists of
exocrine
and
endocrine
portions
. The
exocrine pancreas
has many serous secretory cells, which stain
darkly, as in the major salivary glands. These secretory cells are often
called
pancreatic acinar cells
and are arranged as acini. Each pancre-
atic acinar cell has a round nucleus and its cytoplasm contains many
zymogen granules
(see Fig. 16-10A). These cells secrete enzymes that
help in the digestion of proteins, lipids, and carbohydrates. The pan-
creas is innervated by parasympathetic nerve ±
bers from the right
branch of the
vagus nerve
(
CN X
).The
endocrine pancreas
, known as
the
islets of Langerhans
, is found within the exocrine pancreas. The
islets produce the hormones
insulin
and
glucagon
, which are released
into the bloodstream to regulate blood glucose level. The endocrine
portion of the gland does not have a duct system (see Chapter 17,
“Endocrine System”).
CLINICAL CORRELATION
Figure 16-9C.
Acute Pancreatitis.
H&E,
3
50
Acute pancreatitis
is an acute infl
ammatory disease of the pancreas
characterized by severe upper abdominal pain, nausea and vomiting,
and elevated
serum pancreatic enzymes
,
amylase
and
lipase
. Acute
pancreatitis may be caused by
hypertriglyceridemia
, alcohol ingestion,
infections, trauma, drugs, and
gallstones
. Gallstones may block the pan-
creatic duct, resulting in
autodigestion
of the pancreatic parenchyma
by enzymes released because of disrupted cell membranes. Pathologic
changes include interstitial and peripancreatic edema, fat necrosis with
saponi±
cation
, infl
ammatory in±
ltration of neutrophils, and
necrosis
of
the
pancreatic parenchyma
. Based on the severity of the disease, treat-
ment includes pain control, intravenous fl
uids, nasogastric suction, and
reduction of food intake. In very severe cases, surgical removal of the
damaged tissue may be necessary. This image shows acute pancreatitis
with
fat necrosis
, an acute infl ammatory in±
ltrate consisting of neutro-
phils, and infl
amed pancreatic parenchyma.
Fat
necrosis
Pancreatic
parenchyma
tissue
Acute
inflammation
(neutrophils)
C
Figure 16-9A.
A representation of the exocrine pancreatic duct system.
The
pancreas
is an elongated gland, which lies mostly posterior to the stomach (see Fig. 16-1). It can be divided into a
head
,
body
, and
tail
. The pan-
creatic duct begins in the tail of the pancreas, passes through the body, and enters the head of the pancreas. Most exocrine pancreatic secretions are
carried by the
main duct
, which joins the bile duct of the gallbladder at the
hepatopancreatic ampulla
and empties the secretions into the duodenum
through the
major duodenal papilla
. A small portion of the pancreatic secretion is released into the duodenum through the minor duodenal papilla.
The exocrine portion of the gland has a duct system that is similar to that of the major salivary glands, except the pancreas does not have striated
ducts and lobar ducts. Secretory products are released into the smallest portions of the intercalated ducts, formed by centroacinar cells, and then
drained into the intralobular ducts, the interlobular ducts, and ± nally into the main duct.
D.Cui
T. Yang
Centroacinar
cells
Small intralobular
(intercalated)
ducts
Large
intralobular
duct
Pancreatic
acini
Main
duct
Interlobular
duct
Tail
Body
Main
duct
Head
Hepatopancreatic
ampulla
Major duodenal
papilla
Bile duct
Gallbladder
Minor
duodenal
papilla
Main
duct
Interlobular
duct
A
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