The pancreas has both exocrine and endocrine functions. It develops from ventral and dorsal buds and contains head, neck, body and tail regions. The pancreas secretes enzymes to aid digestion and hormones like insulin and glucagon to regulate blood sugar. Secretion is controlled by various hormones and neural pathways in response to eating to facilitate digestion and maintain glucose homeostasis.
2. Pancreas- Brief History
• Pancreas – derived from the Greek pan, “all”,
and kreas, “flesh”, probably referring to the
organ’s homogenous appearance
• Herophilus, Greek surgeon first described
pancreas.
• Wirsung discovered the pancreatic duct in 1642
• Pancreas as a secretory gland was investigated
by Graaf in 1671
• R. Fitz established pancreatitis as a disease in
1889
• Whipple performed the first pancreatico-
duodenectomy in 1935 and refined it in 1940
3. Embryology of pancreas
• Endo dermal origin
• Develops from ventral and dorsal pancreatic
buds
• Ventral bud becomes the uncinate process and
inferior head of pancreas
• Dorsal bud becomes superior head, neck, body
and tail
• Ventral bud duct fuses with dorsal bud duct to
become main pancreatic duct (Wirsung)
• Pancreas divisum
4.
5. Pancreas
• Gland with both exocrine and endocrine
functions
• 15-20 cm in length
• 70-100 gram in weight
• Location: retro-peritoneum, 2nd lumbar vertebral
level
• Extends in an oblique, transverse position
• Parts of pancreas: head, neck, body and tail
6. Head of pancreas
• Broadest part
• Nestled into the C-loop
of duodenum and
posterior to transverse
mesocolon
• Lies over the inferior
venacava, the right and
left renal veins at the
level of L2
• Posterior surface is
indented by the terminal
part of the bile duct
7. Uncinate process
• Lower part of the
posterior surface of
the head prolongs as
uncinate process
behind the superior
mesenteric artery and
vein in front of the
aorta
8. Neck of pancreas
• Lies in front of the
superior mesenteric
and portal veins
9. Body of the pancreas
• Body passes across the
left renal vein and aorta,
left crus of diaphragm, left
psoas muscle, lower pole
of left suprarenal gland to
the hilum of left kidney
• Upper border crosses the
aorta at the origin of the
celiac trunk
• Splenic artery passes to
the left along the upper
border
• Lower border crosses the
origin of the superior
mesenteric artery
10. Body of the pancreas
• Splenic vein is closely applied to the posterior
surface
• Inferior mesenteric vein joins the splenic vein
behind the body of the pancreas
11. Tail of the pancreas
• Passes forward from the anterior surface of the
left kidney at the level of hilum
• Lies within two layers of the lienorenal ligament
along with splenic artery, vein, lymphatics and
touches the hilum of spleen
12. Pancreatic duct
• Duct of Wirsung – continuous tube leading from
the tail to the head
• Joined by the bile duct at 60 degrees at the
hepatopancreatic ampulla
• Diameter is 2-3mm
• In intubation during ERCP, the catheter
preferentially enters the pancreatic duct
• Drains most part of the pancreas except for the
uncinate process and lower part of head which
drains by the duct of Santorini
• Accessory duct opens into the duodenal papilla
situated about 2 cm proximal to the major papilla
13.
14. Blood supply of Pancreas
• Splenic artery supplies neck, body and tail
• Superior and inferior pancreaticoduodenal
arteries supply head
• Venous return into the splenic vein, superior
pancreaticoduodenal vein into the portal vein
and inferior pancreaticoduodenal vein into the
SMV
15.
16.
17. Lymph drainage
• Lymphatics follow the course of the arteries
• Retro pancreatic nodes
• Celiac group
• SMV group
20. Pancreatic physiology
• Exocrine pancreas 85% of the volume of the
gland
• Extracellular matrix – 10%
• Blood vessels and ducts - 4%
• Endocrine pancreas – 2%
21. Exocrine system
• Consists of two functional units :
– Acinar cells which secrete primarily digestive
enzymes
– Centroacinar or ductal cells which secrete
fluids and electrolytes
• Pancreatic secretion is regulated by several
peptides that are released from the GIT – either
inhibits or stimulates secretion by the pancreas
• 90% of the gland need to be destroyed to
produce maldigestion and serious nutritional
deficiencies
22. Exocrine
• Pancreatic enzyme is a clear isotonic solution
with a pH of 8 and specific gravity varies
between 1.007 and 1.035
• At lower secretory rates the concentrations of
chloride and bicarbonate ions are equivalent to
plasma
• With neurohormonal stimulation, the bicarbonate
component increases in concentration while the
chloride concentration falls
• Sodium and potassium in the effluent remains
constant
23. Bicarbonate secretion
• Isosmotic juice 1500-3000 ml/day
• pH range 8 – 8.5
• Total concentration of major anions – chloride &
Bicarb approaches 150mEq/L
• At maximum output, chloride concentration <50
mEq/L whereas Bicarb concentration reaches
150 mEq/L
• High pH neutralizes acidic gastric chyme and
provides optimum pH for the enzymatic digestion
24. Exocrine
• The principal stimulant of pancreatic water and
electrolyte secretion – Secretin
• Secretin is synthesized in the S cells of the
crypts of Liberkuhn
• Released into the blood stream in the presence
of luminal acid and bile
25. Enzyme secretion
• Once trypsinogen is activated it activates further
zymogens
• Lipolytic enzymes
– Secreted in active form
– Lipase is the major component
– Hydrolyzes triglycerides
• Amylase is a carbohydrate-hydrolyzing enzyme
and acts on starch
26. Regulation of Pancreatic Secretion
• Two patterns of secretion
– Basal secretion
• Bursts of increased bicarbonate and
enzyme secretion that last 10 to 15 minutes
– Post prandial stage
• Divided into cephalic phase, gastric phase,
intestinal phase
27. Post Prandial stage
• Cephalic phase
– Occurs in response to the sight or taste of
food
– Mediated by the vagus
– Results in the production of enzymes and
bicarbonate
28. Post Prandial stage
• Gastric phase
– Occurs partially in response to distension of
stomach which stimulates gastrin release by
vagal reflex
– Gastrin and neural reflex stimulate acid
secretion by gastric parietal cells and
pancreatic enzyme secretion
29. Post Prandial stage
• Intestinal phase
– Initiated in response to acid entering the
duodenum
– Most important phase
– When pH falls <4.5 secretin is released from
the intestine
– Secretin inturn stimulates the pancreatic ducts
to secrete bicarbonate
– Presence of fatty acid, oligopeptides and
amino acids results in release of CCK which
increase secretion of pancreatic enzymes
30. Endocrine pancreas
• Principal function is to maintain glucose
homeostasis
• Insulin and glucagon play a major role in
glucose homeostasis
• In addition endocrine pancreas secrete
somatostatin, pancreatic polypeptide, amylin
31.
32. Conclusion
• Pancreas is a composite gland
– Has exocrine and endocrine function
• Plays major role in digestion and glucose
homeostasis
