The pancreas is a 15-20cm long organ located in the retroperitoneum. It has a head, body, and tail. The pancreas contains exocrine tissue that produces enzymes to aid digestion and endocrine tissue clustered in islets of Langerhans that produce hormones like insulin and glucagon. The pancreas develops from dorsal and ventral buds that fuse during embryogenesis. It receives blood supply from various arteries and drains into veins like the portal vein. The pancreas secretes enzymes and bicarbonate to digest nutrients in the small intestine. Removal of the pancreas results in diabetes and digestive issues due to lack of enzymes.
2. Anatomy
Derived from ‘Pan’ – all ‘Kreas’ –
flesh
15-20cm long, 2.5 – 3.8cm
broad, 1.2 – 1.8cm thick
Weighs 80g
Situated in retroperitoneum
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4. Contd..
Divided:
Head – 30%
Body and Tail – 70%
Head corresponds with the curve of duodenum
overlying the body of the 2nd lumbar vertebra and
the venacava.
Aorta and superior mesenteric vessels lie behind
the neck.
Near upper border of neck superior mesenteric
vein joins splenic vein to form portal vein.
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6. Contd..
Coming of side of pancreatic head
and passing to the left and behind
superior mesenteric vein is uncinate
process.
Tip of pancreatic tail extends upto the
splenic hilum.
7. Histology
80-90% of pancreatic tissue – Exocrine acinar tissue
organised as lobules
Pancreatic duct Interlobular & Intralobular ducts
ductules acini
Main duct – Columnar cells
Ductules – Cuboidal cells
Acinar cells clumped around central lumen which
communicates with duct system.
8. Histology
Clusters of endocrine cells distributed throughout called
Islets of Langerhans
Islet:
75% - B Cells – Insulin
20% - A Cells – Glucagon
5% - D Cells – Somatostatin
Small number of pancreatic polypeptide cells
B cells form inner core surrounded by other cells.
Capillaries draining islet cells drain into portal vein.
9. Blood Supply
Arterial:
Pancreatic Branches of splenic
artery
Superior pancreaticoduodenal artery
Inferior pancreaticoduodenal artery
Venous:
Drain into splenic, superior
mesenteric and portal veins
12. Embryology
Time Event
1 Day 26 Dorsal Pancreatic duct arises from dorsal side of
duodenum
2 Day 32 Ventral Bud arises from base of hepatic diverticulum
3 Day 37 Contact occurs between the 2 buds. Fusion by end of 6th
week
4 Week 6 Ventral bud produces the head and uncinate process
5 Week 6 Ducts Fuse
6 Week 6 Ventral duct and distal portion of dorsal duct form the
main duct
7 Week 6 Proximal duct forms the duct of Santorini
8 Month 3 Acini appear
9 Months 3-4 Islets of Langerhans Appear & become active
13. Embryology
Malrotation of ventral bud in 5th week –
annular pancreas.
Mode of ductule fusion in 7th week
produces various possible ductular
patterns.
Anatomy of main duodenal papilla –
ampulla of vater is also variable.
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18. Physiology
In response to food – secretes digestive
enzymes in an alkaline bicarbonate rich
fluid.
Secretion enhanced by:
Secretin
Cholecystokinin
Vagal Stimulation
Within cells enzymes are in inactive form.
19. Pancreatic Secretions
Electrolytes:
Cations: Na+, K+, Ca2+, Mg2+, Zn2+
Anions: HCO3-, Cl- and traces of SO42-, HPO42-
Enymes:
Pancreatic alpha-amylase
Pancreatic lipase
Pancreatic esterase
Pancreatic pro-phospholipase A2
Pancreatic proteolytic enymes:
Trypsinogen
Chymotrypsin
Pro – carboxypeptidase A and B
Ribonuclease
Deoxy-ribonuclease
Pro-elatase
Trypsin inhibitor
21. Total Removal of Pancreas
Diabetes mellitus due to pancreatic
endocrine deficiency of insulinn
Development of digestive disturbances:
Increase of faecal fats – bulky, foul
smelling, pale and greasy stools
Increased faecal nitrogen due to
incomplete proteolysis
No abnormality of carbohydrate digestion
Pancreatic insufficiency – loss of 30% of
calorific value of ingested food.