Anatomy & physiology of pancreas

Anatomy & Physiology
of the Pancreas
Sanjay George

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

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.

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.

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.

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.

Blood Supply
Arterial:
Pancreatic Branches of splenic
artery
Superior pancreaticoduodenal artery
Inferior pancreaticoduodenal artery
Venous:
Drain into splenic, superior
mesenteric and portal veins

Lymphatics
Head & Neck – Pancreaticoduodenal
Body & Tail - Pancreaticosplenic

Nerve Supply
Parasympathetic – Vagus
Sympathetic – plexuses around
its arteries

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

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.

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.

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

Contd..
Hormones:
Insulin
Glucagon
Somatostatin

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.

Anatomy & physiology of pancreas

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Anatomy & physiology of pancreas