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PANCREAS ANATOMY
esophagus
stomach
ductus choledocus
pancreas
duodenum
duct of
Santorini
duct of
Wirsung
PANCREATIC SECRETIONS
1. PROTEASES (70%)
Endopeptidases (trypsin, chymotrypsin, elastases)
Exopeptidases (carboxypeptidases)
trypsinogen
trypsin
activates all other precursors
enterokinase
(duct walls)
2. NUCLEASES (DNAase, RNAase)
3. PANCREATIC AMYLASE (hydrolyse starch and gl;ycogen)
4. PANCREATIC LIPASE (triglycerides
fatty acids and glycerol)
REGULATION OF SECRETION
1. SECRETIN
food in
stomach
release of
stomach acid
into duodenum
release of secretin
into blood by
duodenal cells
secretion of
bicarbonate
by duct cells
alkaline pH
(ideal for
pancreatic enzymes)
2. PANCREOZYMIN (cholecystokinen)
amino acids and
fats in intestine
release of pancreozymin
by intestinal mucosa
into blood
relase of pancreatic enzymes
into the intestine
3. GASTRIN
food in stomach
gastrin secretion
by stomach mucosa
4. AUTONOMIC INNERVATION (vagus nerve)
release of pancreatic enzymes
into the intestine
PANCREAS (PANORAMIC)
islet of
Langerhans
pancreatic acini
islet of
Langerhans
pancreatic lobe
BV
PANCREATIC SECRETORY DUCTS
LARGE SECRETORY DUCT
INTERLOBULAR DUCT
simple
cuboidal
epithelium
acinus
simple
columnar
epithelium
EXOCRINE PANCREAS
pyramidal
secretory
basal basophilia
cell
(rough ER)
acinus
merocrine secretion
(exocytosis)
zymogen
granules
centroacinar
cells
blood
vessel
condensing
vacuoles
golgi
vesicles
intercalated
duct
rough
endoplasmic
reticulum
nerve
interlobular
duct
zymogen
granules
golgi
apparatus
INTERCALARY DUCTS AND CENTROACINAR CELLS
intercalary duct
centroacinar
cell
intercalary
duct
PANCREATIC EXOCRINE SECRETORY CELL
zymogen
granules
centroacinar
cell
CELL BIOLOGY OF PANCREATIC SECRETION
1. SYNTHESIS
2. SEGREGATION
14
C -leucine + tRNA
mRNA for
chymotrysinogen
14
C-amino-acyl tRNA
ribosomes
mRNA
ribosomes
polypeptide
chymotrysinogen
RER cisterna
6. DISCHARGE
3. INTRACELLULAR TRANSPORT
exocytosis
RER
transitional
elements
5. INTRACELLULAR
STORAGE
zymogen
granules
4. CONCENTRATION
golgi
apparatus
H2O
H2O
condensing vacuoles
golgi vesicles
EXPERIMENTAL METHODS IN CELL SECRETION
1. SUBCELLULAR FRACTIONATION
(grind and find)
2. RADIOAUTOGRAPHY
(cook and look)
developed silver grains
density
gradient
centrifugation
photographic
emulsion
vesicles
microsomes
(RER)
golgi
condensing
vacuoles
zymogen
granules
ultrathin
section
pancreatic
acinar cell
(3 mins)
cpm
14
C
leucine
(7 mins)
cpm
C
leucine
cpm
C
leucine
14
RER golgi
cond
zymogen
(80 mins)
14
RER golgi
pulse chase
cond zymogen
RER golgi
cond
zymogen
ISLET OF LANGERHANS
alpha cell
(glucagon)
vascular pole
(secretion by exocytosis)
acinus
beta cell
beta
cell
(insulin)
fenestrated
capillary
blood
capillary
INSULIN- increases membrane
permeability to glucose
GLUCAGON - promotes glycogenolysis
promotes glycogenesis
decrease blood glucose levels
increases blood glucose levels
“ ANTAGONISTIC HORMONES”
alpha
cell
ISLET OF LANGERHANS
ISLET OF LANGERHANS - TEM
STAINED ALPHA AND BETA CELLS
ALPHA CELLS
BETA CELLS