Exocrine Pancreas Flashcards
Endocrine secretion
Insulin
Glucagon
Exocrine secretion
Bicarbonate
Enzymes
Pancreatic Islets
Alpha cells
Beta cells
To bloodstream
What do alpha cells secrete
Glucagon
What do beta cells secrete
Insulin
Acini cells
Secrete enzymes to pancreatic duct
Centrocinar cells
Ductable cells
CFTR channel
What do centrocinar cells produce
HCO3-
Function of ductable cells
HCO3- and Cl- exchange
Zymogen of trypsin
Trypsinogen
Zymogen of chymotrypsin
Chymotrypsinogen
Proteases released from the pancreas
Trypsin and chymotrypsin (in inactive form)
Where are proteases activated
Small intestine
What activates trypsinogen and chymotrypsinogen
Enterokinase
Where is enterokinase found
On epithelial cell walls
Function of proteases
Digests proteins and peptides (not to amino acids)
What activates trypsinogen
Enterokinase
Trypsin - positive feedback loop
Function of pancreatic lipase
Triglyceride digestion by hydrolysis to produce monoglycerides and free fatty acid chains
Steatorrhea
Fatty stools
Pancreatic insufficiency of pancreatic lipase
Function of amylase
Hydrolyses starch to maltose and dextrins
Pancreatic enzymes
Trypsin
Chymotrypsin
Pancreatic lipase
Amylase
Gelatinase
Elastase
Ribonuclease
Deoxyribonuclease
Primary pancreatic enzyme secretion
NaHCO3
Secondary pancreatic enzyme secretion
HCO3- is exchanged for Cl-
Fluid composition of enzyme secretions
Dependent of flow rate
The faster it flows the less exchange of HCO3- and Cl- so it is richer in HCO3- and lower in Cl-
Na+ and K+ levels do not change
Functions of pancreatic bicarbonate secretion
Protects duodenal mucosa by neutralising acid
Buffers duodenal contents
Optimises pH for enzyme digestion
Resting phase- bicarbonate secretion
Low flow
Predominantly Na+ and Cl-
High flow bicarbonate secretion
Mainly Na+ and HCO3-
Average flow of bicarbonate secretion per day
1 L
Which nerve stimulates release of pancreatic enzymes
Vagus
HCO3- rich component of pancreatic secretions
Mainly stimulated by production of acid in the stomach
Neutralising effect
Stimulated by secretin and CCK
Which phase of gastric motility is most dominant in pancreatic enzyme secretion
Intestinal phase
Enzymatic component of pancreatic secretion
Secreted from Acinar cells in response to an increased intracellular Ca2+ concentration
Produced by ACh from vagal stimulation
CCK secreted from small intestine can stimulate enzyme release
Cholecystokinin stimulus
HCl
Proteins and fats in duodenum
Production of cholecystokinin
I cells of duodenum and Jejunum
Action of cholecystokinin
Pancreatic enzyme and HCO3- secretion
Gallbladder contraction- causing bile secretion
Inhibition of gastric acid secretion
Delays gastric emptying (aid digestion0
Secretin stimulus
Low duodenal pH
Secretin production
Upper small intestine
Action of secretin
Pancreatic water and HCO3- secretion - carries the enzymes
Alllows enzymes to work in small intestine as it raises the pH
Gastrin stimulus
Gastric distension and irritation
Gastrin production
G cells in stomach
Action of gastrin
HCl secretion (parietal cells)
Enzyme release (Acinar cells)
Which cells secrete pancreatic enzymes
Acinar cells
What causes Acinar cells to secrete pancreatic enzymes
Increased intracellular Ca2+ concentration
What increases Ca2+ concentration in Acinar cells
ACh from vagal stimulation
Orlistat
Pancreatic lipase inhibitor
Enzyme secretion- Cephalic phase
Cephalic stage- vagal innervation
Low level stimulus in anticipation of a meal
Enzyme secretion - intestinal stage
Secretin
Cholecystokinin
Gastrin
Symptoms of pancreatic exocrine symptoms
Maldigestion
Diarrhoea
Steatorrhoea
Weight loss
Pancreatic exocrine insufficiency prevalence
11000 adults/year in uk develop PEI
Pancreatic exocrine insufficiency consequences
Malnutrition
Osteoporosis
Increased cardiovascular morbidity
Symptoms burden
Pancreatic exocrine insufficiency - parenchymal diseases
Chronic pancreatitis
Acute pancreatitis
Cystic fibrosis
Pancreatic cancer
Autoimmune pancreatitis
Pancreatic exocrine insufficiency - extra-pancreatic diseases
Coeliac disease
IBD
Diabetes
Zollinger-Ellison
Ampullary obstruction
Pancreatic exocrine insufficiency
Reduction in pancreatic enzyme activity in the intestinal lumen below the threshold required to maintain normal digestion
Pancreatic exocrine insufficiency - post surgical states
Gastric resection
Whipple’s
Short bowel syndrome
Post bariatric surgery
Assessment of pancreatic function
History, risk factors
Imaging
Faecal elastase
Markers of malnutrition
Treatment of Pancreatic exocrine insufficiency
Pancreatic enzyme replacement therapy
Stop smoking
Bone health assessment
Treat the underlying cause
Pancreatic exocrine insufficiency mechanisms
Loss of parenchyma cells
Obstruction of secretion
Type 3c diabetes
develops when your pancreas experiences damage, such as from chronic pancreatitis or cystic fibrosis.
People with Type 3c diabetes often also have a lack of pancreatic enzymes that are important for digestion.
Type 3c diabetes is manageable with oral diabetes medications and/or insulin.
Which receptors activate pancreatic enzyme and bicarbonate secretion
M1 and M3 muscarinic receptors
Which 2 enzymes are secreted from the pancreas in their active form
Amylase
Lipase
Pepsin is an important digestive enzyme. Which of the following statements concerning pepsin is true?
It hydrolyses bonds between aromatic amino acids