Malabsorption & Maldigestion Flashcards
What 3 proteases are produced by the exocrine pancreas?
1) Trypsin
2) Chymotrypsin
1+2 both convert proteins to polypeptides
3) Carboxypolypeptidases
What 3 lipases are produced by the exocrine pancreas?
1) Pancreatic lipase
2) Cholesterol esterase
3) Phospholipidase
What is produced by the pancreas to help with carbohydrate digestion?
Pancreatic amylase
Why is it important for the pancreas to produce bicarbonate?
Because the bicarbonate neutralises the HCl coming from the stomach and provides a suitable environment for pancreatic enzymes to work.
What is the difference between maldigestion and malabsorption?
Maldigestion = when normal digestion is impaired whereas malabsorption is when nutrients are digested normally but cannot be absorbed.
What is malassimilation?
When maldigestion and malabsorption both occur at the same time
Aside from maldigestion of proteins, carbohydrates and lipids, what else can malassimilation cause?
- Impaired assimilation of fat soluble vitamins
- Impaired absorption of cobalamin
- Increased bacterial growth in the small intestine
What are 4 fat soluble vitamins?
Vitamin A
Vitamin D
Vitamin E
Vitamin K
What causes increased bacterial growth in the gut?
When chyme lies undigested in the upper GI tract, it provides a growth media for bacteria.
Intrinsic factor is essential to permit cobalamin absorption, where is it produced?
Intrinsic factor is synthesised by the pancreas
How does exocrine pancreatic insufficiency (EPI) affect intrinsic factor production?
EPI - stops production.
What happens to cobalamin absorption when there is increased number of bacteria in the gut?
Bacteria take up all of the cobalamin and do not leave enough for the body.
Why do we need cobalamin?
Important for correct functioing of nerve cells and red blood cells.
How is cobalamin absorbed in the ileum?
1) Cobalamin binds to R proteins secreted by the salivary glands and gastric mucosal cells
2) In the duodenum, protease removes/ cleaves the R protein and cobalamin binds to an intrinsic factor.
3) Cobalamin then undergoes receptor mediated transport in the ileum.
What are the 4 causes of maldigestion?
- Exocrine pancreatic insufficiency
- Secondary enzyme insufficiency
- Deficiency of bile acid
- Loss of brush border enzymes
What is exocrine pancreatic insufficiency (EPI)?
Insufficient production of pancreatic enzymes.
What do acinar cells do in the pancreas?
Produce enzymes for the exocrine pancreas.
What are the 4 causes of EPI?
1) Pancreatic acinar atrophy
2) Pancreatitis (inflammation)
3) Pancreatic hypoplasia (decreased size)
4) Pancreatic neoplasia
What is pancreatic acinar atrophy (PAA)?
Destruction of acinar cells.
Can have stage 1 and stage 2 of PAA
Stage 1 = Partial acinar atrophy
Stage 2 = Severe, end stage.
What is chronic pancreatitis?
Progressive destruction of exocrine and endocrine pancreas
What are some of the clinical signs of EPI?
- Weight loss
- Increased faecal volume
- Flatulence
- Abnormal faeces
- Coprophagia
What is the best diagnosis method for EPI?
- TLI blood test (trypsin-like immunoreactivity)
EPI would cause low TPI levels in blood
How can EPI be treated?
Restricted fat diet
Give pancreatic enzyme replacement
What are the 3 phases of absorption in the small intestine?
1) Luminal
2) Mucosal
3) Transportation
What pathology can affect the luminal phase?
(Phase refers to micelles in the lumen of the SI)
- Dysmotility (motility can be sped up or slowed down)
- Pancreatic enzyme deficiency
- Fat maldigestion
What pathology affects the mucosal phase?
(Phase affects the brush border in the SI)
- Brush border enzyme deficiency
- Brush border protein transport deficiency
- Enterocyte defects
What pathology can affect the transport phase?
- Lymphatic obstruction
- Obstruction due to neoplasia/ inflammation
- Vascular compromise
- Hepatopathy (right sided heart failure)
What is primary GI disease?
Refers to infiltrative diseases of the gut wall
What are the main 3 clinical signs of primary GI disease?
Weight loss, diarrhoea, coprophagia
What is secondary GI disease?
- Linked to hepatic disease (bile acids not working properly)
- Right sided cardiac disease
- Hyperthyroidism (decreases gut transit time)
