PATHOPHYSIOLOGY OF DIGESTION AND ABSORPTION

advertisement
M.H.Imanieh M.D.
Pediatric Gastroenterology Department
Shiraz University of Medical Sciences
DEFINITION
Subnormal intestinal absorption
of dietary constituents and thus
excessive loss of nutrients in
the stool
Stages of Intestinal Digestion and Absorption
1. Luminal hydrolysis and solubilization
2. Hydrolysis at the enterocyte membrane
3. Absorption across the enterocyte membrane and
cellular processing
4. Uptake from the enterocyte into blood and lymph
PATHOPHYSIOLOGIC MECHANISMS
Digestion in the lumen
 Mouth :
• Saliva is important for normal digestion
• Parotid (20%), Submandibular (60%), Sublingual (20%)
• Minor salivary glands in lips, palate,tongue and cheeks
 Stomach :
• Acid (parietal cells), Pepsinogen, Lipase (chief cells), IF
 Pancreas :
• Bicarbonate ions
• Digestive Enzymes
 Liver :
Solubilization of fat
 Small intestine :
Enterokinase
Malabsorption syndromes are characterized by
chronic diarrhea (main symptom) , abdominal
distention and FTT.
PATHOPHYSIOLOGY OF DIGESTION
AND ABSORPTION
CARBOHYDRATES
Starch (50–60%)
Sucrose (30- 40%)
Lactose ( from 0-20% in adults, 40-50% in infants)
 Salivary Amylase
 Pancreatic Amylase
 Sucrase- Isomaltase
 Lactase- Glucoamylase
 Glucose- Galactose pump
 Fructose Transport
 Lipase
Lingual
Fundus
Pancreatic
 Colipase
 Bile salts
 F. acid Binding protein
 Apo protein
 Lipo protein
 Lymphatic system
 Gastric pepsinogen I, II
 Gastric pepsin I, II
 Trypsinogen






enterokinase
trypsin
Proelastase trypsin elastase
prochymotrypsinogen trypsin chymotrypsin
Proendopeptidase trypsin endopeptidase
Proexopeptidase trypsin exopeptidase
Brush border peptidase
Cytoplasmic peptidase
 Celiac disease
 Giardiasis
 Food allergy ( milk, soya, …)
 Alpha chain disease
 Hypogammaglobulinemia
 Dermatitis herpetiformis
 Bacterial overgrowth
 Eosinophilic enteritis
cont
 Regional enteritis
 Post infectious enteritis
 Radiation enteritis
 Amyloidosis
 Seleroderma
 Tropical sprue
 Mastocytosis
 Cystic fibrosis
 Chronic pancreatitis
 Pancreatic hypoplasia
 Pancreatic resection
 Schwachman syndrome
 Postgastrectomy steatorrhea
 Gastrinoma (Zollinger-Ellison syndrome)
 Lipase or colipase def.
 Trypsinogen or enterokinase def.
 Cong. Sucrase – isomaltase def.
 Cong. Lactase def.
 Late onset lactase def.
 Cong. Trehalase def.
 Cong. Glocose- galactose malabsorption
 All causes of villous atrophy
 Parenchymal liver Dx.
 Cholestasis
 Blind loop syn.
 Stricture – fistula
 Hypomotility ( DM- Pseudo obst.)
 Ileal disease (TB, Crohn, resection)
 Neomycin- cholestyramin- ca carbonate
 Lymphangiectasia
 Whipple disease
 Lymphoma
 Constrictive pericarditis
 Mesenteric vascular insufficiency
 Vasculitis
 C.H.F
 Diabetes mellitus
 Hypoparathyroidism
 Hyperthyroidism
 Adrenal insufficiency
 Gastrinoma (Zollinger-Ellison syndrome)
 Carcinoid syndrome
 Abetal lipoproteinemia
 Lymphangiectasia
 Anderson’s disease
 Wolman disease
 Abdominal distention
 Pale, foul smelling bulky stool
 Muscle wasting
 Poor Wt. gain – Wt. loss
 Subcutaneus fat loss
Sign- Symptome
Malnutrition and Wt.
loss
Diarrhea
Pathophysiology
Malabsorption of fatcarbohydrate- protein
Impaired absorption or increased
secretion of water and
electrolytes.
unabsorbed dihydroxy bile acids
and fatty acids.
Flatus
Bacterial fermentation of
unabsorbed CHO
Glossitis – cheilosis
stomatitis
Def . Of Iron- B 12 – Folate and …
Bone pain
Protein and calcium depletion
Sign- Symptome
Pathophysiology
Osteoarthropathy
Unknown
Tetany – paresthesia
Ca and mg depletion
Weakness
Anemia – hypokalemia
Periph. Neuropathy
Vit B12 and thiamine deficiency
Eczema
Unknown
Dermatitis
Def. of vit A – zinc- essential
fatty acids
Night blindness
xerophthalmia
Vit A deficiency
Sign- Symptome
Pathophysiology
Nocturia
Delayed reaborption of waterhypokalemia
Azotemia- hypotension
Fluid and electrolyte depletion
Amenorrhea, ↓libido
Protein and calori depletion 2°
hypopituitarism
Anemia
Impaired absorption of Iron- B12 –
folate
Purpura ( bleeding
tendency)
Vit. K malabsorption
DIAGNOSIS
Hx.
P/E
Lab.
 Stool PH and reducing substance
 H2 breath test
 Oral tolerance test
 Stool osmolality
 Mucosal activity of disacharidases
 D- xylose test
 Stool alpha- 1 antitrypsin
 Chromium labeled albumin
 Serum albumin
 Stool chymotrypsin
 Stool fat (smear)
 72 hrs stool fat
 Serum caroten
 D- Xylose test
 C14 triolein breath test
WBC- OP- Cl.diff. toxin - PH
 Stool
72 hrs fat (75-100 grams/24 hrs)
 Blood
CBC diff- ESR- Electrolytes - BUN
Creatinine – T3, T4 – gastrin- VIP
calcitonine - histamin
plain film (pancreatic calcification)CTscan
 Radiology

barium study ( upper GI- small, large
bowel)
biopsy and histology: celiac- GiardiaEndoscopy
crohn’s- lymphoma- eosinophilic GEenzyme assay – A beta- wolmanlymphangiectasia
MANAGEMENT
Rx. of underlying dx.
Nutritional support
Download
Related flashcards
Teeth

28 Cards

Teeth

29 Cards

Feces

26 Cards

Stomach

29 Cards

Create flashcards
Study collections