ch 15 Flashcards
composition and formation of normal feces
100-200 g of fecal material passed each day
–> undigested food, intestinal bacteria, GI secretions, bile pigments
effect of abnormal intentinal water reabsorption on the consistency of feces
volume of fluid that exceeds absorption capacity leads to watery stool
three physiologic mechanisms that cause diarrhea
secretory, osmotic, and intestinal hypermotility
secretory vs osmotic diarrhea using fecal osmolality
secretory: increased intestinal secretion (within 10-20 mOsm)
osmotic: ingestion of osmotically active solute (exceeds 20 mOsm)
three causes of secretory and osmotic diarrhea
maldigestion vs malabsorption
maldigestion: inability to convert foodstuffs into absorbable substances
malabsorption: normal digestive ability but inadequate intestinal absorption
steatorrhea maldigestion diseases
pancreatitis, cystic fibrosis
steatorrhea malabsorption diseases
celiac disease
inflammatory vs noninflammatory acute diarrhea
noninflammatory: large volume of stool (nausea and vomiting)
–> stomach viruses (osmotic and secretory diarrhea
inflammatory: normal volume of stool (bloody)
–> secretory diarrhea (colonic invasion
pathogens associated with acute diarrhea
bacteria (e. coli, salmonella), viruses (noro, rota), or parasites (tapeworms)
diseases associated with chronic diarrhea
IBD (inflammatory bowel disease) –> crohns disease or celiac disease
inflammatory vs noninflammatory chronic diarrhea
inflammatory: bloody + watery, fecal WBC, osmotic malabsorption
noninflammatory: normal volume diarrhea
steatorrhea
fat content that exceeds 7g per day
–> looks pale, greasy, bulky and pasty
microscopic characteristics of normal feces
visual: normal brown feces
consistency: firm
form: tubular cylindrical
major causes of abnormal fecal color, consistency, and odor
red: blood
black: blood, iron, charcoal
hard: constipation
soft: increased fecal water
watery: diarrhea
narrow: bowel obstruction
small: constipation
bulky: steatorhea
qualitative assessment of fecal fat using microscopic examination
two slide qualitative procedure can be used to detect increased fat in feces using Sudan III, IV, or oil red O for natural fat triglycerides
–> second slide measures fat based on acidification (fats, fatty acids, and fatty acid salts
normal amount of fecal natural fate and increased amount of total fat
malabsorption
increased amount of neutral fat
maldigestion
5 causes of blood in feces
cancer, ulcers, hemorrhoids, bleeding gums, and drugs
small amount of blood in feces that is not visually apparent
occult blood
different indicators used on commercial slide tests for fecal occult blood
guaiac based tests: pseudoperoxidase; inexpensive
immunochemical tests: polyclonal Ab; high specificity
collection techniques and requirements
can be collected in any clean, nonbreakable container
