Section 4C Flashcards
Is the diameter of the colon greater or smaller than that of the small intestine?
Greater
The fibers of the external muscular layer of colon are collected into what?
Longitudinal bands called teniae coli
Because of the teniae coli, the colon wall forms outpouchings between the teniae called what?
Haustra
Does the colon have villi similar to the Small Intestine?
No,
What 4 cell types reside in the large intestine crypts of lieberkuhn?
Absorptive Cells
Goblet Cells
Endocrine Cells
Regenerative Cells
4 Functions of the large intestine?
- Propulsion & Storage of unabsorbed material
- Place of residence for flora (bacteria)
- Absorption of small amounts of water and electrolytes
- Defecation
What is responsible for the slightly acidic nature of stools?
The organic acids generated by fermentation from intestinal flora
pH (5.0 - 7.0)
What leads to gas formation?
Fermentation of indigestible sugars in colon
Name 4 roles of the intestinal flora in the large intestine?
- Fermentation of undigested dietary fiber to generate fatty acids
- Creation of an environment that is inhospitable to pathogenic microorganisms and thereby preventing their colonization of the GI tract
- Metabolism of various compounds
- Creation of vitamin K, B12 and folic acid
Why is fermentation of undigestable fibers important to the colon?
They generate fatty acids which are a major nutritional source for the colon and have trophic effects to promote mucosal growth and development
What are the 4 mechanisms by which diarrhea can be caused?
- Increased osmotic load
- Increased secretion
- Inflamation
- Decreased absorption time
What is osmotic diarrhea?
Occurs when unabsorbable, water-soluble solutes remain in the bowel, where they retain water
What may cause osmotic diarrhea?
Sugar intolerance, including lactose intolerance caused by lactase deficiency, and with the use of poorly absorbed salts as laxatives or anatacids
Why does ingestion of large amounts of hexitol sugar substitutes cause osmotic diarrhea?
Their slow absorption and stimulation of rapid small-bowel motility.
What is secretory diarrhea?
Occurs when the small and large bowel secrete more electrolytes and water than they absorb.
Secretagogues in secretory diarrhea include what 4 things?
- Bacterial toxins
- Enteropathogenic viruses
- Bile acids
- Unabsorbed dietary fat
What is exudative diarrhea?
Occurs with several mucosal diseases that cause mucosal inflammation, ulceration, or tumefaction. The resultant outpouring of plasma, serum proteins, blood, and mucus increases fecal bulk and fluid content.
What causes decreased absorption time in diarrhea?
occurs when chyme is not in contact with an adequate absorptive surface of the GI tract for a long enough time so that too much water remains in the feces