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
Factors that decrease contact time of chyme with intestine
- Small or large-bowel resection
- Gastric resection
- Vagotomy
- surgical bypass of intestinal segments
- drugs that speed transit time by stimulating intestinal smooth muscle
What is constipation?
the infrequent passage of stools. It is difficult to define since what is considered normal for one person is different than another. Problem increases with age.
7 common causes of constipation
- failure to respond to the urge to defecate
- Inadequate fiber in diet
- Inadequate fluid intake
- weakness of the abdominal muscles
- Inactivity and bed rest
- Pregnancy
- hemorrhoids
What is Irritable bowel syndrome?
Used to describe a functional GI disorder characterized by a variable combination of chronic and recurrent intestinal symptoms
IBS tends to result from what?
Dysregulation of intestinal motor and sensory functions modulated by the CNS
Are men or women more affected by IBS?
Women.
What is used to diagnose IBS
It lacks anatomic or physiologic markers, so it is based on signs and symptoms of abdominal pain or discomfort, bloating, constipation, diarrhea, or an alteration between both
What is inflammatory bowel disease?
A term used to designate two related inflammatory intestinal disorders: Crohn disease and Ulcerative colitis
What is Diverticulosis?
A condition in which the mucosal layer of the colon herniates through the muscularis layer.
Where in the colon does diverticulosis occur normally?
In the sigmoid
What causes diverticulosis?
high intraluminal pressure on areas of weakness in the bowel wall
What is the most common complaints of diverticulitis?
Pain in the lower left quadrant, accompanied by nausea and vomiting, tenderness in the lower left quadrant, a slight fever, and an elevated white blood cell count
What are the complications of diverticulitis?
Perforation with peritonitis, hemorrhage, and bowel obstruction
Where is pain in acute appendicitis?
Seen on lower right quadrant, fever, rebound tenderness
When can peritonitis occur in association with acute appendicitis?
If swollen appendix bursts before surgery. If this occurs, must be treated with antibiotics
What are the 4 major mechanical causes of intestinal obstruction?
- Herniation of a segment in the umbilical or inguinal regions
- Adhesion between loops of intestine
- Volvulus
- Intussusception
What is the valsalva maneuver?
To expel feces by using muscles of rectum, we voluntarily close the glottis and contract our diaphragm and abdominal muscles.
What type of reflex causes the walls of the sigmoid colon and rectum to contract and internal anal sphincter to relax?
Parasympathetic reflex
What can cause GI tract bleeding
- disease or trauma to GI structures
- Blood vessel abnormalities
- Disorders in blood clotting
What is hematemesis?
Refers to blood in the vomitus
Why might the hematemesis have a “coffee-ground” appearance?
Because of the action of the digestive enzymes
Bright red blood usually indicates what?
Bleeding is from the lower bowel
When blood coats the stool, what is occuring?
Bleeding hemorrhoids
Melena or black stools indicate what?
The source of bleeding is above the level of the ileocecal valve, although this is not always the case
Ocult, or hidden, blood can be detected how?
By chemical means only
What is one of the most common cancers in the western world?
Adenocarcinoma of the colon and rectum
When was the peak incidence of colon cancer?
6th and 7th decades
4 Predisopsing factors to colon cancer
- Polyps
- Long-Standing UC
- Genetic factors
- Low fiber, high animal fat diet
