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Nurs3100 Aging and the GI System
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Nurs3100 Aging and the GI SystemThe changes in the GI system that are associated with aging are dependent upon a person’s health
status, genetics, and environmental factors. Some changes can begin before the age of 50. As we
age, we lose tooth enamel and dentin, which increases the risk for developing cavities.
Periodontal disease, gum recession and osteoporosis can cause one to lose teeth. The sense of
smell decreases as does the ability to taste secondary to a loss of taste buds. This leads to a
reduced appetite in the elderly. Esophageal motility decreases with age and may lead to GERD.
Gastric motility, gastric secretions and blood flow decreases with age which leads to an
increased risk of injury to the mucosal lining. A decreased production in intrinsic factor is also
noted as we age which may lead to B12 deficiency and pernicious anemia. Ileal villi become
broader and shorter. Degeneration of the enteric nervous system neurons decreases intestinal
absorption, motility, blood flow and impairs nutrient absorption. Nutrients are absorbed more
slowly and in lesser amounts.
The liver is not able to regenerate as fast in the elderly. Hepatic blood flow decreases with age as
does the enzymatic activity both of which decreases drug metabolism. LFTs remain normal in
the elderly and an elevation is a sign of a disorder and not a result of aging. The pancreas
experiences some age-related fibrosis, fatty acid deposits and atrophy. The beta cells’ function
declines as well as we age.
Disorders of the Gastrointestinal System
Having a familiarity with the manifestations of GI Disorders is needed to help you as a
practitioner to accurately diagnose and manage your patients.
An upper gastrointestinal bleed by definition is any source of bleeding which occurs in the
esophagus, stomach or the duodenum. It is characterized by frank, bright red or “coffee ground”
(affected by the stomach) emesis. It is commonly caused by bleeding varices (varicose veins) in
the esophagus or stomach, peptic ulcers, gastritis, or a Mallory-Weiss tear (tearing of the
esophagus from the stomach). A lower gastrointestinal bleed is characterized by any source of
bleeding in the jejunum, ileum, colon, or rectum. It can be caused by inflammatory bowel
disease, cancer, diverticula or hemorrhoids. An upper or lower GI bleed, if left untreated or if it
is severe, may result in a shock. In this case the person would experience clinical manifestations
consistent with shock (decreased cardiac output, hypotension, acute renal failure, tachycardia,
anemia). An occult GI bleed is one that is not visible and results in iron deficiency. This is the
type of bleed we commonly associate with colon cancer. Hence the purpose for testing stools for
occult blood. Blood loss of 1000ml or greater will cause hypotension, tachycardia and if severe
enough may lead to hypovolemic shock.
Hematemesis is bright red, bloody emesis and is an indicator of an upper GI bleed. Usually this
type of bleed requires emergent intervention. Coffee ground emesis is emesis which looks like
used coffee grounds. This is indicative of an upper GI bleed but unlike hematemesis, it is not
necessarily an emergent issue. Melena is said to be present when a person’s stool is black and
tarry. It is an indicator of an upper GI bleed. Hematochezia is the presence of bright red blood in
,the stools and the presence of hematochezia suggests that the bleed is in the lower GI tract,
usually in the rectum, sigmoid colon or the descending colon.
Diarrhea is characterized by loose, watery stools. Acute diarrhea is defined as the presence of 3
loose stools that develops within 24 hours and lasts no longer than 14 days. Diarrhea which lasts
14-30 days is termed persistent diarrhea and chronic diarrhea is present for longer than 30 days.
Diarrhea may also be classified by the mechanism which causes it. Osmotic diarrhea is caused by
the presence of a nonabsorbable substance in the intestines. This pulls water by osmosis into the
intestinal lumen and results in large volume diarrhea. This is how the laxatives mag citrate,
lactulose and MiraLAX work. Excessive ingestion of nonabsorbable sugars can cause this type
of diarrhea. Other causes include tube feedings, dumping syndrome, malabsorption, pancreatic
enzyme deficiency, bile salt deficiency, small intestine bacterial overgrowth, or celiac disease.
Secretory diarrhea results in large volume losses secondary to infectious causes such as the
rotavirus, bacterial enterotoxins, or C-diff. These infections trigger enteroendocrine cells to
secrete 5HT and the activation of afferent neurons that stimulate submucosal secretomotor
neurons and alter sodium chloride transport resulting in decreased water 2 absorption. Motility
diarrhea is AKA as short bowel syndrome and results from the resection of the small intestine or
a surgical bypass of the small intestine or a portion of it, IBS, diabetic neuropathy,
hyperthyroidism, and laxative abuse. Complications of diarrhea may include dehydration,
electrolyte imbalances, metabolic acidosis, weight loss, and malabsorption. Fatty stools are
common in malabsorption syndromes as is bloating. Most infectious diarrhea usually lasts less
than 2 weeks. Fever, cramping and bloody stools may be seen in chronic diarrhea and are caused
by inflammatory bowel disease or dysentery.
Let us review some diagnostic tests specific to the GI tract.
Liver Function Tests (LFTs) are helpful with identifying hepatic injury and assessing the liver’s
synthetic function. Some tests as you will see are a measure of hepatic injury, and other tests tell
us about the liver’s synthetic function. Tests to measure injury and function include:
• AST (aspartate aminotransferase) is an intracellular protein which regulates metabolism. It is
a marker of hepatic injury. When it is elevated it indicates that there is hepatocellular injury
occurring. It does not tell you what is causing the injury, only that the injury is happening.
• ALT (alanine aminotransferase, SGPT) is also an intracellular enzyme which helps to
regulate metabolism and a marker of hepatocellular injury.
• ALP (alkaline phosphate) is an intracellular enzyme found in bone cells, liver, the intestines
and placenta. Elevations are seen in pregnant women, bone and liver disease, and obstruction of
the biliary tract.
• GGT (gamma-glutamyl transferase) is an enzyme that helps with transmembrane transports
of amino acids. Elevations are seen in obstruction of the biliary tract.
, • Albumin is a plasma protein which is produced by the liver. It is a marker of the liver’s
synthetic function, its ability to produce albumin. A decreased level of albumin may
indicate liver failure or malnutrition.
• Bilirubin comes from the degradation of heme (iron) in RBCs. A total bilirubin is the
measurement of direct and indirect bilirubin. Direct (conjugated) bilirubin is that bilirubin which
has undergone conjugation by the liver and when it is elevated indicates a biliary tract
obstruction. Indirect bilirubin (unconjugated) is that bilirubin which has not been processed by
the liver yet, and an elevation may be seen due to RBC hemolysis (hemolytic anemia) or in
hepatocellular damage.
Disorders of the Gastrointestinal
Tract Intestinal Obstruction
Intestinal obstruction is caused by any condition which prevents the forward movement of
chyme. They may be in the small or large intestine but are more common in the small intestine
because its lumen is narrower. A simple obstruction is caused by a mechanical blockage of the
lumen without impairing perfusion and is most commonly caused by adhesions. A strangulated
obstruction is one which impairs perfusion and if left untreated will lead to necrosis and
perforation. A paralytic ileus results from a failure in motility that occurs after abdominal or
intestinal surgery, from acute pancreatitis or hypokalemia.
Opioid use, anesthesia, local inflammatory reactions and an overactive sympathetic nervous
system also contribute to the development of a post-operative ileus. Other bowl obstruction
classifications include:
• Herniation is said to be present when the intestines protrude through an area of weakened
abdominal wall muscle or into the inguinal canal.
• Intussusception is characterized by a telescoping of the intestines into another portion of the
intestines. This causes a strangulated obstruction. This is more common in infants around the
ages 10-15 months.
• Torsion occurs when the intestines twist and occlude blood flow. This is most commonly
associated with adhesions in the small bowel. Occurs most often in the large intestine in
the elderly.
• Tumor growth particular secondary to colon cancer may cause an obstruction.
• Fibrous adhesions occur most commonly on the small bowel. They develop secondary to
peritoneal irritation from surgery or trauma, adhere to the small bowel and cause traction
and obstruction.
• Acute obstruction is of sudden onset and usually occurs from torsion, intussusception or
herniation.
• Chronic obstruction has a slow, protracted onset and occurs secondary to tumors or strictures.
• A partial obstruction only blocks part of the intestinal lumen.
• A complete obstruction blocks the entire lumen of the intestine.
Pathophysiology of Intestinal obstruction
The pathological consequences of an intestinal obstruction are directly related to the location, the
degree of the obstruction and the presence or absence of impaired perfusion. A small bowl
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