NURS 611 :Exam 4
COMPLETE & UPDATED
Study Guide – Part 2
Week 14
Chapter 41: Structure & Function of the Digestive System
1. The Gastrointestinal Tract
a. Major functions of the gastrointestinal tract are the mechanical and chemical
breakdown of food and the absorption of digested nutrients
b. The walls of the gastrointestinal tract have several layers: mucosa, muscularis mucosa,
submucosa, muscularis (circular muscle and longitudinal muscle), and serosa (adventitia
in the esophagus).
c. Except for swallowing and defecation, which are controlled voluntarily, the functions of
the gastrointestinal tract are controlled by extrinsic autonomic nerves (vagus,
parasympathetic splanchnic, and sympathetic nerves) and intrinsic autonomic nerves
(enteric nervous system) and intestinal hormones
d. Intrinsic factor (IF), a mucoprotein produced by parietal cells, combines with vitamin
B12 in the stomach. It is required for the absorption of vitamin B12 by the ileum.
Atrophic gastritis and failure to absorb vitamin B12 result in pernicious anemia
2. Accessory Organs of Digestion
a. Liver
i. The liver is the largest organ in the body. It has digestive, metabolic,
hematologic, vascular, and immunologic functions.
ii. The liver is divided into the right and left lobes and is supported by the
falciform, round, and coronary ligaments.
b. Gallbladder
i. The gallbladder is a saclike organ located in the inferior surface of the liver. The
gallbladder stores bile between meals and ejects it when chyme enters the
duodenum.
ii. Stimulated by cholecystokinin, the gallbladder contracts and forces bile through
the cystic duct and into the common bile duct. The sphincter of Oddi relaxes,
enabling bile to flow through the major duodenal papilla into the duodenum.
c. Exocrine Pancreas
i. The pancreas is a gland located behind the stomach. The endocrine pancreas
produces hormones (glucagon and insulin) that facilitate the formation and
cellular uptake of glucose. The exocrine pancreas secretes an alkaline solution
and the enzymes (trypsin, chymotrypsin, carboxypeptidase, α-amylase, lipase)
that digest proteins, carbohydrates, and fats.
ii. Secretin stimulates pancreatic secretion of alkaline fluid, and cholecystokinin
and ACh stimulate secretion of enzymes. Pancreatic secretions originate in acini
and ducts of the pancreas and empty into the duodenum through the common
bile duct or an accessory duct that opens directly into the duodenum.
3. Tests of Digestive Function
, a. Gastrointestinal Tract
i. Numerous diagnostic tests can evaluate structure and function (digestion,
secretion, absorption) of the gastrointestinal tract. Radiographs and scans are
most commonly used to evaluate structure, in addition to direct observation by
endoscopy. Gastric and stool analysis and blood studies provide important
information about digestion, absorption, and secretion.
b. Liver
i. Plasma chemistry levels and imaging procedures are commonly used to
diagnose alterations in liver function. Of particular importance are the enzymes
LDH, AST, and ALT. Plasma bilirubin levels reflect alterations in bilirubin and bile
metabolism, and prothrombin times are prolonged in hepatitis and chronic liver
disease.
c. Gallbladder
i. Obstructive diseases of the gallbladder are evident by elevated serum bilirubin
levels, elevated urine urobilinogen levels, and increased stool fat. The serum
leukocyte levels become elevated with inflammation of the gallbladder.
d. Exocrine Pancreas
i. The most significant indicators of pancreatic dysfunction are serum amylase and
stool fat. Both values are increased with pathology of the pancreas.
4. Aging and the GI system
a. Advancing age is often associated with the loss or deterioration of teeth, diminished
senses of taste and smell, and diminished salivary secretions, all of which may make
eating difficult and reduce appetite.
b. Aging reduces gastric motility and secretions, particularly of hydrochloric acid. These
changes slow gastric digestion and emptying.
c. Intestinal motility and absorption of carbohydrates, proteins, fats, and minerals
decrease with age.
d. Efficiency of drug and alcohol metabolism decreases with age and can be related to
decreased liver perfusion and decreased liver enzymes."
Chapter 42: Alterations of Digestive Function
1. Disorders of the GI tract
a. Clinical manifestations of Gastrointestinal Dysfunction
i. Diarrhea
1. What are the different types of diarrhea?
ii. GI bleeding
1. Figure 42.1, pathophysiology of GI bleeding
b. Disorders of Motility
i. Dysphagia
ii. GERD
1. Reflux of acid and pepsin or bile salts from the stomach to the
esophagitis