Download The Gastrointestinal System Overview - GI-Group-2010

The Gastrointestinal System
Structure, Function & Dysfunction
Gonzaga University
Nursing 523
July 30-31, 2010
Casey Fowler, Katarzyna Sedlaczek, and Stephanie Barss
Topics
1.
2.
3.
4.
Alterations of the GI Tract
Alterations of the Accessory Organs of Digestion
Cancer of the Digestive System
Alterations of Digestive Function in Children
Overview
For this module, there will be a brief overview of normal structure and function of the GI
system; however, most of the content will concern alterations of normal structure and
function. For more in depth information about normal structure and function of the GI
system, please refer to chapter 38 of your text book.
What is the digestive system?
The primary concern of the GI system is to ingest nutrients and fluids, digest and absorb
those nutrients and fluids, and to eliminate waste products. It is subdivided into two
sections: the GI tract and the accessory organs of digestion. The GI tract is comprised of
those organs that ingested nutrition and fluid flow through. It includes the mouth, the
esophagus, the stomach, the small and large intestines, the rectum, and the anus. The
accessory organs of digestion include the salivary glands, the liver, the gallbladder, and
the pancreas.
The Gastrointestinal Tract
Mouth
The mouth is the site of ingestion, and it is also where the process of digestion begins.
While in the mouth, the teeth grind food down and mix it with saliva. The tongue then
pushes the food toward the back of the and into the esophagus. The saliva contains αamylase which begins the process of breaking down carbohydrates. Once the food is
sufficiently mixed and ground down, the tongue presses the food together against the roof
of the mouth to form a bolus.
Esophagus
The esophagus is a hollow muscular tube that is approximately 25 cm long. Its primary
task is to transport nutrients and fluid from the mouth to the stomach via peristalsis. The
upper portion of the esophagus is composed of striated muscle, and it is under voluntary
control. The middle portion is a mix or striated and smooth muscle with less voluntary
control and the lower portion is composed of smooth muscle with no voluntary control.
As the food passes through the last portion of the esophagus it reaches the lower
esophageal sphincter which opens to allow the food passage into the stomach.
Stomach
The stomach is a hollow muscular organ that stores food while it is converted into a form
the body can use. It secrets gastric juices to break down nutrients (primarily proteins) into
smaller particles that the body can absorb. The stomach contracts to mix the gastric juices
with the chyme, which helps to insure more complete digestion. As this process comes to
an end, the stomach propels the chyme into the pyloris in preparation for entering the
duodenum. The stomach will only allow small amounts of the acidic chyme through the
pyloric sphincter at a time in order to allow the buffering enzymes in the duodenum to
neutralize the acid.
Small intestine
The small intestine is a 22 foot long hollow muscular organ, and it is the primary site of
absorption for nutrition and fluid. It is subdivided into three sections, the duodenum,
jejunum, and ileum. The duodenum is the primary site of mixture between the chyme and
digestive enzymes from the liver and the pancreas. These enzymes break down
carbohydrates, lipids, and portions. Subsequently, the jejunum and the ileum are the
primary sites for absorption of nutrients and fluids. The entire small intestine is lined with
small fingerlike projections called villi. These villi dramatically increase the absorptive
surface area of the small intestine so that it can absorb nutrition and fluids more
efficiently. As the chyme moves through the small intestine, it moves back and forth
allowing all of the chyme to contact the villi so that more nutrients can be absorbed. At
the end of the small intestine is the ileocecal valve which allows the chyme to pass from
the small intestine into the large intestine.
Colon (large intestine)
Is a 1.5m long hollow muscular organ composed of the cecum, the appendix, ascending,
transverse, descending, and sigmoid colon, the rectum, and the anus. The primary task of
the large intestine is to process and eliminate waste. When the chyme enters the cecum, it
is in a liquid form, but as it moves through the colon, the fluid is absorbed, leaving a solid
waste product behind. In assertion, as the chyme moves through the colon, the bacterial
flora digests nutrients that the body was unable to. The by product is that the bacteria
synthesize many essential vitamins which are subsequently absorbed by the colon. Once
the solidified chyme reaches the sigmoid colon, it waits to be empties into the rectum for
elimination. The sigmoid colon empties into the rectum once or twice daily. As the stool
stretches the rectum, it stimulates defecation. The stool is then eliminated through the
anus.
Accessory Organs of Digestion
Pancreas
The pancreas is considered to be an exocrine and an endocrine gland. Its exocrine
function is to secrete digestive enzymes (e.g., trypsin, chymotripsin, lipase and amylase)
into the duodenum to break down carbohydrates, fats, and portions. Its endocrine function
involves insulin and glucagon secretion.
Liver
The liver it the largest organ in the human body, and it has many functions that affect
digestion and metabolism. Its primary digestive function is to secrete bile into the
duodenum for the emulsification of fats. This process is essential, because without it,
absorbing fats would be impossible.
Gallbladder
The gallbladder is a small sack like organ attached to the liver’s right lobe. Its primary
function is to receive bile from the liver, concentrate it, and secrete it into the duodenum
as needed.
Review Materials
Readings
o Text: McCance et al (2010), chapters 38-40
o Review the articles listed under the Clinical Readings and General
Readings sections of the Read tab. There are a lot of PDFs here for you
with no expectation that you will read all of them; rather, add them to
your library of resources and read those you are not familiar with.

View
o Review the four PowerPoint presentations under the View section. These
presentations provide an outline for reviewing the content in the text
book. The presentations only cover chapters 39 and 40 as these are the
only chapters that discuss disease processes of the digestive system.
Please refer to chapter 38 in the text book for a review of normal digestive
structure and function.

Videos
o Overview of the digestive process
http://www.youtube.com/watch?v=Z7xKYNz9AS0
o Overview of GERD http://www.youtube.com/watch?v=7yHX4135kiM

Videos (continued)
o Overview of Hiatal Hernias
http://www.youtube.com/watch?v=yHGeNZXpIe0
o Overview of Gastritis http://www.youtube.com/watch?v=vVL9NJFh_kg
o Overview of Peptic Ulcer Disease
http://www.youtube.com/watch?v=3bhuiTRuJbE
Overview of Lactose Intolerance
http://www.youtube.com/watch?v=JbEYMaqJYoc
o Overview of Ulcerative Colitis
http://www.youtube.com/watch?v=HcSmVKGnGPE
o Overview of Crohn’s Disease
http://www.youtube.com/watch?v=8Y1epQtfdD4
o Overview of Diverticular Disease
http://www.youtube.com/watch?v=3xkq4VkWUO8
o Overview of appendicitis http://www.youtube.com/watch?v=GU84Th_ZKc
o Overview of Irritable Bowel Syndrome
http://www.youtube.com/watch?v=IqhBpHyBReI
o Overview of obesity http://www.youtube.com/watch?v=2675sU3xWto
o Overview of Anorexia Nervosa http://www.youtube.com/watch?v=Gu_i33X9-4
o Overview of Bulimia Nervosa
http://www.youtube.com/watch?v=NXm59j53SmA&feature=channel
o Overview of portal Hypertension
http://www.youtube.com/watch?v=pGA6KUgq7AI
o Overview of Hepatic Encephalopathy
http://www.youtube.com/watch?v=i4xb7ZMU4KE
o Overview of Jaundice http://www.youtube.com/watch?v=euetJ3Af8q0;
http://www.youtube.com/watch?v=N5gI8f1vebQ&feature=related;
http://www.youtube.com/watch?v=SygeRatR3aA&feature=related
o Overview of Hepatitis A
http://www.youtube.com/watch?v=FBUgcR85Eu0
o Overview of Hepatitis B
http://www.youtube.com/watch?v=6KSnZ4dOIRU&feature=related
o Overview of Hepatitis C
http://www.youtube.com/watch?v=kfIu9uQODgQ
o Overview of Hepatitis D
http://www.youtube.com/watch?v=4YFhXwUOF2s
o Overview of Hepatitis E
http://www.youtube.com/watch?v=8TAQk0FhzCA
o Overview of Hepatitis G
http://www.youtube.com/watch?v=dGBf2IfybHM
o Overview of fulminate hepatitis
http://www.youtube.com/watch?v=G5G9AnVhqhI
o Overview of Cirrhosis http://www.youtube.com/watch?v=dJl5pBNFZtc
o Overview of Cholelithiasis http://www.youtube.com/watch?v=KccMwsBfPA
o Overview or Cholecystitis
http://www.youtube.com/watch?v=5HKYL8KBC-c
o Overview of Pancreatitis
http://www.youtube.com/watch?v=iA7cwCexs6w&feature=related

Videos (continued)
o Overview of Liver Cancer
http://www.youtube.com/watch?v=cKQETTaaiJc
o Overview of Pancreatic Cancer
http://www.youtube.com/watch?v=6EvhkBUnxeQ
o Overview of Colon Cancer
http://www.youtube.com/watch?v=DABeD_X-jm4
o Overview of Esophageal Cancer
http://www.youtube.com/watch?v=ei4cOvFIqPY
o Overview of Oral Cancer
http://www.youtube.com/watch?v=HiTOTtN8jww
o Overview of Stomach Cancer
http://www.youtube.com/watch?v=CYE8I5O7tJ8&NR=1&feature=fvwp
o Overview of Cleft Lip/Palate
http://www.youtube.com/watch?v=_fY7erHvL2A
o Overview of Esophageal Artesia
http://www.youtube.com/watch?v=sNKOCM99zaU
o Overview of Pyloric Stenosis
http://www.youtube.com/watch?v=CNZ6MpWL634
o Overview of Intestinal Malrotation
http://www.youtube.com/watch?v=VUIl8C7m01A
o Overview of Congenital Aganglionic Megacolon
http://www.youtube.com/watch?v=L6h8IqOVm_I
o Overview of Intussusception
http://www.youtube.com/watch?v=iFzMzV_hCdc
o Overview of Cystic Fibrosis
http://www.youtube.com/watch?v=HUCzNRdT8EI
o Overview of Biliary Atresia
http://www.youtube.com/watch?v=AcwyzZgPdLs
Learning Objectives

Chapter 38: Structure and Function of the Digestive System
o Characterize the primary processes of digestion performed by the
gastrointestinal tract.
o Identify and describe the four layers of the digestive tract that are found
from the stomach to the anus.
o Identify the locations for the three gastrointestinal nerve plexuses.
o Describe the function of the mouth, taste buds, and teeth in the digestive
process.
o Identify the names and locations of the major salivary glands; describe
saliva.
o Compare the sympathetic and parasympathetic controls on salivation.
o Identify the location, structure, and function of the esophagus; describe
the two phases of swallowing.
o Define and describe peristalsis.
o Compare the functions of the upper and lower esophageal sphincters.
o Describe the structure and function of the stomach.
o Describe the action of gastrin, cholecystokinin, and secretin on gastric
motility.
o Identify factors contributing to gastric emptying.
o Identify and describe the cells and secretory products of the gastric
glands.
o Discuss the cephalic, gastric, and intestinal phases of gastric juice
secretion.
o Characterize the locations, connections, length, and specialized gross
structures of the three segments of the small intestine.
o Describe how the structures of the peritoneal membrane surround the
abdominal organs and form the peritoneal cavity.
o Relate the structure of plicae, villi, and microvilli to their functions in the
digestive process.
o Describe the digestion and absorption of water, electrolytes,
carbohydrates, proteins, fats, vitamins, and minerals
o Compare segmentation and peristalsis.
o Discuss the ileogastric, intestinointestinal and gastroileal reflexes.
o Characterize the locations, connections, length, and specialized gross
structures of the large intestine.
o Discuss the interactions between the stretch receptors of the rectum and
the reflex responses of the external and internal anal sphincters that
promote feces expulsion.
o Discuss the location, number, and function of the normal bacterial flora
throughout the gastrointestinal tract.
o Describe the location and functions of the liver.
o Diagram the functional unit of the liver, and discuss the formation and
secretion of bile.
o Describe the source, characteristics, and function of bile.
o Discuss the formation of bilirubin; compare unconjugated and conjugated
bilirubin and urobilinogen.
o Describe the role of the liver in the metabolism of fats, proteins, and
carbohydrates and metabolic detoxification.
o Describe the appearance, position, and function of the gallbladder in
relation to the liver.
o Identify the location and structure of the pancreas.
o Characterize the structure, function, and secretions of the exocrine
pancreas.
o Describe the alterations in laboratory tests indicative of liver dysfunction,
obstructive gallbladder disease, and pancreatic dysfunction.
o Describe the alterations in the digestive system associated with normal
aging.

Chapter 39: Alterations of Digestive Function
o Describe the physiologic mechanisms associated with anorexia, nausea,
retching, vomiting, and projectile vomiting.
o Explain changes in structure and function that lead to constipation,
diarrhea, and abdominal pain.
o Compare the causes of osmotic, secretory, and motility diarrhea.
o Define and describe the following terms used in identifying the
manifestations of gastrointestinal dysfunction: referred pain, hematemesis,
melena, and occult bleeding.
o Compare and contrast parietal and visceral abdominal pain.
o Compare causes of upper and lower gastrointestinal bleeding.
o Characterize the various disorders of digestive motility: dysphagia,
achalasia, gastroesophageal reflux, hiatal hernia, paraesophageal hiatal
hernia, pyloric obstruction, and intestinal obstruction.
o Relate the causes of gastroesophageal reflux to methods used to treat the
disorder.
o Differentiate between the pathogenesis and manifestations of acute and
chronic gastritis.
o Describe the predisposing factors and complications of peptic ulcer
disease.
o Define peptic ulcer disease; compare duodenal, gastric, stress, Curling,
and ischemic ulcers.
o Describe the common causes and pathophysiology of the following
postgastrectomy syndromes: dumping syndrome, alkaline reflux gastritis,
afferent loop obstruction, diarrhea, weight loss, and anemia.
o Compare maldigestion and malabsorption.
o Characterize and compare the pathophysiology and manifestations of
pancreatic insufficiency, lactase deficiency, and bile salt deficiency.
o Describe inflammatory bowel disease; describe the similarities and
differences between ulcerative colitis and Crohn disease.
o Describe diverticula; compare diverticulitis and diverticulosis.
o Relate the use of a high-fiber diet in the treatment of diverticular disease
to the etiologic factors for the condition.
o Describe the symptoms and manifestations associated with appendicitis.
o Discuss the blood supply to the stomach and intestines; relate mesenteric
venous thrombosis, acute occlusion of mesenteric artery blood flow, and
chronic mesenteric insufficiency.
o Characterize the disorders of nutrition: obesity, bulimia, anorexia nervosa,
and starvation.
o Interrelate the hormones and cytokines related to obesity.
o Describe starvation; discuss the cellular and metabolic alterations
occurring with short-term and long-term starvation.
o Describe the pathophysiologic changes associated with portal
hypertension.
o Discuss the major complications of portal hypertension: varices,
splenomegaly, ascites, and hepatic encephalopathy.
o Diagram the mechanisms of bilirubin formation, transport, and
elimination.
o Categorize and describe the complications of liver dysfunction; compare
prehepatic, hepatic, and posthepatic jaundice.
o Relate the pathophysiology and manifestations of hepatorenal syndrome
(HRS) to advanced liver disease.
o Compare hepatitis types A, B, C, D, E, and G in terms of incubation,
source, carrier status, and chronic disease development.
o Describe hepatic cirrhosis, and compare the various types: alcoholic,
biliary (primary and secondary), and postnecrotic.
o Compare and contrast cholelithiasis to cholecystitis.
o Describe the pathogenesis and systemic manifestations of pancreatitis.
o Discuss the risk factors, incidence, manifestations, treatment, morbidity,
and mortality of gastrointestinal tract tumors: esophageal, stomach, colon
and rectum, liver, gallbladder, and pancreas.

Chapter 40: Alterations of Digestive Function in Children (Optional)
o Describe the pathophysiology and treatment of cleft lip and palate.
o Describe the structural defects and resulting clinical manifestations of
esophageal atresia and tracheoesophageal fistula.
o Characterize the structural defect and pathophysiology associated with
pyloric stenosis.
o Describe the embryonic development and pathophysiology of intestinal
malrotation.
o Define and describe meconium.
o Characterize the obstruction present in a meconium ileus.
o Compare and contrast the pathophysiology and manifestations of the
following congenital obstructions of the intestinal tract: distal intestinal
obstruction syndrome, congenital aganglionic megacolon (Hirschsprung
disease), and anorectal malformations.
o Describe and identify common sites for intussusception.
o Discuss the rationale behind an infant’s increased susceptibility to
gastroesophageal reflux.
o Describe the pathophysiologic triad associated with cystic fibrosis.
o Relate the pathophysiology of cystic fibrosis to the common clinical
manifestations.
o Describe gluten-sensitive enteropathy (celiac disease).
o Compare and contrast kwashiorkor and marasmus.
o Discuss the multiple factors implicated in failure to thrive; compare
organic and nonorganic failure to thrive.
o Describe the emergent nature of necrotizing enterocolitis (NEC).
o Identify the causes and consequences of diarrhea in infants and children.
o Describe the dietary restrictions of children with primary lactose
intolerance.
o Discuss the common causes of physiologic jaundice of the newborn.
o Define biliary atresia, and discuss the damage sustained by the liver.
o Describe the pathophysiology and compare the incidence of hepatitis
types A, B, and C in children.
o Discuss the development of chronic hepatitis and cirrhosis in children.
o Compare and contrast extrahepatic (prehepatic) and intrahepatic portal
hypertension.
o Compare and contrast the three common metabolic disorders in children
producing liver damage: galactosemia, fructosemia, and Wilson disease.
Learning Activities
 Discuss
o Please respond individually one of the case study listed in the GI case
studies document. Think critically and ask questions. What would you
diagnose this patient with? Support your answer with evidence from the
study. What further evidence do you need to confirm your diagnosis?
How would you treat this patient? Please be sure to include references.
Please note that this module is only during July 30-31, 2010, so you have
two days to complete this assignment.

Reflection
o Please reflect on a difficult case you have experienced involving the GI
tract. Share your experience with the group, and share how what you have
learned in this module will affect your practice as an advanced practice
nurse.
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