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Nursing Assessment:
Gastrointestinal System
Chapter 39 Overview
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Gastro intestinal system
• Main function is to supply nutrients to body
cells.
• This is accomplished by the processes :
ingestion ( taking in food), digestion ( breaking
down of food), and absorption ( transfer of
food product into circulation).
• Elimination is the process of excreting the
waste products of digestion.
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Components of GI tract
• Mouth , esophagus, stomach, small intestines,
large intestines, rectum and anus.
• Associated organs are: the liver, pancreas and
the gall bladder.
• Factors outside GI tract that can influence its
functioning: psychological and emotional
factors such as stress and anxiety.
• Stress may be manifested by anorexia, nausea,
epigastric and abd pain or diarrhea.
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Fig. 39-1. Location of organs of the gastrointestinal system.
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Structures and Functions of
Gastrointestinal System
Fig. 39-3. Anatomic locations of the large intestine.
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GI system
• GI systems should never be attributed solely to
psychological factors.
• Physiological factors that affect the GI tract :
the dietary intake, alcohol, caffeine, smoking,
and poor sleep.
• Peptic ulcer disease and ulcerative colitis may
be aggravated by stress.
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Structures and functions of the GI
system
• GI system extends from mouth to anus and is
about 30 feet long
• The entire tract is composed of four common
layers : mucosa, submucosa, muscle and
serosa.
• GI tract is innervated by the autonomic
nervous system : sympathetic and
parasympathetic systems
• Sensory information is relayed by both
sympathetic and parasympathetic system
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GI system
• Peristalsis is increased by parasympathetic
system and decreased by sympathetic system
• GI tract also has its own nervous system enteric
( or intrinsic) : has the ability to control
movement and secretion of the GI tract
• GI tract and its accessory organs receive about
25% to 30% of the cardiac output.
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Circulatory system of the GI
system
• Portal vein : venous blood from the GI tract
empties in to portal vein, which then perfuses
the liver
• Splanchnic artery : upper portion of the GI tract
receives blood from the splanchnic artery
• Small intestines receives its blood supply from
branches of the hepatic and superior
mesenteric arteries
• Large intestines receives its blood supply from
the masenteric artery
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Structures and Functions of
Gastrointestinal System
Fig. 39-5. Microscopic structure of liver lobule.
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Structures and Functions of
Gastrointestinal System
• Ingestion and Propulsion of Food
• Mouth
• Pharynx
• Esophagus
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GI system
• Two types of movements of the GI tract :
mixing ( segmentation ) and propulsion (
peristalsis)
• The secretions of the GI system consists of
enzymes and hormones for digestion, mucus
for lubrication, and water and electrolytes.
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Ingestion and propulsion of food
• Ingestion is the intake of food.
• Intake of food depends on the appetite
• Appetite center is located in the
hypothalamus: stimulated by hypoglycemia,
an empty stomach, decreased in body
temperature, and input from higher brain
centers.
• The sight, smell and taste of food usually
stimulate appetite.
•
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Ingestion cont ..
• Appetite may be inhibited by stomach
distention, illness, hyperglycemia, nausea,
vomiting and drugs( amphetamines).
• Deglutition or swallowing is the mechanical
component of ingestion. ex mouth, pharynx,
and esophagus
• Mouth: taste receptors( in the tongue), salivary
glands ( parotid, submaxillary, and sublingual
glands)
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GI tract cont…
• Saliva : one liter of saliva is produced each day
• Saliva consists of water, protein, mucin,
inorganic salts, and salivary amylase.
• Saliva: lubrication of food, and prevention of
bacterial overgrowth
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GI tract
• Esophagus : hollow muscular tube, moves food
to stomach by peristalsis
• There are two sphincters : upper and lower
esophageal sphincters ( upper in the proximal
and lower in the distal end of the esophagus)
• LES remains contracted except during
swallowing, belching and vomiting
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Structures and Functions of
Gastrointestinal System
Fig. 39-2. Parts of the stomach.
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Digestion and Absorption
• Mouth : digestion begins, mechanical and
chemical digestion, amylase breaks starches to
maltose
• Stomach: store and mix food with gastric
secretions, only absorbs small amount of
water, alcohol, electrolytes and drugs.
• LES and the pyloric sphincters guards the
entrants and the exit from the stomach
• Secretions of stomach: pepsinogen which
digests proteins, HCL activate pepsinogen to
more active pepsin, lipase which digests fats
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S/P Gastractomy
• Patient at higher risk for vitamin B12
deficiency
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Structures and Functions of
Gastrointestinal System
Fig. 39-6. Bilirubin metabolism and conjugation.
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Digestion and Absorption
• Small intestines: two primary functions are
digestion and absorption, extends from
pylorus to the ileocecal valve, ileocecal valve
prevents backing up from the large intestines
• Functional units of the small intestines are villi.
They increase the surface area for absorption,
secretes mucus and digestive enzymes.
• Secretions of the small intestines:
enterokinase, amylase, peptidase,
aminopeptidase, maltase, sucrase, lactase,
and lipase
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Digestion
• STOMACH: pepsinogen + HCL
pepsin (
more active form ) + protein
Amino acids
• There is minimal digestion of starches and fats
in the stomach
• Small intestines: carbs into monosaccharides,
fats to glycerol and fatty acids, and proteins to
amino acids.
• Acidic nature of the chyme or the food that
enters the duodenum is neutralized by
pacreatic secretion of bicarbonate.
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Digestion
• Cholesystokinin : produced by duodenum,
contracts the gall bladder and relaxes the
sphincter of odi which allows the bile to flow to
the duodenum.
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Elimination
• Large intestines: hollow, muscular tube about
5 to 6 feet long.
• Parts of large intestines: cecum and appendix,
the colon, the rectum and anus
• Most important part of the large intestine is
the absorption of water and electrolytes
• Nursing implications of colon resection and
ileus: dehydration and electrolyte imbalance.
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Structures and Functions of
Gastrointestinal System
Fig. 39-3. Anatomic locations of the large intestine.
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Elimination
• Feces are composed of 75 % water, bacteria,
minerals, and bile pigments.
• Bacteria in the colon also synthasize vitamine
K and some of the B vitamins
• Defecation : reflex action, involuntary and
voluntary, acceptable environment is usually
necessary, if defecation is suppressed constipation and impaction, defecation can be
facilitated by valsalva maneuver.
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Elimination cont..
• Treatments for constipation :
increase fluid intake, increase fiber,
decrease laxative use, encourage
defecation after eating breakfast as
reflexes are most active after the
first daily meal. And routine.
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Elimination
• Constipation is common among older adults:
slower peristalsis, inactivity, decreased dietary
fiber, decreased fluid intake, depression and
laxative abuse.
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Liver, billiary tract and pancreas
• Liver : largest organ in the body and is located
in the right epigastric region, blood supply by
celiac artery and the portal vein,
• Function of the liver : manufacture, storage,
transformation and excretion
• Excretion of bilirubin which is derived from the
breakdown of hemoglobin
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Structures and Functions of
Gastrointestinal System
Fig. 39-4. Gross structure of the liver, gallbladder,
pancreas, and duct system.
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Gerontologic considerations
Effects of aging on the GI system
• Xerostomia : decreased saliva production, may
associate with difficulty swallowing and
dysphagia
• Taste buds decreased, sense of smell
decreased and may lead to decreased appetite.
• Delayed emptying, and decreased HCL leads to
infections
• Incompetent esophageal sphincter lead to
GERD
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Structures and Functions of
Gastrointestinal System
Table 39-2. Phases of Gastric Secretion
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Gerontologic Considerations:
Effects of Aging on Gastrointestinal System
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Diagnostic Studies of
Gastrointestinal System
• Radiologic Studies
• Upper gastrointestinal series
• Lower gastrointestinal series
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Diagnostic Studies of
Gastrointestinal System
Fig. 39-10. Barium enema x-ray showing
the large intestine.
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Diagnostic Studies of
Gastrointestinal System
Fig. 39-11. Ultrasound of gallbladder
showing multiple gallstones.
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Diagnostic Studies of
Gastrointestinal System
• Radiologic Studies, continued
• Virtual colonoscopy
• Endoscopy ( EGD)
These studies require patients to be
on golytely to clear bowels
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Diagnostic Studies of
Gastrointestinal System
Fig. 39-12. Ileocecal junction. A, Illustration showing the ileocecal junction and the
ileocecal fold. B, Endoscopic image of the ileocecal fold.
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Diagnostic Studies of
Gastrointestinal System
Fig. 39-13. Capsule endoscopy. A, The video capsule has its own camera and light source. After it is
swallowed, it travels through the GI tract and allows visualization of the small intestine. It sends
messages to a monitoring device that is worn on a waist belt (B). During the 8-hour examination, the
patient is free to move about. After the test, the images are viewed on a video monitor.
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Diagnostic Studies of
Gastrointestinal System
• Liver Biopsy ; patient is place on the right
side to prevent bleeding.
• Liver Function Studies
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