43: Assessment: Gastrointestinal System
Structures and Functions of Gastrointestinal System
The GI tract is essentially a tube composed of 4 layers. From the inside to the outside
(1) Mucosa lining
(2) Submucosa connective tissue, which contains glands, blood vessels, and lymph nodes;
(3) Muscle (There are 3 smooth muscle layers: the oblique (inner) layer, circular (middle) layer,
and longitudinal (outer) layer.)
(4) Serosa.
MSMS…my sis my sis
GI Nervous system…
● The parasympathetic (cholinergic) system is mainly excitatory. The sympathetic
(adrenergic) system is mainly inhibitory. For example…
● parasympathetic stimulation increases peristalsis,
● sympathetic stimulation decreases it.
The GI tract has its own nervous system: the enteric nervous system (ENS) or intrinsic
nervous system.
● ENS is composed of 2 networks:
(1) Meissner plexus in the submucosa: The submucosal plexus controls secretion and is
involved in many sensory functions. (Meissner plexus…Messyyyyyy plexus because is controls
messy secretions and senses)
(2) Auerbach (myenteric) plexus between the muscle layers :myenteric plexus is the major
nerve supply to the GI tract and controls GI movements. ( myenteric plexus…Auerbach gets on
MY nerves…because auerbach myenteric is a never supply to GI track)
The main function of the GI system
supply nutrients to body cells.
…This is accomplished through the processes of
(1) ingestion (taking in food)
(2) digestion (breaking down food)
(3) absorption (transferring food products into circulation).
Elimination is the process of excreting the waste products of digestion.
Ingestion
-the intake of food and out appetite influences how much we eat
-involves the mouth, pharynx, and esophagus
-our appetite center is in our hypothalamus
-Deglutition, or swallowing, is the mechanical portion of ingestion. The organs involved in
deglutition are the mouth, pharynx, and esophagus.
Factors that stimulate appetite
● hypoglycemia
● an empty stomach
● decrease in body temperature
● The hormone ghrelin released from the stomach mucosa plays a role in appetite
stimulation.
Factors that inhibit appetite
● Hormone Leptin
● Stomach distention
● illness (especially accompanied by fever)
● Hyperglycemia
● nausea and vomiting, and certain drugs (e.g., amphetamines) inhibit appetite.
Digestion and absorption
Digestion is the physical and chemical breakdown of food into absorbable substances. The
timely movement of food through the GI tract and the secretion of specific enzymes promote
digestion. These enzymes break down food to particles of appropriate size for absorption
The process of digestion begins in the mouth, where food is chewed, mechanically broken
down, and mixed with saliva. Saliva helps us swallow by lubricating food. Saliva contains
amylase, which breaks down starches to maltose. Chewing and the sight, smell, thought, and
taste of food stimulate the release of saliva. A person makes about 1 L of saliva each day. After
swallowing, food moves through the esophagus to the stomach. No digestion or absorption
occurs in the esophagus.
-the small intestine takes nutrients from the gut lumen to the bloodstream.it is the longest
portion of the GI tract
Elimination(Large intestine)
-Peristalsis is most active after first meal
-The large intestine is a hollow, muscular tube around 5 to 6 ft (1.5 to 1.8 m) long and 2 in (5 cm)
in diameter.
-The most important functions of the large intestine are water and electrolyte absorption.
-The large intestine also forms feces and serves as a reservoir for the fecal mass until defecation
occurs.
-The large intestine secretes mucus, which acts as a lubricant and protects the mucosa.
The colon is the largest part of the large intestines…Microorganisms in the colon contribute to
digestion by
(1) producing vitamin K and some B vitamins and
(2) breaking down proteins that are not digested or absorbed in the small intestine into amino
acids.
Liver, Biliary Tract, and Pancreas
The liver performs many functions and is essential for life. It has metabolic, secretory,
vascular, and storage functions
VALSALVA MANEUVER-bearing down
And leads to decreased HR, CO and BP
-this is contraindicated in head injuries and eye surgery because you dont wanna add any
extra pressure also heart issues, hemorrhoids, abdominal surgery, and liver cirrhosis
w/portal hypertension
For GI bleeds they are on fall risk because they are loosing blood and they bear down
…double homicide
Liver functions
Function
Description
Metabolic Functions
Blood clotting
Synthesis of prothrombin (factor I), fibrinogen (factor II) and factors V, VII, IX, and X.
Carbohydrate
metabolism
Performs glycogenesis (conversion of glucose to glycogen), glycogenolysis (process of breaking
down glycogen to glucose), gluconeogenesis (formation of glucose from amino acids and fatty
acids).
Detoxification
Inactivates drugs and harmful substances and excretes their breakdown products.
Fat metabolism
Synthesis of lipoproteins, breakdown of triglycerides into fatty acids and glycerol, formation of
ketone bodies, synthesis of fatty acids from amino acids and glucose, synthesis and breakdown of
cholesterol.
Protein metabolism
Synthesis of nonessential amino acids, synthesis of plasma proteins (except gamma globulin),
synthesis of clotting factors. Bacteria in colon deaminate amino acids to form ammonia (NH3),
which is then changed to urea (NH4).
Secretory Functions
Bile production
Formation of bile, which contains bile salts, bile pigments (mainly bilirubin), and cholesterol.
Bilirubin
Conjugation and secretion of bilirubin.
Vascular Functions
Blood filtration
Breakdown of old RBCs, WBCs, bacteria, and other particles. Breakdown of hemoglobin from old
RBCs to bilirubin and biliverdin.
Blood reservoir
Serves as temporary storage for blood within general circulation.
Storage Functions
Storage
Stores glucose in form of glycogen; vitamins, including fat-soluble (A, D, E, K) and water-soluble
(B1, B2, cobalamin, folic acid); fatty acids; minerals (iron, copper); and amino acids in form of
albumin and β-globulins.
Biliary tract
-The biliary tract consists of the gallbladder and ducts that connect the liver, gallbladder, and
duodenum. The gallbladder is a pear-shaped sac found below the liver. Its function is to
concentrate and store bile. It holds around 45 mL of bile. The presence of fat in the upper
duodenum triggers the release of cholecystokinin, which causes the gallbladder to contract and
release bile.
Pancreas
-The pancreas is a long, slender gland lying behind the stomach and in front of the first and
second lumbar vertebrae. It consists of a head, body, and tail
- The exocrine function of the pancreas contributes to digestion. Theendocrine function occurs
in the islets of Langerhans, whose cells secrete insulin, cells secrete glucagon, and cells secrete
somatostatin.
Gerontologic Considerations: Effects of Aging on GI System
● Aging changes the functional ability of the GI system.
● Many factors can lead to a decrease in appetite and make eating less pleasurable,
including caries and periodontal disease, fewer taste buds, a lessened sense of smell, and
decreased saliva production.
● The liver size decreases after 50 years of age, but liver function tests stay within normal
ranges.
● The ability to metabolize drugs and hormones decreases.
● Risk for decreased food intake and ability to obtai
Structures Located in Abdominal Regions
Right Upper Quadrant
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• Liver and gallbladder
• Pylorus
• Duodenum
• Head of pancreas
• Right adrenal gland
• Portion of right kidney
• Hepatic flexure of colon
• Portion of ascending and
transverse colon
Left Upper Quadrant
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• Left lobe of liver
• Spleen
• Stomach
• Body of pancreas
• Left adrenal gland
• Portion of left kidney
• Splenic flexure of
colon
• Portion of transverse
and descending colon
Right Lower Quadrant
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• Lower pole of
right kidney
• Cecum and
appendix
• Portion of
ascending colon
• Bladder (if
distended)
• Right ovary and
fallopian tube
• Uterus (if
enlarged)
• Right spermatic
cord
• Right ureter
Left Lower Quadrant
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• Lower pole of
left kidney
• Sigmoid
flexure
• Part of
descending
colon
• Bladder (if
distended)
• Left ovary and
fallopian tube
• Uterus (if
enlarged)
• Left spermatic
cord
• Left ureter
Normal assessment of GI system
Mouth
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• Moist and pink lips
• Pink and moist buccal mucosa and gingivae without plaques or lesions
• Teeth in good repair
• Protrusion of tongue in midline without deviation or twitches
• Pink uvula (in midline), soft palate, tonsils, and posterior pharynx
• Swallows smoothly without coughing or gagging
Abdomen
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• Flat without masses or scars. No bruises
• Bowel sounds in all quadrants
• No abdominal tenderness; nonpalpable liver and spleen
• Liver 10 cm in right midclavicular line ( The liver edge should feel firm, sharp, and smooth)
• Generalized tympany
Anus
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• Absence of lesions, fissures, and hemorrhoids
• Good sphincter tone
• Rectal walls smooth and soft
• No masses
• Stool soft, brown, and heme negative
Look at table 43.10 for abnormal findings
Diagnostic Studies- table 43.11
DIAGNOSTIC STUDIES OF GASTROINTESTINAL SYSTEM
● Many of the diagnostic procedures of the GI system require measures
to cleanse the
GI tract, as well as the use of a contrast medium or a radiopaque tracer.
● An upper GI series with small bowel follow through provides visualization of the
esophagus, stomach, and small intestine.
● A lower GI series (barium enema) x-ray examination is done to detect
abnormalities
in the colon.
● Ultrasonography shows the size and configuration of solid organs.
● Virtual colonoscopy combines computed tomography (CT) scanning or magnetic
resonance imaging (MRI) to produce images of the colon and rectum.
● GI structures that can be examined by endoscopy include the esophagus, stomach,
duodenum, and colon. Retrograde cholangiopancreatography (ERCP) is an endoscopic
procedure that visualizes the pancreatic, hepatic, and common bile ducts.
● Capsule endoscopy is a noninvasive approach to visualize the GI tract.
● Liver biopsy is done to obtain tissue for diagnosing cancer and staging of fibrosis.
● Liver function tests reflect hepatic disease and function.
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Test
Reference Interval
Description and Purpose
Blood Studies
Amylase
60–120 U/L (30–220 U/L)
Enzyme secreted by pancreas. Important in diagnosing
acute pancreatitis. Level peaks in 24 hr and then
returns to normal in 48–72 hr
Gastrin
25–100 pg/mL when fasting
Hormone secreted by cells of the antrum of the stomach,
the duodenum, and the pancreatic islets of
Langerhans
Lipase
0–160 U/L
Enzyme secreted by pancreas. Important in diagnosing
pancreatitis. Level stays higher longer than serum
amylase in acute pancreatitis
Fecal analysis
Note form, consistency, and color.
Specimen examined for mucus, blood,
pus, parasites, and fat content
Teach patient to keep diet free of red meat for 24–48 hr
before occult blood test
Fecal DNA testing
Negative
Detects shredded cell debris from polyps, adenomas, and
cancers
Fecal occult blood
Negative
Detects blood in stool related to the presence of
inflammatory bowel disease, diverticulosis, ulcers,
cancer, and other GI problems
Stool culture
Normal intestinal flora
Tests for the presence of bacteria, including Clostridium
difficile
Fecal Tests
For liver function tests look at chart 43.13
A Lot of people with gastric problems complain of left arm pain
Avoid using straws because of extra air
LOOK AT QUESTION AT END OF CHAPTER