Gastrointestinal
Module 9
GI System Anatomy and Physiology
Examine the anatomy and physiology of the GI system:
1. Differentiate between the organs which make up the upper gastrointestinal
track and the lower gastrointestinal track.
-The GI tract consists of the mouth, esophagus, stomach, small intestine, large
intestine, rectum, and anus.
-Upper GI tract - esophagus, stomach and duodenum (upper GI bleeds)
-Lower GI tract - jejunum, ileum, colon and rectum (lower GI bleeds)
2. Explain the hepatoportal circulation anatomy and physiology.
The hepatic portal vein collects blood from capillaries in visceral structures located in
the abdomen and empties into the liver for distribution to the hepatic capillaries.
Hepatic veins return blood to the inferior vena cava.
3. Discuss the effects of aging on the gastrointestinal tract.
Age related changes in the GI tract begins at age 50
Tooth enamel and dentin wear down→ more vulnerable to cavities
Teeth are lost as a result of:
o Periodontal (gum) disease
o Recession of gums
o Osteoporotic bone changes
o Brittle roots that fracture easily
Taste buds decline in number
Sense of smell diminishes
Sense of taste decreases
Salivary secretion decreases
Very old adults→ oral and sensory changes make eating less pleasurable and reduce
appetite
Food not chewed or lubricated sufficiently→ difficulty swallowing
Esophagus develops decreased motility
Changes in upper esophageal sphincter (hx of stroke & dementia) affect swallowing and
contribute to GERD
Gastric motility and volume decreases (secretion of bicarbonate & gastric mucus)
Decreased production of intrinsic factor→ inadequate small intestine absorption of
vitamin B12 and pernicious anemia
Change in composition of the intestinal microflora→ increased susceptibility to disease
, Intestinal absorption, motility, and blood flow decrease → impaired nutrient absorption
Proteins, fats, minerals(including Ca+ and Iron), and vitamins are absorbed slowly and in
lesser amounts.
Absorption of carbohydrates is decreased
Intestinal transit time = delayed
Constipation (probably caused by lifestyle factors)
Rate of liver regeneration decreases
Liver function altered (usually a pathologic condition)
Liver blood flow and enzyme activity decreased (influence the efficiency of drug and
alcohol metabolism)
Pancreas undergoes structural changes such as fibrosis, fatty acid deposits, atrophy
Pancreatic secretion decreases
Gallstone incidence increases
Examine the pathologic basis of adult and pediatric disorders which
affect the GI system:
Gastrointestinal Bleeds
4. Analyze the etiologies and pathophysiology of osmotic, secretory, and motility
related diarrhea.
Osmotic
Etiology:
-Large oral doses of poorly absorbed ions (magnesium, sulfate, phosphate) can
increase intraluminal osmotic pressure.
- Excessive ingestion of synthetic, nonabsorbable sugars (sorbitol), introduction of full
strength tube feeding formulas, dumping syndrome associated with gastric resection
draw water into the intestinal lumen.
-Malabsorption related to lactase deficiency, pancreatic enzyme or bile salt deficiency,
small intestine bacterial overgrowth, and celiac disease can also cause diarrhea
Patho:
A nonabsorbable substance in the intestine draws water into the lumen by osmosis.
The excess water and the nonabsorbable substance cause large- volume diarrhea
Osmotic diarrhea disappears when ingestion of the osmotic substance stops
Secretory
Etiology:
, Infectious causes include viruses (rotavirus), bacterial exotoxins ( Escherichia Coli,
Vibrio cholerae) or exotoxins from overgrowth of Clostridium difficile following abx
therapy
Neoplasms (gastrinoma or thyroid carcinoma)
Small volume diarrhea: -Inflammatory disorder of the intestine (Ulcerative colitis, Crohn
disease, or microscopic colitis)
-Fecal impaction
Patho:
The infections cause secretion of transmitters from enteroendocrine cells (5-HT) and
activation of afferent neurons that stimulate submucosal secretomotor neurons and
altered sodium and chloride transport resulting in decreased water absorption.
Produce hormones that stimulate intestinal secretion causes diarrhea
Inflammation of the colon causes smooth muscle contraction, cramping pain, urgency,
and frequency.
This diarrhea consists of secretions (mucus and fluid) produced by the colon to lubricate
the impacted feces and move it toward the anal canal. The secretions flow around the
impaction and cause low volume, secretory diarrhea
Motility
Etiology:
Is caused by resection of the small intestine (short bowel syndrome), surgical bypass of
an area of the intestine, fistula formation between loops of intestine, irritable bowel
syndrome-diarrhea predominant, diabetic neuropathy, hyperthyroidism, and laxative
abuse
Patho:
Excessive motility decreases transit time, mucosal surface contact, and opportunities for
fluid absorption, resulting in diarrhea
5. Analyze the etiology, clinical manifestations, and pathophysiology of the upper
and lower GI bleed and describe the implications this has for your clinical
practice as a nurse practitioner.
Upper GI bleed
Etiology:
-Bleeding varices in the esophagus or stomach
- Peptic Ulcers
-Gastritis
Module 9
GI System Anatomy and Physiology
Examine the anatomy and physiology of the GI system:
1. Differentiate between the organs which make up the upper gastrointestinal
track and the lower gastrointestinal track.
-The GI tract consists of the mouth, esophagus, stomach, small intestine, large
intestine, rectum, and anus.
-Upper GI tract - esophagus, stomach and duodenum (upper GI bleeds)
-Lower GI tract - jejunum, ileum, colon and rectum (lower GI bleeds)
2. Explain the hepatoportal circulation anatomy and physiology.
The hepatic portal vein collects blood from capillaries in visceral structures located in
the abdomen and empties into the liver for distribution to the hepatic capillaries.
Hepatic veins return blood to the inferior vena cava.
3. Discuss the effects of aging on the gastrointestinal tract.
Age related changes in the GI tract begins at age 50
Tooth enamel and dentin wear down→ more vulnerable to cavities
Teeth are lost as a result of:
o Periodontal (gum) disease
o Recession of gums
o Osteoporotic bone changes
o Brittle roots that fracture easily
Taste buds decline in number
Sense of smell diminishes
Sense of taste decreases
Salivary secretion decreases
Very old adults→ oral and sensory changes make eating less pleasurable and reduce
appetite
Food not chewed or lubricated sufficiently→ difficulty swallowing
Esophagus develops decreased motility
Changes in upper esophageal sphincter (hx of stroke & dementia) affect swallowing and
contribute to GERD
Gastric motility and volume decreases (secretion of bicarbonate & gastric mucus)
Decreased production of intrinsic factor→ inadequate small intestine absorption of
vitamin B12 and pernicious anemia
Change in composition of the intestinal microflora→ increased susceptibility to disease
, Intestinal absorption, motility, and blood flow decrease → impaired nutrient absorption
Proteins, fats, minerals(including Ca+ and Iron), and vitamins are absorbed slowly and in
lesser amounts.
Absorption of carbohydrates is decreased
Intestinal transit time = delayed
Constipation (probably caused by lifestyle factors)
Rate of liver regeneration decreases
Liver function altered (usually a pathologic condition)
Liver blood flow and enzyme activity decreased (influence the efficiency of drug and
alcohol metabolism)
Pancreas undergoes structural changes such as fibrosis, fatty acid deposits, atrophy
Pancreatic secretion decreases
Gallstone incidence increases
Examine the pathologic basis of adult and pediatric disorders which
affect the GI system:
Gastrointestinal Bleeds
4. Analyze the etiologies and pathophysiology of osmotic, secretory, and motility
related diarrhea.
Osmotic
Etiology:
-Large oral doses of poorly absorbed ions (magnesium, sulfate, phosphate) can
increase intraluminal osmotic pressure.
- Excessive ingestion of synthetic, nonabsorbable sugars (sorbitol), introduction of full
strength tube feeding formulas, dumping syndrome associated with gastric resection
draw water into the intestinal lumen.
-Malabsorption related to lactase deficiency, pancreatic enzyme or bile salt deficiency,
small intestine bacterial overgrowth, and celiac disease can also cause diarrhea
Patho:
A nonabsorbable substance in the intestine draws water into the lumen by osmosis.
The excess water and the nonabsorbable substance cause large- volume diarrhea
Osmotic diarrhea disappears when ingestion of the osmotic substance stops
Secretory
Etiology:
, Infectious causes include viruses (rotavirus), bacterial exotoxins ( Escherichia Coli,
Vibrio cholerae) or exotoxins from overgrowth of Clostridium difficile following abx
therapy
Neoplasms (gastrinoma or thyroid carcinoma)
Small volume diarrhea: -Inflammatory disorder of the intestine (Ulcerative colitis, Crohn
disease, or microscopic colitis)
-Fecal impaction
Patho:
The infections cause secretion of transmitters from enteroendocrine cells (5-HT) and
activation of afferent neurons that stimulate submucosal secretomotor neurons and
altered sodium and chloride transport resulting in decreased water absorption.
Produce hormones that stimulate intestinal secretion causes diarrhea
Inflammation of the colon causes smooth muscle contraction, cramping pain, urgency,
and frequency.
This diarrhea consists of secretions (mucus and fluid) produced by the colon to lubricate
the impacted feces and move it toward the anal canal. The secretions flow around the
impaction and cause low volume, secretory diarrhea
Motility
Etiology:
Is caused by resection of the small intestine (short bowel syndrome), surgical bypass of
an area of the intestine, fistula formation between loops of intestine, irritable bowel
syndrome-diarrhea predominant, diabetic neuropathy, hyperthyroidism, and laxative
abuse
Patho:
Excessive motility decreases transit time, mucosal surface contact, and opportunities for
fluid absorption, resulting in diarrhea
5. Analyze the etiology, clinical manifestations, and pathophysiology of the upper
and lower GI bleed and describe the implications this has for your clinical
practice as a nurse practitioner.
Upper GI bleed
Etiology:
-Bleeding varices in the esophagus or stomach
- Peptic Ulcers
-Gastritis
