Anatomy and Physiology of the GI System, Hormonal Control, Upper GI Tract Disorders, Gallbladder Disorders, Liver Disorders, Pancreatic Disorders, Lower GI Tract Disorders

1. Gastrointestinal
Pathophysiology

3. The Stomach
• 4 layers
 Mucosa
 Submucosa
 Circular muscular layer
 Longitudinal muscle layer
 Serosa
• Peristalsis
 Key physiologic process
 Involuntary contractions of the
stomach
 Occur in circular and longitudinal
smooth muscle layers

4. Cells of the Stomach
• Gastrin Cells, G Cells
 Initiated by food entering the stomach
 Stimulate parietal cells and chief cells
• Intrinsic Factor, Parietal Cells
 Needed for the absorption of vitamin B12
• HCl Cells, Parietal Cells
 Activate pepsinogen to create an optimal pH of 2
 Denature proteins
• Pepsinogen, Chief Cells
 Not activated until stomach acid has a pH of 6

5. The Liver: Functions
• Storage of nutrients
• Maintains blood glucose
• Blood reservoir
• Produces bile, plasma proteins, blood clotting
factors, cholesterol, and lipoproteins
• Takes part in metabolic processes

7. The Liver: Storage Processes
• Glycogenesis
 Glucose is converted to glycogen
 When glycogen supply is low
• Glyconeogenesis
 Proteins and fats are converted to glycogen
• Glycogenolysis
 Glycogen is converted to glucose
 Maintain blood glucose levels

8. Pancreas
• Exocrine Organ because it secretes digestive enzymes and
electrolytes
• Endocrine Organ because it secretes insulin and glucagon
• Important Molecules –
 Trypsin, chymotrypsin, carboxypeptidase
 Break proteins
 Ribonuclease
 Break nucleic acids
 Pancreatic Amylase
 Break starch
 Lipase
 Break lipids

9. Gallbladder
• Stores bile, fluids, fat,
and cholesterol
• Bile breaks down fat from
food in your intestine
• Delivers bile into the
small intestine

10. GI Tract
• Ileum
 Major site of nutrient absorption
 Occurs in the folds of mucosal linings (villi)
• Large Intestine
 Fluid and electrolyte reabsorption
 Movement is slow to allow for absorption of water
 Vitamin K synthesis is essential for blood clotting

11. Small Intestine Large Intestine

12. Neural Control of the GI Tract
• Parasympathetic Nervous System
Vagus Nerve
Increased gastric motility
Increased gastric acid secretions
• Sympathetic Nervous System
Inhibits gastrointestinal activity

13. Hormonal Control of the GI Tract
• Gastrin
Increases gastric motility
Promotes stomach emptying
• Secretin
Decreases gastric acid secretions
• Cholecystokinin
Inhibits gastric emptying

14. Upper GI Tract Disorders
• Dysphagia
 Difficulty swallowing
 Causes: neurological deficit, muscular disorder, or mechanical
obstruction
• Esophageal Cancer
 Squamous cells in the distal esophagus. Poor prognosis.
 Causes: chronic irritation, chronic esophagitis, hiatal hernia
• Hiatal Hernia
 Part of the stomach protrudes into the thoracic cavity

15. Upper GI Tract Disorders
• GERD
 Gastric substances reflux into the distal esophagus, often
seen with hiatal hernia
 Cause: decrease competence of the lower esophageal
sphincter
• Gastritis
 Stomach mucosa is inflamed, can be acute or chronic
 Causes of acute gastritis: food allergies, spicy food, excessive
alcohol, or ulcerogenic drugs
 Causes of chronic: idiopathic or helicobacter pylori infection
• Gastroenteritis
 Inflammation of the stomach and intestine

18. Upper GI Tract Disorders
• Peptic Ulcers
 Erosion in the mucosa is common
in the proximal duodenum and
the antrum of the stomach
 Rarely found in the large
intestine
 Causes: H. pylori infection,
increased acid-pepsin secretions,
inadequate blood supply,
excessive glucocorticoid secretion,
and ulcerogenic substances

19. Upper GI Tract Disorders
• Stress Ulcers
Rapid onset, may form within hours of
the precipitating event
Causes
 Severe Trauma
 Curling’s Ulcers – Burns
 Cushing’s Ulcers – Head Injury
 Systemic Causes
 Ischemic Ulcers – Hemorrhage, Sepsis

20. Upper GI Tract Disorders
• Gastric Cancer
 Primarily in the mucous glands and in the
antrum or pyloric area of the stomach
 Poor prognosis
• Pyloric Stenosis
 Narrowing and obstruction of pyloric sphincter
 May be a developmental anomaly or acquired
later in life

22. Gallbladder Disorders
• Cholelithiasis
 Formation of gallstones
• Cholecystitis
 Inflammation of gallbladder and cystic duct
• Cholangitis
 Inflammation related to bile duct infection
• Choledocholithiasis
 Obstruction of biliary tract by gallstones, due to the
presence of larger stones

23. Liver Disease
• Jaundice – yellowish color of skin, sign of disease
 Prehepatic
 Unconjugated bilirubin is elevated
 Cause: excessive destruction of red blood cells
 Intrahepatic
 Unconjugated and conjugated bilirubin are elevated
 Cause: disease or damage to hepatocytes
 Posthepatic
 Conjugated bilirubin is elevated
 Cause: obstruction of bile flow into the gallbladder or duodenum

24. Liver Disease
• Hepatitis – inflammation of the liver
 Mild
 Impaired hepatocyte function
 Severe
 Impaired hepatocyte function
 Necrosis and obstruction of blood and bile flow
 Cause
 Idiopathic – fatty liver
 Infection – viral or non-viral

25. Liver Disease: Viral Hepatitis
• Hepatitis A
 Infectious hepatitis. RNA virus.
 Transmitted by fecal-oral route in areas of inadequate sanitation.
 No carrier or chronic stage. Vaccine available.
• Hepatitis B
 Serum hepatitis. DNA virus.
 Incubation period of 2 months.
 Primarily transmitted through infectious blood but can also be
transmitted through sexual contact or from mother to fetus.
 Carriers are asymptomatic but contagious. Vaccine is available.
 Ascites in Chronic Hepatitis B
 Engorgement of blood vessels so that toxins can no longer be filtered

26. Liver Disease: Viral Hepatitis
• Hepatitis C
 RNA virus. Most common type.
Transmitted via blood transfusion. Has carrier state.
 Increases risk of hepatocellular carcinoma.
• Hepatitis D
 Delta virus.
 Incomplete RNA virus – needs hepatitis B to produce an
active infection.
 Transmitted through blood.
• Hepatitis E
 RNA virus. No carrier or chronic stage.
 Transmitted by fecal-oral route.

27. Liver Disease
• Cirrhosis – progressive destruction of the liver
Stage 1
 Fatty liver. Asymptomatic and reversible.
Stage 2
 Alcoholic hepatitis. Irreversible.
Stage 3
 End stage cirrhosis.
 Liver failure occurs when 80-90% of the liver is
destroyed.

29. Liver Disease
• Liver Cancer – initial signs are mild; diagnosis
occurs with advanced stages
 Hepatocellular Carcinoma
 Most common primary tumor of the liver
 Metastatic Liver Cancer
 Arises from areas served by the hepatic vein

31. Pancreatic Disease
• Acute Pancreatitis
 Can be chronic or acute; chronic in 15% of cases
 Spreads to tissue surrounding the pancreas
 Very painful; different from pancreatic cancer
 Results from auto-digestion of tissues around the
pancreas due to the premature activation of
pancreatic pro-enzymes
 Precipitating Factors: most common is alcohol;
others are biliary tract obstruction, gallstone, or the
mumps.

33. Pancreatic Disease
• Pancreatic Cancer
Adenocarcinoma is the most
common form
Asymptomatic until advanced
Metastasizes quickly
Mortality rate of 95%
Risk factors: smoking,
pancreatitis, and dietary factors

34. Lower GI Tract Disorders
• Celiac Disease
 Malabsorption syndrome prevents the digestion of gliadin,
or the breakdown of gluten. Villi atrophy.
 Causes: autoimmune disease, defect in intestinal enzyme
• Appendicitis
 Obstruction of the appendiceal lumen
 Wall becomes inflamed as fluid builds in the appendix
 Symptoms: lower right quadrant rebound tenderness,
periumbilical pain
 Causes: fecalith, gallstones, or foreign object cause
obstruction

36. Lower GI Tract Disorders
• Crohn’s Disease
 Progressive inflammation
and fibrosis cause obstructed
areas in the intestine
 Normally affects the small
intestines but may affect any
part of the GI tract
 Inflammation occurs in skip
lesions
 Cause: genetic factor, often
occurring during adolescence

37. Lower GI Tract Disorders
• Ulcerative Colitis
 Blood and mucous present in
the stool
 Inflammation starts in the
rectum and progresses to the
colon
 Cause: genetic factor, often
occurring during the 2nd or 3rd
decade

38. Lower GI Tract Disorders
• Diverticular Disease
 Diverticulum
 An abnormal sac or pouch formed at a weak point in the wall
of the alimentary tract
 Diverticulosis
 Asymptomatic; outpouching of the mucosa through the
muscular layer of the colon
 Diverticulitis
 Inflammation of the diverticula; very painful
• Cause – can be genetic
• Symptoms – cramping, tenderness, nausea, fever, elevated
WBC, and no blood in stool

40. Lower GI Tract Disorders
• Colorectal Cancer
 Early diagnosis is essential for good prognosis
 Second most diagnosed cancer
 Symptoms: alternating diarrhea/constipation,
bleeding, weight loss, anemia, red blood in stool,
pain is not typical.
 Cause: adenomatous polyps are the most
common
 Risk Factors: familial multiple polyps, long-
term ulcerative colitis, and increased
susceptibility due to low fiber diets

42. Lower GI Tract Disorders
• Intestinal Obstruction – lack of movement of
intestinal contents; most common in the small
intestine
 Mechanical Obstruction
 Tumors, adhesions
 Functional Obstruction
 Impairment of peristalsis
 Ex. spinal cord injury

43. Lower GI Tract Disorders
• Peritonitis
 Inflammation of peritoneal membranes
 Symptoms: sudden and severe generalized
abdominal pain, abdominal distension,
dehydration, low blood pressure, tachycardia, and
vomiting
Chemical Peritonitis
 Caused by foreign chemical in peritoneal cavity,
such as bile or chyme
Bacterial Peritonitis
 Direct trauma affecting the intestines, such as a
ruptured appendix or pelvic inflammatory disease

45. Lower GI Tract Disorders
• Irritable Bowel Syndrome
 Change in bowel motility associated with
affecting the large intestine
 Causes abdominal cramping and bloating
 Symptoms must be there 12 weeks out of the
year
 NO BLOOD in stool