The Digestive System Part 2. Bowel Infections 2 Clostridium difficile: An opportunistic infection...
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The Digestive System Part 2. Bowel Infections 2 Clostridium difficile: An opportunistic infection associated with broad-spectrum antibiotic use (a suprainfection)
Clostridium difficile: An opportunistic infection associated
with broad-spectrum antibiotic use (a suprainfection). E. coli
O157:H7: A strain of E. coli that produces a toxin that can make
some humans very sick. This strain of E. coli is carried by cattle
and is transmitted to humans through fecal contamination. 3
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E. coli O157:H7 4
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Not everyone infected with E. coli O157:H7 gets diarrhea or any
other symptoms. Ex. people who work around cattle their entire
lives may be immune to the strain Some people get very sick or even
die. Some may develop hemolytic-uremic syndrome. Some may develop
thrombotic thrombocytopenic purpura (TTP). 5
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Bowel Infections Appendicitis 6
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Appendicitis is a localized infection of the appendix, which is
a blind outpouching from the cecum. 7
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Appendicitis Signs and Symptoms 8
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Manifests as ill-defined pain starting in the area of the
umbilicus and later progressing to the lower right quadrant. Fever
is an undependable sign. A feeling of abdominal fullness and
wanting to defecate is common. The bowel is shut down because of
inflammation. Bowel sounds will be absent and the patient may think
he/she is constipated. Vomiting or loss of appetite is common. If
the appendix ruptures, pain may abate to return later with signs of
an acute abdomen. 9
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Diverticulitis 10
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Diverticulitis Diverticuli are outpouchings that have developed
throughout the intestine, although they are most common in the
large bowel. Most adults have them to some degree, some more than
others They can get infected and rupture, similar to the appendix.
Signs and symptoms are similar to appendicitis except they may not
necessarily be on the right lower quadrant 11
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Duodenal Diverticuli 12
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Duodenal Diverticuli 13
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Irritable Bowel Syndrome Diagram 14
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An 80-year-old man with a history of irritable bowel syndrome
presented with a 5-day history of abdominal pain in the left lower
quadrant, without aggravating or relieving factors Fisher R and
Doma S. N Engl J Med 2009;361:286 15
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Stages of Diverticulitis 16
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Jacobs D. N Engl J Med 2007;357:2057-2066 Stages of
Diverticulitis Antibiotics are prescribed to treat the infection.
Abscesses may be drained percutaneously. In about 10% of cases,
surgery is necessary to remove a section of the colon or even to
remove the entire colon (total colectomy) 17
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Colorectal Cancer Polyps 18
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Colorectal Cancer Polyps Third cause of death from cancer for
both men and women Most colorectal cancer starts out as a benign
polyp which progresses to carcinoma in situ and finally to invasive
cancer. Not all polyps progress to cancer. Most polyps bleed
sporadically. Bleeding can be detected by the fecal occult blood
test (FOBT). 19
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Colorectal Cancer Treatment 20
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Colorectal Cancer Treatment We can prevent the development of
most colorectal cancer by removing all polyps. Do not know which,
if any, will become cancer but just to be safe all of them should
be removed Polyps, and therefore colorectal cancer, develop in the
lumen of the colon. In order to become metastatic, the cancer has
to invade the smooth muscle of the intestine and gain access to
blood vessels and/or the peritoneal cavity. If the cancer has not
invaded very far, the prognosis is very good. If it has
metastasized, colorectal cancer always metastasizes to the liver
and sometimes elsewhere. 21
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Colonoscopy Diagram 22
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23 Fu K and Sano Y. N Engl J Med 2006;355:1912 A 56-year-old
man underwent a colonoscopy after a positive fecal occult-blood
test 23
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The Gallbladder Diagram 24
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The Gallbladder Diagram Porth, 2007, Essential of
Pathophysiology, 2 nd ed., Lippincott, p. 632 25
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Components of Bile 26
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Components of Bile 1.Bile salts are detergents which emulsify
fat for digestion. 2.Bile pigments are mainly conjugated bilirubin.
3.Cholesterol. 27
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Function of the Gallbladder 28
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Function of the Gallbladder The gallbladder also concentrates
the bile by removing water If it removes too much water, it can
precipitate the bile (which is usually made of cholesterol) Many
people have gallstones and do not even know it The problems come
when the gallstones leave the gallbladder and get stuck somewhere
29
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Causes of Gallstones 30
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Guyton & Hall, Textbook of Medical Physiology, 9 th ed.,
Saunders, 1996, p.830. Causes of Gallstones 31
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Gallstones Diagram 32
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Yekeler & Akyol, NEJM 351:2318, 2004 33
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34 Porth, 2007, Essential of Pathophysiology, 2 nd ed.,
Lippincott, p. 653 34
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Treatment of Gallstones 35
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Treatment of Gallstones Since it is felt that new stones will
probably re-form if we just remove the stones, the gall bladder is
usually removed. When the gall bladder is no longer present, the
bile will not be as concentrated and precipitation of the
components probably will not occur. Gall bladder surgery is
typically done endoscopically through the abdominal wall. In
patients who are not candidates for surgery, stones can be
fragmented with lithotripsy. If they are in the duct, they can be
crushed endoscopically from the stomach. There are drugs that
dissolve gallstones, but they are not used very much. 36
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The Liver Diagram 37
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Porth, 2007, Essential of Pathophysiology, 2 nd ed.,
Lippincott, p. 633 The Liver Diagram 38
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Functions of the Liver 39
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Functions of the Liver A. Carbohydrate metabolism B. Lipid
metabolism. C. Protein and energy metabolism. 1.Enzymes important
in energy metabolism: ALT, AST, GGT - Used as tests for liver
necrosis 2. Synthesis of plasma proteins: albumin, coagulation
factors, etc. 40
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Blood Flow of the Liver 41
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Blood Flow of the Liver 1.Hepatic artery: 350 ml/min 2.Portal
vein: 1100 ml/min 3.Total blood flow: 1450 ml/min, 29% of resting
cardiac output. 4.The liver is drained by the hepatic vein, which
enters the inferior vena cava. 42
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Detoxification 43
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Detoxification The liver binds polar molecules to drugs and
other molecules. This is called conjugation. Conjugating drugs and
other molecules makes them easier to excrete, either by the kidney
or in the bile. Bilirubin is detoxified by conjugation (addition)
of a glucuronic acid molecule. 44
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Bilirubin Formation, Circulation, and Elimination Diagram
45
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Porth, 2007, Essential of Pathophysiology, 2 nd ed.,
Lippincott, p. 636 The process of bilirubin formation, circulation
and elimination Urobilinogen is responsible for the brown color of
the stool 46
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Excretion by the Liver 47
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Excretion by the Liver Bile is the vehicle for excretion What
is excreted? 1. Some drugsmost are conjugated before excretion 2.
Bilirubin 3. Cholesterol 48
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Hepatitis 49
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Hepatitis Means inflammation of the liver. Stating hepatitis
does not indicate what the cause is, just that there is
inflammation. There are several different etiologies: 1.Toxic
Hepatitis is caused by drugs/chemicals like halothane or isoniazid.
2.Bacterial hepatitis is caused by such organisms as TB, Staph, or
Pseudomonas 3.Parasitic hepatitis is caused by a variety of
parasites 4.Viral hepatitis is caused by such viruses as Epstein
Barr, and Hepatitis A, B, or C - This is usually what the person
means 50
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Hepatitis A: Viral 51
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Hepatitis A: Viral Sort of a mild disease May feel sick, but
most people do not die from hepatitis A Vaccine available No
carrier state You have it and then you get over it and do not have
it anymore Caused by oral ingestion of contaminated water or food
(fecal- oral route). Lifetime protection against re-infection if
you get either the vaccine or the infection 52
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Hepatitis B: Viral 53
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Hepatitis B: Viral Vaccine available Carrier (chronic active)
state Spread by parenteral routes and exchange of body fluids For
the majority of hepatitis B patients, it is unknown how they got it
because there is a long incubation period and the person does not
remember Long incubation period Acute disease can last weeks or
months Afterward may get rid of the disease or may go into an
active chronic hepatitis and have it forever 54
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Hepatitis B: Viral Diagram 55
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Hepatitis B: Viral Diagram Porth, 2007, Essential of
Pathophysiology, 2 nd ed., Lippincott, p. 640 56
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Progression/Outcomes of Hepatitis B Infection 57
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Kumar et al, 2010, Robbins & Cotran, Pathologic Basis of
Disease, 8 th ed. Elsevier, Progression/Outcomes of Hepatitis B
Infection 58
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Blood Markers of Acute Hepatitis B Infection and Recovery
59
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Blood Markers of Acute Hepatitis B Infection and Recovery Kumar
et al, 2010, Robbins & Cotran, Pathologic Basis of Disease, 8
th ed. Elsevier, 60
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Blood Markers of Chronic Active Hepatitis B Infection 61
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Blood Markers of Chronic Active Hepatitis B Infection Kumar et
al, 2010, Robbins & Cotran, Pathologic Basis of Disease, 8 th
ed. Elsevier, 62
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Hepatitis C 63
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Hepatitis C Parenteral routes of transmission. Carrier (chronic
active) state is more frequent with hepatitis C than with hepatitis
B. Blood tests are available for the virus itself or for
antibodies. 64
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Progression/Outcomes for Hepatitis C 65
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Kumar et al, 2005, Robbins & Cotran, Pathologic Basis of
Disease, Elsevier, p.894 Progression/Outcomes for Hepatitis C
66
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A patient has the following lab tests: Hepatitis B viral DNA is
negative; IgG- anti-HBc is positive. IgM-anti-HBc is negative. What
can we say about this patient? 67
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A patient has the following lab tests: Hepatitis B viral DNA is
negative; IgG-anti-HBc is positive. IgM-anti-HBc is negative. What
can we say about this patient? 1.He has active hepatitis B 2.He is
contagious with hepatitis B 3.He was exposed to hepatitis B in the
past but has recovered 4.We can't tell whether he has active
hepatitis B from these tests 68
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Characteristics of Hepatitis A, Hepatitis B, and Hepatitis C
69
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Characteristics of Hepatitis A, Hepatitis B, and Hepatitis C
Point of comparisonHepatitis AHepatitis BHepatitis C Causative
agentHepatitis A virusHepatitis B virusHepatitis C virus Infections
that become chronicNone3%-5%>70% Acute infections each year in
the US 179,000185,00038,000 US residents with chronic infection
None1.25 million2.7 million Annual deaths in the US from chronic
infection None60008000-10,000 People worldwide with chronic
infection None350 million170 million Method of preventionHepatitis
A vaccine Hepatitis B vaccineHepatitis C vaccine (not yet
available) Preferred treatmentNoneInterferon alfa or lamivudine
Interferon alfa plus ribavirin Adapted from Lehne, 2009,
Pharmacology for Nursing Care, 7 th ed., Elsevier, p. 1076 70
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Complications of Chronic Active Hepatitis B or C 71
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Complications of Chronic Active Hepatitis B or C Cirrhosis with
portal hypertension may manifest as: 1. Varices in the GI tract 2.
Ascites 3. Congestive splenomegaly Hepatocellular carcinoma Liver
failure may manifest as: 1. Low coagulation factors/bleeding 2. Low
serum albumin lowers the serum osmolic pressure/edema 3. Hepatic
encephalopathy 72
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Features of Cirrhosis 73
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Features of Cirrhosis 1.Fatty liver: reversible, caused by
alcohol consumption and many other things. 2.Fibrosis: not
reversible; hepatic vasculature is rearranged, causing portal
hypertension and varices. 74
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The Liver and its Venous Vasculature 75
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Porth, 2007, Essential of Pathophysiology, 2 nd ed.,
Lippincott, p. 633 The Liver and its Venous Vasculature 76
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Consequences of Cirrhosis/Liver Failure 77
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Consequences of Cirrhosis/Liver Failure 1.Portal hypertension
with varices 2.Ascites - The pressure in the liver vasculature is
so great that fluid is squeezed out of the vasculature and into the
portal cavity 3.Portosystemic venous shunts 4.Congestive
splenomegaly - Blood backs up out of the liver 5.Hepatic
encephalopathy - Brain problems and confusion due to buildup of
ammonia because it cannot be converted into urea and excreted from
the body 78
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Consequences of Liver Failure 79
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Porth, 2007, Essential of Pathophysiology, 2 nd ed.,
Lippincott, p. 649 Consequences of Liver Failure 80
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Consequences of Portal Hypertension 81
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Porth, 2007, Essential of Pathophysiology, 2 nd ed.,
Lippincott, p. 646 Consequences of Portal Hypertension 82
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Portal Hypertension and the Diversion of Blood Flow Diagram
83
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Porth, 2007, Essential of Pathophysiology, 2 nd ed.,
Lippincott, p. 648 Portal Hypertension and the Diversion of Blood
Flow Diagram 84
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Portal Hypertension and the Diversion of Blood Flow 85
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Portal Hypertension and the Diversion of Blood Flow The portal
veins drain the lower part of the esophagus and the stomach
Normally, blood is going through the blood vessels, down the veins,
into the liver and the portal vein Other blood goes through the
vessel into the vena cava If there is a backup, the blood cannot
get through the liver and it results in portal hypertension The
veins enlarge and you get varicosities in the lower esophagus and
throughout the gastrointestinal tract People can actually bleed to
death from lower esophageal varices 86
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Porto-systemic Venous Shunts 87
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Porto-systemic Venous Shunts 88 Caput medusa. Esophageal
varices. Yang P and Chen D. N Engl J Med 2005;353:e19 88
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Varices Caused by Portal Hypertension 89
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Varices Caused by Portal Hypertension The varices in the
esophagus are typically the most troublesome and bleed, sometimes
profusely. Bleeding varices can also develop in the stomach or
intestinal mesentery. Internal hemorrhoids are varices of veins
that drain the rectum and are frequently caused by liver disease.
(External hemorrhoids are not caused by liver disease and are
almost a universal finding in people over about age 30). 90
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Causes of Ascites Liver Disease 91
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Causes of Ascites Liver Disease Causes: 1. Increased lymph
formation by liver with transudation through hepatic capsule.
Transudation involves the slow escape of liquids from blood vessels
through pores or breaks in cell membranes. 2. Sodium and water
retention by kidney. 3. Hypoalbuminemia 92
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Ascites Diagram 93
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Ascites Diagram 94
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Cirrhosis Diagram 95
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A 52-year-old man with cirrhosis associated with alcohol abuse
presented to the emergency department with hematemesis and
lightheadedness, which had developed 3 hours earlier, after binge
drinking Torrazza-Perez E and Carreno N. N Engl J Med 2010;362:e13
Video: http://www.nej m.org/doi/full/1 0.1056/NEJMic m0807812
96
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Other Consequences of Liver Failure 97
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Other Consequences of Liver Failure Congestive splenomegaly
caused by portal hypertension. Hepatic encephalopathy: not sure of
cause, but probably ammonia is not the whole story. Difficulty in
metabolizing particular drugs (acetaminophen). 98
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Hepatocellular Carcinoma 99
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Hepatocellular Carcinoma Associated with cirrhosis, hepatitis
B, or hepatitis C Environmental toxins can cause it (aflatoxins).
The liver is a favorite site of metastasis for many different kinds
of cancer that arise elsewhere, such as colon, breast, and lung.
These cancers are not liver cancers. 100