Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Chapter 29

Disorders of Hepatobiliary and Exocrine Pancreas Function

Liver Structure• Blood from

hepatic portal vein and hepatic artery mix in sinusoids

• The sinusoids empty into central veins, which send the blood to the hepatic vein and inferior vena cava

Liver Structure(cont.)

• Hepatic cells lie along the sinusoids and pick up chemicals from the blood

• They modify the blood’s composition

Liver Structure(cont.)

• At the back end of each hepatic cell, bile is released into a canaliculus

• The bile is carried to the bile duct and then to the gallbladder

Liver Structure(cont.)

• Many sinusoids come together to empty into one vein

• The section of the liver emptying into one vein is a lobule

Question

Tell whether the following statement is true or false.

The gallbladder stores bile that has been produced by the liver.

Answer TrueRationale: The liver makes bile and secretes it

into the small intestine via the common bile duct. Excess bile is stored in the gallbladder, where it also enters the small intestine through the common bile duct when it is needed.

Metabolic Functions of the Liver • Carbohydrate, protein, and lipid metabolism

– Sugars stored as glycogen, converted to glucose, used to make fats

– Proteins synthesized from amino acids; ammonia made into urea

– Fats oxidized for energy, synthesized, packaged into lipoproteins

Metabolic Functions of the Liver (cont.)• Drug and hormone metabolism

– Biotransformation into water-soluble forms– Detoxification or inactivation

• Bile production

Question Which of the following substances makes bile

more susceptible to digestive enzymes?a. Carbohydrateb. Proteinc. Fatd. All of the above

Answer c. FatRationale: Bile (produced in the liver) emulsifies

fat molecules so that they are easier to digest. An emulsion is a mixture of two immiscible (unblendable) substances, in this case bile and fat.

ScenarioMr. M had a donut for breakfast. Question:• Explain how the sugar in the donut left his small

intestine and ended up as fat in his carotid artery, giving the:– Anatomical structures– Chemical processes– Hormones that controlled them

ScenarioMs. B was prescribed an oral medication for her skin problem.

She took it twice a day.• The day after she started the medication, Ms. B drank wine

with a friend right after taking the prescribed dosage Question:• Ms. B got terribly ill. Why? She said, “I drink that kind of

wine all the time.”

Liver Failure• Hematologic disorders

– Anemia, thrombocytopenia, coagulation defects, leukopenia

• Endocrine disorders– Fluid retention, hypokalemia, disordered sexual

functions– Which hormones would cause these endocrine

disorders?

Liver Failure (cont.)• Skin disorders

– Jaundice, red palms, spider nevi• Hepatorenal syndrome

– Azotemia, increased plasma creatinine, oliguria• Hepatic encephalopathy

– Asterixis, confusion, coma, convulsions

Question What causes jaundice?a. Increased bilirubin levelsb. Anemiac. Thrombocytopeniad. Leukopenia

Answer a. Increased bilirubin levelsRationale: Erythrocytes are normally broken down

in the spleen at the end of their life span. The end product of RBC metabolism is bilirubin. Bilirubin is sent to the liver to be metabolized; if the liver is not functioning properly, the bilirubin accumulates and causes jaundice (an abnormal yellowing of the skin and mucous membranes).

Hepatitis • Viral hepatitis• Hepatitis A virus (HAV)• Hepatitis B virus (HBV)• Hepatitis B–associated delta virus (HDV)• Hepatitis C virus (HCV)• Hepatitis E virus (HEV)

DiscussionWhich hepatitis viruses are most likely to be

the problem in:

• An asymptomatic drug abuser?

• A nursing student who has spent the last two months volunteering in an orphanage in Mali?

• An infant whose mother has hepatitis?

Chronic Viral Hepatitis• Caused by HBV, HCV, and HDV• Principal worldwide cause of chronic liver disease, cirrhosis,

and hepatocellular cancer• Chief reason for liver transplantation in adults

Alcoholic Liver Disease • Fatty liver (steatosis)

– Liver cells contain fat deposits; liver is enlarged• Alcoholic hepatitis

– Liver inflammation and liver cell failure• Cirrhosis

– Scar tissue partially blocks sinusoids and bile canaliculi

Question Which of the following is the least virulent strain

of hepatitis?a. HAVb. HBVc. HCVd. HDV

Answer a. HAVRationale: HBV, HCV, and HDV are all virulent

strains that may lead to chronic viral hepatitis. HAV is most commonly transmitted by the fecal-oral route (e.g., contaminated food or poor hygiene) and does not typically have a chronic stage (it does not cause permanent liver damage).

Veins Draining into the Hepatic Portal System

• Portal hypertension causes pressure in these veins to increase

• Varicosities and shunts develop

• Organs engorge with blood

Portal Hypertension

Cholestasis and Intrahepatic Biliary Disorders

• Bile flow in the liver slows down• Bile accumulates and forms plugs in the ducts

– Ducts rupture and damage liver cells• Alkaline phosphatase released into blood

• Liver is unable to continue processing bilirubin– Increased bile acids in blood and skin

• Pruritus (itching)

The Fate of Bilirubin• Hemoglobin from old red

blood cells becomes bilirubin

• The liver converts bilirubin into bile

• Why would a man with liver failure develop jaundice?

unconjugated bilirubin in

blood

bilirubinemia

jaundice

liver links it to

gluconuride

conjugated bilirubin

bile

Biliary Tract

Hepatic duct

Pancreatic duct

Gallbladder

Cystic duct

Common bile duct

Ampulla of Vater

Sphincter of Oddi

Disorders of the Gallbladder • Cholelithiasis (gallstones)

– Cholesterol, calcium salts, or mixed• Acute and chronic cholecystitis

– Inflammation caused by irritation due to concentrated bile

• Choledocholithiasis– Stones in the common bile duct

• Cholangitis – Inflammation of the common bile duct

Bile in the Intestines• Emulsifies fats so they can be digested• Passes on to the large intestine

– Bacteria convert it to urobilinogenº Some is lost in fecesº Most is reabsorbed into the blood

Returned to the liver to be reused Filtered out by the kidneys urine

The Pancreas Pancreas

Exocrine pancreas

releases digestive juices through a

duct

to the duodenum

Endocrine pancreas

releases hormones into the blood

Exocrine Pancreas • Acini produce:

– Inactive digestive enzymes

– Trypsin inactivator– Bicarbonate (antacid)

• These are sent to the duodenum when it releases secretin and cholecystokinin

• In the duodenum, the digestive enzymes are activated

Question Tell whether the following statement is true or

false.The exocrine pancreas produces insulin.

Answer FalseRationale: Beta cells of the endocrine pancreas

produce insulin; the exocrine pancreas produces digestive enzymes that are secreted into the small intestine through the common bile duct.

Biliary Reflux5. Bile in pancreas disrupts tissues; digestive enzymes activated

4. Bile goes up pancreatic duct

1. Gallbladder contracts

2. Bile is sent down common bile duct

3. Blockage forms in ampulla of Vater: bile cannot enter duodenum

Autodigestion of the Pancreas• Activated enzymes begin to digest the pancreas cells

– Severe pain results– Inflammation produces large volumes of serous exudate

hypovolemia• Enzymes (amylase, lipase) appear in the blood• Areas of dead cells undergo fat necrosis

– Calcium from the blood deposits in themº Hypocalcemia

Chronic Pancreatitis and Pancreatic Cancer

• Have signs and symptoms similar to acute pancreatitis• Often have:

– Digestive problems because of inability to deliver enzymes to the duodenum

– Glucose control problems because of damage to islets of Langerhans

– Signs of biliary obstruction because of underlying bile tract disorders or duct compression by tumors