Chapter 29 Disorders of Hepatobiliary and Exocrine Pancreas Function

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Chapter 29

Disorders of Hepatobiliary and Exocrine Pancreas Function


Liver StructureLiver 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.)Liver Structure(cont.)

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

• They modify the blood’s composition



• 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



• Many sinusoids come together to empty into one vein

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


Question Question

Tell whether the following statement is true or false.

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


Answer Answer

True

Rationale: 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 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.)Metabolic Functions of the Liver (cont.)

• Drug and hormone metabolism

– Biotransformation into water-soluble forms

– Detoxification or inactivation

• Bile production


Question Question

Which of the following substances makes bile more susceptible to digestive enzymes?

a. Carbohydrate

b. Protein

c. Fat

d. All of the above


Answer Answer

c. Fat

Rationale: 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.


ScenarioScenario

Mr. 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


ScenarioScenario

Ms. 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 FailureLiver 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.)Liver Failure (cont.)

• Skin disorders

– Jaundice, red palms, spider nevi

• Hepatorenal syndrome

– Azotemia, increased plasma creatinine, oliguria

• Hepatic encephalopathy

– Asterixis, confusion, coma, convulsions


Question Question

What causes jaundice?

a. Increased bilirubin levels

b. Anemia

c. Thrombocytopenia

d. Leukopenia


Answer Answer

a. Increased bilirubin levels

Rationale: 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 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)


DiscussionDiscussion

Which 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 HepatitisChronic 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 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 Question

Which of the following is the least virulent strain of hepatitis?

a. HAV

b. HBV

c. HCV

d. HDV


Answer Answer

a. HAV

Rationale: 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 SystemVeins Draining into the Hepatic Portal System

• Portal hypertension causes pressure in these veins to increase

• Varicosities and shunts develop

• Organs engorge with blood


Portal HypertensionPortal Hypertension


Cholestasis and Intrahepatic Biliary DisordersCholestasis 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 BilirubinThe 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 TractBiliary Tract

Hepatic duct

Pancreatic duct

Gallbladder

Cystic duct

Common bile duct

Ampulla of Vater

Sphincter of Oddi


Disorders of the Gallbladder 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 IntestinesBile in the Intestines

• Emulsifies fats so they can be digested

• Passes on to the large intestine

– Bacteria convert it to urobilinogen

º Some is lost in feces

º Most is reabsorbed into the blood

Returned to the liver to be reused

Filtered out by the kidneys urine


The PancreasThe PancreasPancreas

Exocrine pancreas

releases digestive juices through a

duct

to the duodenum

Endocrine pancreas

releases hormones into the blood


Exocrine Pancreas 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 Question

Tell whether the following statement is true or false.

The exocrine pancreas produces insulin.


Answer Answer

False

Rationale: 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 RefluxBiliary 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 PancreasAutodigestion 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 them

º Hypocalcemia


Chronic Pancreatitis and Pancreatic CancerChronic 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

Chapter 29 Disorders of Hepatobiliary and Exocrine Pancreas Function

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