Liver

Q: What are geneal characteristics of the liver?

• largest & complex organ in body

• lies inferior to the diaphragm

• suspended from diaphragm & anterior abdominal wall by falciform ligament

Q: What is the bare area of the liver?

• large area that rest directly above the diaphragm

• Isn’t covered by peritoneum

Q: What is the approx. size of the liver

• Sag. = 13 - 17.5 cm

• Trans. = 21 - 22.5 cm

Typically 15 - 17 cm**

Q: What are characteristics of the right lobe?

• occupies right hypochondrium

• largest of 3 lobes

Q: What are the 3 fossae associated w/ the rt. lobe?

• porta hepatis fossa

• GB fossa

• IVC fossa

Q: What are characteristics of the left lobe?

• lies in epigastic & left hypochondriac

• always smaller than right lobe

Q: What are characteristics of the caudate lobe?

• smallest lobe

• lies on posterosuperior surface of the left lobe

• separated by ligamentum venosum

Couinaud’s Segments

1. Caudate Lobe

2. Superior lateral segment left lobe

3. inferior lateral segment left lobe

4a & 4b Medial segment left lobe

5. Inferior anterior segment right lobe

6. inferior posterior segment right lobe

7. superior posterior segment right lobe

8. superor anterior segment right lobe

Q: What is the main lobar fissure?

• boundary between the right & left lobe

• seen on longitudinal scan

• hyperechoic line

  • from portal vein → neck of GB

Q: What are characteristics of the falciform ligament?

• extends from umbilicus to diaphragm

• contains ligamentum teres

Q: What are characteristics of the ligamentum Teres?

• divides the medial & lateral segments of the left lobe

• bright echogenic focus

• rounded terminations of falciform ligament

• circle or triangular w/ posterior shadowing

Q: What are characteristics of the lgamentum venosum?

• separates left lobe from caudate lobe

• linear horizontal line

  • inferior to dome of liver

  • anterior to caudate lobe

Q: What is the porta hepatis?

• central area of liver where these enter/exit:

  • portal vein

  • common duct

  • hepatic artery

• location

  • anterior to caudate lobe

  • posterior to medial segment of left lobe

Q: How is the main portal vein formed?

• formed by union of:

  • splenic vein (SV)

  • superior mesenteric vein (SMV)

• anterior to IVC

• serves to located the liver hilum

Q: What does the main portal vein divide into?

• Rt. portal vein (RPV)

• Lt. portal vein (LPV)

Q: What are characteristics of the right portal vein?

• larger

• supplies the right lobe

• posterior & caudal approach

• branches into:

  • anterior

  • posterior

Q: What are characteristics of the left portal vein?

• smaller

• supplies the left lobe

• anterior & cranial approach

• branches into:

  • medial

  • lateral

Q: how many hepatic veins are there?

• right

• middle

• left

Q: what are the characteristics of the right hepatic vein?

• largest

• enters on right lateral aspect of IVC

Q: what are the characteristics of the middle and left hepatic veins?

• both enter on anterior surface of IVC

• tend to share a trunk

• left is the smallest

Q: How do hepatic veins and portal veins differ in their course and appearance?

• Hepatic veins: course between hepatic lobes/segments & become larger as they drain into the IVC

• Portal veins: larger at their origins & have more echogenic borders/walls

Q: what are the characteristics of the hepatic artery?

• arises from celiac trunk to supply liver

  • common hepatic artery

• becomes proper hepatic artery before entering the porta hepatis

• right & left branch of hepatic artery accompany portal veins

Q: What do the intrahepatic vessles/ducts carry or drain?

• Portal veins: carry blood from the bowel to the liver

• Hepatic veins: drain blood from the liver

• Hepatic artery: carries oxygenated blood to the liver

Q: what are the functions of the liver?

• metabolism

• Digestion

• Storage

• Detoxification

Q: What are enzymes & why are they elevated w/ liver disease?

Enzymes = protein catalysts for metabolic processes

• present in hepatocytes

  • leak into bloodstream when liver cells are damaged or destroyed by disease

Q: What hepatic enzymes are there?

• Aspartase aminotransferase (AST)

• Alanine aminotransferase (ALT)

• Alkaline phosphatase

Q: What is hepatocellular liver disease?

• liver cells hepatocytes are involved

  • treated medically w/ supportive measures & drugs

Q: What is obstructive liver disease?

• bile excretion is blocked

  • treated surgically

Q: What is the liver’s role in detoxification?

• major site for detox of waste products

  • energy production

  • breakdown of foreign chemicals (drugs)

Q: What happens to ammonium (NH4) in the liver?

• toxic product of nitrogen metabolism

  • converted to nontoxic urea

Q: What happens to urea after it’s produced?

• eliminated by the kidneys

• level of urea = blood urea nitrogen (BUN)

Q: What happens to BUN in severe acute or chronic liver disease?

• BUN may be abnormally low

  • due to falloff of urea production

Q: What is bilirubin & what does the liver do with it?

• breakdown product of hemoglobin

• liver converts byproducts into bile pigments

  • excretes into bile ducts

Q: What is indirect bilirubin and when is it elevated?

AKA. unconjugated bilirubin

• Elevated w/ increased red blood cell destruction

• Examples:

  • Anemias

  • Trauma from a hematoma

  • Hemorrhagic pulmonary infarct

Q: What is direct bilirubin and what is it associated with?

AKA. conjugated bilirubin

• Circulates in the blood

• Excreted into bile after reaching the liver & being conjugated with glucuronide

• Elevation is usually related to obstructive jaundice

  • caused by gallstones or neoplasm

Q: What does an elevation of bilirubin result in?

Jaundice → is a nonspecific finding

• Yellowish tint to:

  • Skin

  • Sclerae

  • Body secretions

Q: What conditions can cause jaundice?

• Massive blood breakdown (indirect)

• Hepatocellular disease (direct)

• Biliary obstruction (direct)

Q: How can bilirubin levels help distinguish hepatocellular disease from obstruction?

uncommon for total bilirubin to rise above 35 mg/100 mL of serum

• above this is typically hepatocellular

Q: What is the liver's role in hormone detoxification?

• Breaks down several hormones

• Prevents hormones from building up in the body

Q: What is the liver's role in drug detoxification?

• Primary location for breakdown of medications

• Also breaks down other foreign chemicals

Q: Why may medication doses need to be reduced in people with severe liver disease?

• Loss of detoxification function

• Drugs may accumulate

• Accumulation may lead to overdose

Q: What are the characteristics of bile formation?

• Formation of bile is an exocrine function

• Hepatocytes form bile

• Bile is secreted into tiny ducts

Q: How does bile flow in the tiny ducts?

• Bile flows in the opposite direction of blood

• This prevents mixing

Q: What is bile composed of?

• 97% water

• Bile salts and pigments

• Inorganic salts:

  • Sodium chloride

  • Sodium bicarbonate

Q: What is the important function of bile salts?

• Bile salts are fat-solubilizing agents

• Can mix with fat and water

• Increase fat solubility

Q: How do bile salts help with fat digestion?

• Increase fat solubility

• Allows fats to be digested by the water-soluble enzyme lipase

• Lipase comes from the pancreas

Q: What are liver function tests?

• Group of various laboratory tests

• Analyze how the liver is performing under normal and diseased conditions

Q: What information do serum liver tests provide?

• Indirect information about hepatic pathophysiology

• Best method for evaluating liver disease

  • liver biopsy examination

Q: When is aspartate aminotransferase (AST) elevated?

• Hepatitis

• Cirrhosis

• Hepatic necrosis

• Acute hepatitis

• Infectious mononucleosis

NOT liver specific (found in other muscles or organ tissues)**

Q: When can AST become elevated in relation to jaundice?

before the patient experiences jaundice

Q: How does alanine aminotransferase (ALT) compare with AST?

• More specific than AST for evaluating liver function

• Specific indicator of hepatocellular damage

• Used in conjunction with AST

Q: What can high AST with mildly elevated ALT indicate?

Cardiac damage

Q: What causes lactic acid dehydrogenase (LDH)to increase?

• Cellular injury

• Cellular death

Q: In what conditions can LDH be elevated?

• Moderate increase: infectious mononucleosis

• Mild elevation:

  • Hepatitis

  • Cirrhosis

  • Obstructive jaundice

Q: What can alkaline phosphatase be an indicator of?

• Intrahepatic obstruction (small ducts)

• Extrahepatic obstruction (biliary tree)

• Hepatic carcinoma (other cancers typically cause this)

• Abscess (bacterial infection)

• Cirrhosis (scarred liver/can’t regenerate)

Q: What diseases can cause elevated total bilirubin levels?

• Hepatic metastasis

• Hepatitis

• Lymphoma

• Cholestasis secondary to drugs

• Cirrhosis

Q: What is prothrombin and what does its production depend on?

• Liver enzyme involved in the blood-clotting mechanism

• Production depends on adequate intake and use of vitamin K

Q: When is prothrombin time increased?

• Liver disease with cellular damage

• Examples:

  • Cirrhosis

  • Metastatic disease

Q: What does depressed synthesis of serum proteins indicate?

• Sensitive test for metabolic derangement of the liver

• Especially involves:

  • Serum albumin

  • Plasma coagulation factors

Q: What do prolonged prothrombin time and elevated gamma globulins indicate?

• Prolonged prothrombin time: poor prognosis

• Chronic liver disease: commonly shows elevated gamma globulins

Q: What are the characteristics of portal flow?

• Hepatopetal

  • Mild pulsatility

Q: What are the characteristics of hepatic flow?

• Hepatofugal

  • Pulsatile

Q: What are the characteristics of hepatic artery flow?

• Hepatopetal

• Low-resistance forward flow