Liver Physiology (Lecture 1)

What are hepatocytes?

Functional liver cells that synthesize, metabolize, and excrete products

What are Kupffer cells?

fixed reticuloendothelial liver cells that remove and phagocytize old and defective blood cells, bacteria, and other foreign materials

What are endothelial cells in the liver?

Cells forming bile canaliculi and ductules.

What is a hepatic lobule?

Cylindrical functional unit of the liver that is made up of hepatocyte plates radiating from the central vein, emptying into the HVs and IVC

What are sinusoids? What vessels are they supplied by? (HINT: 2)

- Thin-walled veins separating hepatic plates

- Supplied by PVs and HVs

What are bile canaliculi?

Channels lygin b/w hepatocytes that carry bile from hepatocytes to bile ducts (centre --> periphery)

What is gluconeogenesis?

Glucose production from non-carbohydrate sources

(function of liver)

Name 3 functions of the liver

- Metabolizes hormones and drugs

- Synthesizes proteins, glucose, clotting factors (RBCs in fetal liver)

- Convert ammonia to urea, fatty acids to ketones, and sugar to fat

- Stores vitamins, minerals, and glucose as glycogen

- Secretes bile and secretory proteins (albumin)

- Immunity: filters blood, removes bacteria and particles, and phagocytize of old WBCs & RBCs

- Vascular reservoir

- Detoxification

What is bile?

- End products of substances metabolized by liver (ex. H2O, bile salts, bilirubin, cholesterol, etc.)

- Involved in fat digestion, fat and fat-soluble vitamin absorption

What is albumin?

Protein maintaining plasma osmotic pressure (fluid electrolyte balance)

What are LFTs?

Tests assessing liver function and injury.

What is prothrombin time?

Measures time for fibrin clot formation

TRUE or FALSE: If prothrombin time is elevated, clotting factors are not being produced.

TRUE: If prothrombin time is increased, it is taking more time for clotting factors to be produced.

What is serum alkaline phosphatase (SAP)? What do increased levels indicate?

- Indicator of bile duct disorders

- Increased = bile duct disorder

What does increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) indicate? (HINT: 4)

hepatitis, necrosis, myocardial infarction, cirrhosis

What is fibrinogen?

plasma protein involved in clotting process

What does increased and decreased albumin indicate?

- Increased = multiple myeloma (bone marrow cancer)

- Decreased = hepatic disease

What does increased unconjugated bilirubin indicate?

Hepatic damage

What does increased conjugated bilirubin indicate?

Biliary obstruction

What is AFP? When does it indicate when it's elevated?

- Glycoprotein produced in fetal tissue

- Elevated in non-pregnant person = hepatocellular carcinoma (HCC)

What is another name for jaundice?

icterus

What is the cause of prehepatic jaundice? Is unconjugated or conjugated bilirubin elevated?

- Caused by excessive RBC destruction

- Increased unconjugated bilirubin

What is Intrahepatic jaundice? Is unconjugated or conjugated bilirubin elevated?

- Due to impaired uptake, conjugation, and excretion of bilirubin

- Impaired uptake = inc unconjugated bilirubin

- Impaired excretion (but conjugated) = inc conjugated bilirubin

What is posthepatic jaundice? Is unconjugated or conjugated bilirubin elevated?

- Resulting from bile duct obstruction

- Increased conjugated bilirubin

Describe gallium studies (cells of uptake, positive exam feature, and 3 possible diagnoses)

- Uptake by wandering RBCs

- When positive, aggregate (clump together) to create hot spots

- Correlates to inflammation, infection, or malignancy

Describe Tc-Sulfur Colloid studies (cells of uptake, positive exam feature, and 3 possible diagnoses)

- Uptake by Kupffer cells

- Positive = cold spots

- Correlates to abscess, cyst, or hematoma

Name 3 clinical presentations of liver dysfunction.

- Jaundice

- Hemorrhage

- Ascites

- Hypoglycemia

- Encephalopathy

- Infection

What are the steps for bilirubin production?

1. Old RBCs breakdown, making hemoglobin → heme + globin

2. Heme → biliverdin → unconjugated bilirubin (fat soluble)

3. Unconjugated bilirubin is conjugated by hepatocytes when entering the liver

4. Conjugated bilirubin (water soluble) goes thru bile ducts → CBD → intestines

5. Bacteria in large intestine converts bilirubin → urobilinogen

6. Urobilinogen excreted in urine, some bilirubin excreted in feces, and some circulates back to liver