Hepatobiliary Function

Question 1

Dual blood supply to liver:

Answer 1

• Hepatic Artery (20-30%)
• Portal Vein (70-80%)

Question 2

Main Functions of Liver:

Answer 2

• Bile production and secretion
• Metabolism of carbs, proteins and lipids
• Bilirubin production and excretion
• Detoxification of substances

Question 3

Metabolic Functions of Liver: Protein Synthesis

Answer 3

• Synthesis of non-essential AAs
• Modification of AA for use in biosynthetic pathways for carbs
• Synthesis of almost all plasma proteins (ex. albumin, clotting factors)
• Conversion of ammonia (byproduct of protein catabolism) to urea

Question 4

Liver failure can result in ______ which may lead to edema

Answer 4

Hypoalbuminemia

Question 5

Bile Composition:

Answer 5

• Bile Salts (50%)
• Bile Pigments (2%) – ex. Bilirubin
• Cholesterol (4%)
• Phospholipids (40%) – ex. lecithin
• Ions
• Water

Question 6

Bile Function:

Answer 6

• Vehicle for the elimination of substances from the body
• Solves the insolubility problem of lipids

Question 7

Location of Bile Synthesis:

Answer 7

Hepatocytes (Liver)

Question 8

Location of Dehyroxylation of Primary Bile Acids to Secondary Bile Acids:

Answer 8

Lumen of Intestines

Question 9

Location of Conjugation of Secodary Bile Acids:

Answer 9

Liver

Question 10

Newly synthesized bile acids and returning bile acids (recycled from enterohepatic circulation) are secreted into the ___ ___

Answer 10

Bile Canaliculi

Question 11

Bile Canaliculi

Answer 11

• Located between Hepatocytes
• Move bile away from the center of the lobule and out to the bile duct

Question 12

What occurs in the Duodenum?

Answer 12

Emulsification and digestion of fats

Question 13

What occurs in the Jejunum?

Answer 13

Micelle formation and fat absorption

Question 14

What occurs in the Ileum?

Answer 14

• Active absorption of conjugated form of bile acid (>90% of bile acids is absorbed into Portal blood here)
• Involved in recycling conjugated bile acids back to liver

Question 15

Recycled bile acids return to liver in ___ circulation

Answer 15

Portal

Question 16

What occurs in the Gallbladder?

Answer 16

Storage and concentration of bile between meals

Question 17

Almost all bile formation is driven by:

Answer 17

Bile Acids (bile acid-dependent)

Question 18

A small portion of bile is stimulated by ___ and is secreted from the ducts – known as ____ ___-___ or ___ ___

Answer 18

• Secretin
• Bile Acid-Independent
• Ductular Secretion

Question 19

During the Interdigestive period, Gallbladder fills with bile:

Answer 19

• Gallbladder is relaxed
• Sphincter of Oddi is closed

Question 20

On Eating, CCK-mediated:

Answer 20

• Contraction of the Gallbladder
• Relaxation of the Sphincter of Oddi

Question 21

Uptake of Bile Salts across the Basolateral membrane of the hepatocytes is mediated by two types of systems:

Answer 21

(1) Na+-dependent transport protein, Sodium Taurocholate Co-Transporting Polypeptide (NTCP)
(2) Na+-independent transport protein, Organic Anion Transport Proteins

Question 22

Rate of Bile Acid Synthesis & Secretion: Ileal Resection

Answer 22

• Do not have enough Bile Acid because it is not being reabsorbed in the Ileum
• Increased rate of bile acid synthesis
• Decreased rate of bile acid secretion

Question 23

Rate of Bile Acid Synthesis & Secretion: Bile Acid Feeding/Excess

Answer 23

• Decreased rate of bile acid synthesis
• Increased rate of bile acid secretion

Question 24

Cholesterol 7alpha Hydroxylase is inhibited by:

Answer 24

Bile Acids/Salts

Question 25

Unconjugated bilirubin toxicity in the CNS damages:

Answer 25

- Neurons - Astrocytes (increased release of inflammatory factors) - Microglia (increased release of inflammatory factors) - Oligodendrocytes (decreased myelin synthesis)

Question 26

Biochemical Liver Function Tests: ALT

Answer 26

- Type of serum aminotransferase - Very specific to the liver

Question 27

Biochemical Liver Function Tests: AST

Answer 27

- Type of serum aminotransferase - Nonspecific -- found in other tissue besides the liver

Question 28

What 3 Liver enzymes are commonly measured in the serum?

Answer 28

(1) ALT (2) AST (3) Alkaline Phosphatase

Question 29

Elevated aminotransferases (ALT and AST) are primarily the result of:

Answer 29

Hepatocyte injury

Question 30

Elevated Alkaline Phosphatase are primarily the result of:

Answer 30

Bile Duct injury (ex. Cholestasis)

Question 31

Liver Function Tests: Albumin

Answer 31

- Synthesized exclusively in the liver - Levels of this protein fall as the synthetic function of the liver declines with worsening cirrhosis - Severe impairment of hepatocyte function is likely to reduce the level of this protein in the plasma

Question 32

_____ is not specific to liver disease; it may also be seen in Kidney Glomerular Disease

Answer 32

Hypoalbuminemia

Question 33

Liver Function Tests: Prothrombin Time (PT)

Answer 33

- Reflects the degree of hepatic synthetic dysfunction - PT increases when hepatic synthesis of clotting factors is impaired - PT increases as the ability of a cirrhotic liver to synthesize clotting factors diminishes

Question 34

Saliva Secretion: Characteristics

Answer 34

- High [HCO3-] - High [K+] - Hypotonic - Alpha amylase and lingual lipase

Question 35

Saliva Secretion: Factors that Increase Secretion

Answer 35

PNS

Question 36

Saliva Secretion: Factors that Decrease Secretion

Answer 36

- Sleep - Dehydration - Atropine

Question 37

Gastric Secretion: Characteristics

Answer 37

- HCl - Pepsinogen - Intrinsic Factor (IF)

Question 38

Gastrin Secretion: Factors that Increase Secretion

Answer 38

- HCl is increased by Gastrin, ACh and Histamine - Pepsinogen is increased by PNS

Question 39

Gastric Secretion: Factors that Decrease Secretion

Answer 39

- H+ in the stomach - Chyme in the duodenum - Somatostatin - Atropine - Cimetidine - Omeprazole

Question 40

Pancreatic Secretion: Characteristics of Aqueous Secretion

Answer 40

- High [HCO3-] - Isotonic

Question 41

Pancreatic Secretion: Characteristics of Enzyme Secretion

Answer 41

Pancreatic Lipase, Amylase and Proteases

Question 42

Pancreatic Secretion: Factors that Increase Aqueous Secretion

Answer 42

- Secretin - PNS

Question 43

Pancreatic Secretion: Factors that Increase Enzyme Secretion

Answer 43

- CCK - PNS

Question 44

Bile Secretion: Characteristics

Answer 44

- Bile salts - Bilirubin - Phospholipids - Cholesterol

Question 45

Bile Secretion: Factors that Increase Secretion

Answer 45

- CCK -- causes contraction of gallbladder and relaxation of sphincter of Oddi - PNS

Question 46

Bile Secretion: Factors that Decrease Secretion

Answer 46

Ileal Resection