Hepatic Secretions

Question 1

Hepatocyte border

Answer 1

sinusoids (blood), space of Disse (lymph), and bile cancliculi (bile)

Question 2

Discontinuous capillaries

Answer 2

allows passage of proteins into blood

Question 3

Tight junctions

Answer 3

prevent mixing of bile, blood, lymph

Question 4

Bile allows secretion of

Answer 4

organic, high MW, and hydrophobic molecules that annot be excreted in urine

Question 5

Bile is composed of

Answer 5

bile acids, phospholipids, cholesterol, HCO, bilirubin, water

Question 6

Bile acids function

Answer 6

ampipathic, formation of micelle for digestion of fat (phospholipids, choleterol, long chain FFA)

Question 7

Liver synthesizes primary bile acids

Answer 7

cholic acid and chenodeoxycholic acid from cholesterol

Question 8

cholesterol 7alpha-hydroxylase

Answer 8

synthesize cholic acid

Question 9

oxysterol 7alpha-hydroxylase

Answer 9

synthesizes chenodeoxycholic acid

Question 10

Enterohepatic circulation

Answer 10

circulation of bile acids from liver, gall bladder, duodenum, colon, to liver via portal vein

Question 11

During fasting, bile acids in portal venous blood is ______ so rate of syntehesis is

Answer 11

Low, synthesis high

Question 12

During a meal, bile acids in portal venous blood is ______ so rate of syntehesis is

Answer 12

High, synthesis low

Question 13

Passive absorption of bile acids occurs in

Answer 13

colon and proximal small intestine

Question 14

Carrier mediated absorption of bile acids occurs in

Answer 14

ileum and liver

Question 15

Sodium-dependent bile acid transporter (ASBT)

Answer 15

mediated uptake of bile acid in enterocytes of ileum (MAJOR MECHANISM)

Question 16

Sodium-dependent transport proteins (NTCP) and Sodium-independent organic anion transport

Answer 16

mediate uptake of bile acids in the liver

Question 17

ATP-dependent bile salt export (BSEP)

Answer 17

liver secretes bile acid into canaliculi

Question 18

Multi-drug resistant-associated protein 2 (MRP2)

Answer 18

secretion of sulfated or glucuronidated bile acids into canaliculi

Question 19

Secondary bile acids are formed by

Answer 19

bacteria in the colon

Question 20

defect in bile acid formation may be due to

Answer 20

increased bile acid excretion in feces, loss of bile acid flow, decreased cholesterol absorption,

Question 21

defects in membrane transport of bile acid

Answer 21

mutation in transporter protein

Question 22

Defects involving bacterial transformation

Answer 22

bacterial overgrowth depletes bile acids

Question 23

Defects in bile acid circulation

Answer 23

obstruction, crohn’s, celiac

Question 24

Bilirubin

Answer 24

RBC death and binding of unconjugated bilirubin to albumin

Question 25

UGT1A1

Answer 25

liver enzyme that conjugates bilirubin to two glucuronic acids

Question 26

Excretion of liver

Answer 26

conjugated bilirubin is excreted into the bile (RATE-limiting step)

Question 27

conjugated bilirubin in the colon is converted to

Answer 27

urobilinogen

Question 28

Urobilinogen can be excreted in urine as ______ or feces as _______

Answer 28

urobilin; stercobilin

Question 29

Jaundice

Answer 29

accumulation of bilirubin in the blood

Question 30

Indirect bilirubin >80-85% of total indicated

Answer 30

unconjugated hyperbilirunemia; hemolysis of RBC, impaired conjugation, impaired hepatic uptake of bilirubin

Question 31

Causes for indirect bilirubin

Answer 31

hemolysis, neonatal jaundice, Gilbert’s syndrome, prolonged fasting, sepsis

Question 32

Direct bilirubin >50% of total

Answer 32

conjugated hyperbilirubinemia; defect in transfer from liver to canaliculi or transfer through ducts

Question 33

Causes of direct bilirubin

Answer 33

hepatocellular disease, alcoholic liver, intra- or extraheptic obstruction

Question 34

If there is bilirubin in urine, which type of bilirubinemia is indicated?

Answer 34

conjugated, since unconjugated is bound to albumin and cannot be filtered

Question 35

Urobilinogen high in urine?

Answer 35

excessive hemolysis or hepatic uptake impaired

Question 36

Urobilinogen low in urine?

Answer 36

obstruction

Question 37

Bilirubin is a part of bile, but it is not

Answer 37

recirculated it is excreted

Question 38

Water secretion into bile canaliculi is due to

Answer 38

solvent drag as bile acids are secreted into cancaliculi

Question 39

Secretin causes

Answer 39

HCO3 secretion through bile duct epithelial cells

Question 40

When the bile in the canaliculi increases, presure causes bile to flow down duct to either

Answer 40

gallbladder (if resistance to filling is low) or to duodenum (if Sphincter of Oddi resistance is low)

Question 41

During fasting the bile flows to

Answer 41

gallbladder, (sphincter of oddi is resistant)

Question 42

Concentration of Bile in gall bladder is achieved by

Answer 42

Na absorption from lumen into gallbladder epithelium and formation of micelles, BOTH are required for H2O flux from gall bladder

Question 43

Factors that cause bile to flow from gall bladder to duodenum

Answer 43

vagal stimulation, food consumption, CCK release,

Question 44

Cholesterol Gall Stones

Answer 44

1. excessive bile cholesterol 2. Mucin: nucleation of cholesterol 3. abnormal gall bladder motor function