GI Physiology 5

Question 1

Some key functions of the liver include

Answer 1

Nutrient metabolism
Synthesis of serum proteins
Storage of nutrients 
Immune function 
Detoxification/Biotransformation

Question 2

Biliary system consists of

Answer 2

Network of ducts that carry the hepatic secretory product (bile) to the intestine; and a bile storage site (the gallbladder)

Question 3

Biliary system is critical for

Answer 3

Assimilation of dietary lipids
Excretion of hydrophobic compounds
Neutralization of gastric acid

Question 4

Blood flow in the liver - The GI organs drain into the

Answer 4

portal vein

Question 5

Blood flow in the liver - what percentage of blood that flows to the liver comes from the portal vein?

Answer 5

75%

The remaining 25% is delivered by the hepatic artery

Question 6

Blood flow in the liver - from the liver, the blood drains from the ____ into ___

Answer 6

From the hepatic veins into the IVC

Question 7

Blood flow in the liver - the portal venous system delivers blood to the liver - thus….

Answer 7

Contents absorbed via the GI tract have to “pass through” the liver

Question 8

Portal hypertension

Answer 8

Inc in pressure in the portal venous system that occurs when there is dysfunction within the portal system
You will end up with pooling of blood in the GI organs

Thus - looking at GI organs can be indicator for liver dysfunction

Question 9

Lobules of the liver - Blood and bile flow in same/opp directions in the liver lobules

Answer 9

OPPOSITE

Question 10

Lobules of the liver - blood from the portal vein and hepatic artery empty into

Answer 10

Sinusoids - It flows toward the central vein

Question 11

Lobules of the liver - Bile will flow

Answer 11

Away from the central vein and towards the bile duct

Question 12

Describe the structure of the biliary system

Answer 12

Tree like

Question 13

Biliary tree - a small ductal system referred to as ____ empty into the ___ ____

Answer 13

Canaliculi empty into the bile ductule

The canaliculi interface directly with the hepatocyte

Question 14

Biliary tree The bile ductile then empties into

Answer 14

The bile or hepatic ducts that then drain into the common bile duct

Question 15

Cells of the liver

Answer 15

Hepatocytes
Kupffer
Endothelial
Stellate cells

Question 16

Cells of the liver - Hepatocytes

Answer 16

Functional cells of the liver
Polarized epithelial cells
Interface blood and bile

Question 17

Cells of the liver - Kupffer

Answer 17

Phagocytic macrophades
Exposed to portal blood
Host defense mechanism

Question 18

Cells of the liver - endothelial

Answer 18

Large pores between cells

Minimal basement membrane - they are not packed together tightly and have pores btw them

Question 19

Cells of the liver - Stellate

Answer 19

In the pores of the endothelial cells

The regulate the flow of blood (or bile) to the hepatocytes

Question 20

Key steps in hepatocyte biotransformation

Answer 20

Uptake
Transport
Biotransformation
Secretion

Question 21

Key steps in hepatocyte biotransformation - Uptake

Answer 21

Import of compound across the basolateral membrane

Question 22

Key steps in hepatocyte biotransformation - Transport

Answer 22

Intracellular transport (they will bind to other transports and will be carried within the cell)

Question 23

Key steps in hepatocyte biotransformation - Biotransformation

Answer 23

Chemical modification of degredation

Question 24

Key steps in hepatocyte biotransformation - Secretion

Answer 24

Secrete products across apical or basolateral membrane
Put it back into the blood or put it into the bile

Water soluble - into blood
Less water soluble - into bile

Question 25

Key steps in hepatocyte biotransformation - Biotransformation - phase 1

Answer 25

Chemical rxns like oxidation, reduction, hydrolysis – You are taking the compound and adding a functional group to make them more water soluble/more polar

Question 26

Key steps in hepatocyte biotransformation - Biotransformation - phase 2

Answer 26

Conjugation rxn
We add a large/bulky group to the molecule to make it more water soluble

Add things like Glucoronidation, Sulfation, Acetylation, Glycine Conjugation, Glutathione conjugatin

Question 27

Key steps in hepatocyte biotransformation - goal of biotransformation

Answer 27

Take compounds and make them more water soluble

Question 28

Bile acid synthesis - Bile acids and bile salts use what for synthesis

Answer 28

Biotransformation

Question 29

Bile acid synthesis - One way is that primary bile acid (cholic acid) is first

Answer 29

Secreted into the bile
Goes through to bile duct and then duodenum
Primary is then converted to secondary and we inc diversity of our bile salts

Question 30

Bile acid synthesis - Another way is that primary bile acid (cholic acid) can undergo

Answer 30

Biotransformation process (phase 1 and 2) and then we convert it to bile salt (which is more water soluble)

Question 31

Bile acid synthesis - summary

Answer 31

From the liver, we get a mixture of bile acids and bile salts to be secreted into the duodenum

Cholesterol is used to synthesize the bile acids and bile salts along with the biotransformation process

Question 32

Enterohepatic circulation of bile acids and salts - liver will secrete bile - how many grams of bile acids and salts are in the bile that is secreted compared to how many bile acids/salts we make in a day

Answer 32

4-6 grams

So liver makes 0.5 g of bile acid/salt a day - but 4-6 g is secreted in bile

Question 33

Enterohepatic circulation allows for

Answer 33

Recycling of approx 90-95% of the bile acid/salt

Question 34

Enterohepatic circulation - Ileum

Answer 34

Plays important role

Ileum expresses a Na bile salt co transporter and is the primary site for update of bile acid/salt

Question 35

Enterohepatic circulation - Two important things taken up by the small intestine

Answer 35

Bile acids/salts and Vit B12

Question 36

Regulation of bile secretion

Answer 36

CCK stimulates gallbladder to contract and release bile

CCK also causes relaxation of sphincter of oddi which allows passage opening of bile into intestine

Question 37

Regulation of bile secreteion - key players

Answer 37

CCK and Ach

Somatostatin will counteract both Ach and CCK

Question 38

Liver function evaluation - Hepatocyte damage

Answer 38

Elevation of enzymes like alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the systemic circulation

Elevated ALT and AST indicates hepatocyte damage (markers of cell death)

Question 39

Liver function evaluation - Impaired protein synthesis

Answer 39

Dec in serum proteins in systemic circulation (albumin, clotting factors)
Indirectly can measure clotting time

Question 40

Liver function evaluation - Impaired biotransformation

Answer 40

You will get an increase in concentration of compounds that require conjugation for elimination - like estrogen, or bilirubin

Can also get accumulations of toxins line ammonia

Question 41

Liver function evaluation - Impaired bile flow (so blockage, liver is not damaged)

Answer 41

Inc concentration of conjugated bilirubin in the systemic circulation (leads to jaundice)

Dec bile pigments in stool (leading to gray color of it)

Dec bile secreted into the intestine (leading to fatty stool)

Question 42

Hepatocytes and conjugation

Answer 42

We need hepatocytes to conjugate molecules

Question 43

Liver function evaluation - do we have hepatocyte toxicity or do we have impaired bile flow

Answer 43

If there is conjugated bilirubin for example, that suggests that the liver function is good, but flow has decreased (so there is a blockage)

If it were unconjugated - then we would think liver damage

Question 44

Portal hypertension is a sign of what

Answer 44

Liver dysfunction

High blood pressure in the portal venous system

Question 45

Consequences of portal hypoertension

Answer 45

Varices
Splenomegaly
Ascites
Hepatic encephalopathy