3B Physiology of the Liver

Question 1

How much glycogen can liver cells store as a percentage of liver weight?

Answer 1

8% of liver cell weight 100-120g in adult

Question 2

Where does aa degradation occur almost entirely?

Answer 2

Liver

Question 3

What two enzymes are required for deamination in the liver?

Answer 3

AST and ALT, which are measure in blood to assess liver function

Question 4

Where is essentially all urea synthesized in the blood?

Answer 4

Liver

Question 5

What is a hepatic come or hepatic encephalopathy?

Answer 5

In serious liver disease, ammonia often accumulate in the blood

Question 6

Where is urea excreted?

Answer 6

Kidneys

Question 7

What is azotemia or uremia?

Answer 7

Toxic build up of urea in blood

Question 8

What can cause an elevated BUN?

Answer 8

Impaired renal function, increased protein intake or catabolism, GI bleeding, dehydration

Question 9

What is HMG-CoA-reductase?

Answer 9

important enzyme in liver hepatocytes required for endogenous cholesterol synthesis

Question 10

What is the only way for the body to eliminate excess cholesterol?

Answer 10

Via bile

Question 11

When does ketogenesis occur primarily?

Answer 11

Fasting states or poorly controlled type 1 diabetes

Question 12

How does ketogenesis affect the pH of blood?

Answer 12

Lower pH (more acidic)

Question 13

Does the liver degrade steroid hormones and T3 and T4?

Answer 13

Yes, sir!

Question 14

What is hemachromatosis?

Answer 14

To much Fe+2 that begins to deposit in tissues

Question 15

What does gastroferrin do?

Answer 15

Makes Fe+2 more soluble and transports it to the small intestine where it is released for absorption

Question 16

What is transferrrin? Apoferritin? Ferritin?

Answer 16

Transferrin carries Fe+2 to liver. In liver apoferretin takes Fe+2 to make soluble and the Fe+2 and apoferretin complex is now called Ferritin. Ferritin is the stored form of Fe+2 in the liver

Question 17

The liver stores large quantities of what vitamins?

Answer 17

A, B12, and D

Question 18

What is the purpose of metabolizing drugs?

Answer 18

Make less active and more water soluble and thus readily excreted in urine and bile

Question 19

Where are Cytochrome P450 enzymes most predominant?

Answer 19

Liver, intestines, lungs and other organs

Question 20

What are conjugation reactions designed to do?

Answer 20

Make metabolites more polar or hydrophilic, sometimes after they have been created by P450 enzymes

Question 21

What is the most common and most important conjugation reaction?

Answer 21

Glucuronidation

Question 22

What is CP450 inhibition?

Answer 22

Decreased metabolic activity of CP450 enzymes leading to decreased metabolism of drugs

Question 23

What is CP450 induction?

Answer 23

Increased metabolic activity of CP450 enzymes leading to increased metabolism of drugs

Question 24

What stimulates Vitamin D activation in the liver?

Answer 24

PTH

Question 25

What are the major types of plasma proteins?

Answer 25

Albumin, globulin, fibrinogen

Question 26

Which plasma proteins are completely formed in the liver? Which one is 50-80% formed in the liver?

Answer 26

Albumin and fibrinogen. Globulin is 50-80% formed in the liver

Question 27

Which blood clotting factors are synthesized in the liver?

Answer 27

All but III, IV and XIII

Question 28

What is the composition of bile?

Answer 28

50% bile salts 40% phospholipids 4% cholesterol 2% bile pigments such as bilirubin

Question 29

Does bile contain water?

Answer 29

Yes and electrolytes, these are secreted by cells lining the bile ducts

Question 30

What are the two primary bile acids? Where are they synthesized?

Answer 30

Cholic acid and chenodeocycholic acid. Synthesized in the hepocytes

Question 31

What converts a portion of the primary bile acids into secondary bile acids? What is the name of the secondary bile acids?

Answer 31

Intestinal bacteria does the conversion. Secondary bile acids are called deoxycholic acid and lithocholic acid

Question 32

The liver conjugates bile acids with what two possible amino acids to form bile salts?

Answer 32

Glycine or taurine

Question 33

What does the conjugation of bile acids w/ glycine or taurine do?

Answer 33

Makes the bile acids amphipathic at duodenal pH

Question 34

What is the most common phospholipid found in bile?

Answer 34

Lecithin

Question 35

Are phospholipids amphipathic?

Answer 35

Yes, sir!

Question 36

The majority of cholesterol breakdown in the body is turned into what in the liver?

Answer 36

Bile

Question 37

How much cholesterol is converted into bile acids and eliminated daily?

Answer 37

500 mg

Question 38

What is the waste product of Hb degradation?

Answer 38

Bilirubin

Question 39

What does conjugation of bilirubin involve? What enzyme is needed?

Answer 39

Attachmen of glucuronic acid to bilirubin. | Glucuronyl transferase

Question 40

Which type of bilirubin is more water soluble?

Answer 40

Conjugated bilirubin

Question 41

What cells secrete ions and water into the bile?

Answer 41

Ithelial cells lining the bile ducts

Question 42

What are other waste products that go into the bile?

Answer 42

Lipolithic drugs and metabolites, antigen-antibody complexes

Question 43

What are the three steps for formation of bile?

Answer 43

Secretion of bile into bile canals (canaliculi). Intrahepatic ducts secrete water bicarb rich fluid. B/w meals about 1/2 of hepatic bile is diverted to the gall bladder, which stores bile and removes salts and water

Question 44

What volume to the first two steps of bile formation produce?

Answer 44

Around 900 mL/day or so called "hepatic bile"

Question 45

What is the result of diverting bile to the gall bladder?

Answer 45

Gall bladder concentrates the key remaining solutes - bile salts, bilirubin, cholesterol and lecithin by 10-20 fold

Question 46

During meals the bile that reachs the duodenum is relatively what?

Answer 46

Dilute hepatic bile and concentrated gall bladder bile

Question 47

What are the two important functions of bile?

Answer 47

Provides sole excretion route for many solutes that are not excreted by the kidneys. Secreted bile salts and lecithin are required for normal lipid digestion and absorption in small intestine