3B Physiology of the Liver Flashcards

1
Q

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

A

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

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2
Q

Where does aa degradation occur almost entirely?

A

Liver

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3
Q

What two enzymes are required for deamination in the liver?

A

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

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4
Q

Where is essentially all urea synthesized in the blood?

A

Liver

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5
Q

What is a hepatic come or hepatic encephalopathy?

A

In serious liver disease, ammonia often accumulate in the blood

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6
Q

Where is urea excreted?

A

Kidneys

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7
Q

What is azotemia or uremia?

A

Toxic build up of urea in blood

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8
Q

What can cause an elevated BUN?

A

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

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9
Q

What is HMG-CoA-reductase?

A

important enzyme in liver hepatocytes required for endogenous cholesterol synthesis

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10
Q

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

A

Via bile

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11
Q

When does ketogenesis occur primarily?

A

Fasting states or poorly controlled type 1 diabetes

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12
Q

How does ketogenesis affect the pH of blood?

A

Lower pH (more acidic)

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13
Q

Does the liver degrade steroid hormones and T3 and T4?

A

Yes, sir!

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14
Q

What is hemachromatosis?

A

To much Fe+2 that begins to deposit in tissues

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15
Q

What does gastroferrin do?

A

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

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16
Q

What is transferrrin? Apoferritin? Ferritin?

A

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

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17
Q

The liver stores large quantities of what vitamins?

A

A, B12, and D

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18
Q

What is the purpose of metabolizing drugs?

A

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

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19
Q

Where are Cytochrome P450 enzymes most predominant?

A

Liver, intestines, lungs and other organs

20
Q

What are conjugation reactions designed to do?

A

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

21
Q

What is the most common and most important conjugation reaction?

A

Glucuronidation

22
Q

What is CP450 inhibition?

A

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

23
Q

What is CP450 induction?

A

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

24
Q

What stimulates Vitamin D activation in the liver?

A

PTH

25
Q

What are the major types of plasma proteins?

A

Albumin, globulin, fibrinogen

26
Q

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

A

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

27
Q

Which blood clotting factors are synthesized in the liver?

A

All but III, IV and XIII

28
Q

What is the composition of bile?

A

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

29
Q

Does bile contain water?

A

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

30
Q

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

A

Cholic acid and chenodeocycholic acid. Synthesized in the hepocytes

31
Q

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

A

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

32
Q

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

A

Glycine or taurine

33
Q

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

A

Makes the bile acids amphipathic at duodenal pH

34
Q

What is the most common phospholipid found in bile?

A

Lecithin

35
Q

Are phospholipids amphipathic?

A

Yes, sir!

36
Q

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

A

Bile

37
Q

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

A

500 mg

38
Q

What is the waste product of Hb degradation?

A

Bilirubin

39
Q

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

A

Attachmen of glucuronic acid to bilirubin.

Glucuronyl transferase

40
Q

Which type of bilirubin is more water soluble?

A

Conjugated bilirubin

41
Q

What cells secrete ions and water into the bile?

A

Ithelial cells lining the bile ducts

42
Q

What are other waste products that go into the bile?

A

Lipolithic drugs and metabolites, antigen-antibody complexes

43
Q

What are the three steps for formation of bile?

A

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

44
Q

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

A

Around 900 mL/day or so called “hepatic bile”

45
Q

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

A

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

46
Q

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

A

Dilute hepatic bile and concentrated gall bladder bile

47
Q

What are the two important functions of bile?

A

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