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Cardiovascular, Pulmonary, and Hepatic Physiology > Hepatic Physiology > Flashcards

Hepatic Physiology Flashcards

1
Q

what is the heaviest gland in the body and how large is it in the avergae adult?

A

liver; about 3lbs

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2
Q

where is the liver located?

A

inferior to the diaphragm

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3
Q

what are the two sections of the liver? what divides them?

A

right and left lobes; divided by the falciform ligament

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4
Q

what is the falciform ligament?

A

a fold of mesentery that divides the right and left lobes of the liver

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5
Q

what is the gallbladder? where is it located? what is its function?

A

a pear shaped sac located in the depression of posterior surface of the liver that stores bile

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6
Q

what are 13 functions of the liver?

A
  1. filtration and storage of blood
  2. metabolism of carbohydrates, proteins, and fats
  3. detoxification/degradation of body wastes, hormones, drugs, and foreign compounds
  4. plasma protein synthesis
  5. storage of glycogen, fats, iron, copper, and many vitamins
  6. activation of vitamin D
  7. removal of bacteria and worn-out red blood cells
  8. excretion of cholesterol and bilirubin
  9. synthesis of ascorbic acid (vitamin C)
  10. bouyancy in sharks
  11. gluconeogenesis
  12. lipogenesis for yolk
  13. formation of bile
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7
Q

what is the basic functional unit of the liver? (the less preferred way to view it)

A

the liver lobule

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8
Q

what is a liver lobule?

A

hexagonal arrangement of tissue surrounding a central vein

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9
Q

what 3 vessels are on the outer edge of the liver lobule? what do these three vessels form?

A
  1. branch of hepatic artery
  2. branch of portal vein
  3. bile duct
    THE HEPATIC TRIAD
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10
Q

what do the central veins of all liver cells converge to form?

A

the hepatic vein

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11
Q

what is the function of the hepatic vein?

A

carries blood away from the liver

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12
Q

what are the two sources from which the lvier receives blood?

A
  1. arterial blood
  2. venous blood
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13
Q

describe blood flow between the liver, the GI tract, and the heart (4)

A
  1. the liver receives blood from arterial blood and venous blood
  2. arterial blood provides the liver’s O2 supply and carries blood-borne metabolites for hepatic processing and is delivered by the hepatic artery
  3. venous blood draining the GI tract is carried by the hepatic portal vein to the liver for processing and storage of newly absorbed nutrients
  4. blood leaves the liver via the hepatic vein
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14
Q

how does blood get to the liver?

A

the hepatic artery and portal vein drain into sinusoid capillaries, which drain into the central vein, which will drain into the hepatic vein

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15
Q

what do hepatocytes do in the liver lobule?

A

continuously secrete bile into bile canaliculis

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16
Q

what do bile canaliculis do in the liver lobule?

A

carry bile to the bile duct

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17
Q

what do bile ducts from various liver lobules converge to form? what is its function?

A

the hepatic duct, which transports bile from the liver to the duodenum

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18
Q

what is the preferred view of the structural and functional unit of the liver? describe

A

the hepatic acinus, which is an oval mass thta includes portions of 2 neighboring hepatic lobules

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19
Q

how is the hepatic acinus divided?

A

into 3 zones

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20
Q

describe the cells of zone 1 of the haptic acinus (4)

A
  1. cells are closest to branches of the hepatic portal triad
  2. these cells are the first to receive incoming O2, nutrients, and toxins
  3. these cells are the first to show morphological changes following bile duct obstruction of toxin exposure
  4. these cells are the last to die if circulation is impaired
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21
Q

describe the cells in zone 3 of the hepatic acinus

A
  1. these cells are farthest from the branches of the protal triad
  2. these cells are the last to show effects of bile obstruction or toxin exposure
  3. these cells are the first to show effects of impaired circulation
  4. these cells are the last to regenerate
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22
Q

describe the blood flow and vascular resistance of the liver

A

the liver has high blood flow and low vascular resistance

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23
Q

what percent of resting cardiac output does the liver receive? why?

A

27% because it is responsible for so many metabolic processes

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24
Q

what 2 conditions caused increased vascular resistance in the liver?

A
  1. liver cirrhosis
  2. portal hypertension
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25
Q

what is cirrhosis of the liver?

A

destroyed liver parenchymal cells are replaced with fibrous tissues which contracts around the blood vessels

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26
Q

what are 3 causes of liver cirrhosis? what links these causes together?

A
  1. alcoholism
  2. poisoning
  3. viral diseases
    all cause release of proinflammatory cytokines
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27
Q

describe portal hypertension (4)

A
  1. large clot blocks portal vein or one of its major branches
  2. flow of blood from the intestines and spleen through liver portal system is impeded
  3. increased capillary pressure in intestinal walls results in loss of fluids
  4. death can occur within a few hours
28
Q

what percent of the body’s blood volume does the liver normally contain?

A

about 10%

29
Q

when would the liver expand to hold extra blood and how much extra can it hold?

A

if the right side of the heart malfunctions and blood builds up on the systemic side of circulation, the liver can expand to hold up to 1 liter of blood

30
Q

when the liver contracts, what happens to blood volume in circulation?

A

liver contracts to increase blood volume in circulation

31
Q

describe the lymph flow of the liver

A

very high; about half of lymph formed under resting conditions arises from the liver

32
Q

when hepatic venous pressure increases, what happens in terms of the lymphatic system?

A

excessive fluid moves into lymph and begins to leak through the outer surface of the liver into the abdominal cavity (“sweating”)

33
Q

what can “sweating” from the liver surface result in? what is this condition called?

A

can cause large amounts of free fluid in the abdominal cavity; called ascites

34
Q

after what percent hepatectomy can the liver restore itself? what must be present for regeneration to occur?

A

can restore itself after up to 70% tissue loss as long as some healthy tissue remains

35
Q

how is liver regeneration stimulated?

A

by hepatocyte growth factor

36
Q

where is hepatocyte growth factor produced? what is its function?

A

prpduced in mesenchymal cells in the liver; important factor in liver cell division and growth

37
Q

apart from hepatocyte growth factor, list 3 other factors involved in liver tissue regeneration

A
  1. epidermal growth factor
  2. tumor necrosis factor
  3. interleukin-6
38
Q

what inhibits liver regeneration? (liver cell proliferation)

A

transforming growth factor beta

39
Q

what does stimulation and inhibition of liver regeneration maintain?

A

maintains optimal liver to body weight ratio

40
Q

what 3 conditions can impair the liver regenerative process?

A
  1. fibrosis
  2. inflammation
  3. viral infections
41
Q

list the 2 aspects of the blood cleansing function of the liver

A
  1. blood from intestinal capillaries picks up bacteria
  2. Kupffer cells engulf
42
Q

what are Kupffer cells? what do they do?

A

large, phagocytic macrophages that line hepatic venous sinuses; engulf bacteria quickly when they come into contact with bacteria

43
Q

what are the 4 aspects of the carbohydrate metabolism function of the liver?

A
  1. storage of large amounts of glycogen
  2. conversion of galactose and fructose to glucose
  3. gluconeogenesis (when blood glucose and glycogen are low)
  4. formation of many chemical compounds from intermediate products of carbohydrate metabolism
44
Q

describe the liver’s glucose-buffer function

A

the liver is especially important in maintaining normal blood glucose concentrations (via carbohydrate metabolism)

45
Q

list the 3 aspects of the fat metabolism function of the liver

A
  1. oxidation of fatty acids (beta oxidation)
  2. synthesis of large quantities of cholesterol, phospholipids, and most lipoproteins
  3. synthesis of fat from protein and carbohydrates
46
Q

list the 4 aspects of the protein metabolism function of the liver?

A
  1. deamination of amino acids
  2. formation of urea
  3. formation of plasma proteins
  4. interconversions of various amino acids and synthesis of other compounds from amino acids
47
Q

what is deamination of amino acids? what does this form which must be converted to what?

A

removing the amino group which forms toxic ammonia that must be converted to urea

48
Q

what kinds of vitamins is the liver responsible for the metabolism of?

A

metabolism of fat-soluble vitamins

49
Q

what 3 vitamins can the liver store and for how long each?

A
  1. vitamin A: up to 10 month supply
  2. vitamin D: 3-4 month supply
  3. vitamin B12 (cobalamine): 1-several years supply
50
Q

how does the liver store iron?

A

the liver has large amounts of apoferritin, which reversibly binds with iron to form ferritin

51
Q

where are the first and second greatest proportions of iron in the body?

A

hemoglobin is greatest; ferritin is the second greatest (in the liver)

52
Q

what acts as a blood-iron buffer?

A

the liver

53
Q

what is the role of the liver in coagulation?

A

synthesizes multiple factors involved in coagulation

54
Q

what 4 coagulation factors does the liver synthesize? what is necessary for the synthesis of these factors?

A
  1. fibrinogen
  2. prothrombin
  3. accelerator globulin
  4. factor VII
    vitamin K is critical for the formation of these factors
55
Q

list the 3 aspects of the removal of drugs, hormones, and other substances from circulation function of the liver

A
  1. the liver can detoxify or excrete bile in the presence of many drugs such as penicillin and erythromycin
  2. many hormones and all steroid homrones are metabolized by the liver
  3. the liver is one of the major routes for excreting calcium
56
Q

what can liver damage result in in terms of hormones and why?

A

liver damage can result in accumulation of hormone in circulation since the liver metabolizes many and all steroid hormones

57
Q

what is bilirubin? (2)

A
  1. a greenish yellow pigment excreted in the bile
  2. product of metabolizing red blood cells
58
Q

what is bilirubin a valulable tool for?

A

diagnosing hemolytic blood diseases and various liver diseases

59
Q

describe the process bilirubin metabolism (4)

A
  1. the spleen breaks up old RBCs, splitting hemoglobin into heme, then to biliverdin, and then to unconjugated bilirubin
  2. unconjugated bilirubin passes to the liver, where it is conjugated and then passes into the GI tract
  3. in the GI tract, conjugated bilirubin is converted by bacteria to urobilinogen, some of which leaves in urine
  4. urobilinogen that does not leave in urine is reabsorbed into enterohepatic circulation and then oxidized to stercobilinogen, which is excreted in the feces
60
Q

what is the difference between unconjugated and conjugated bilirubin?

A

conjugated bilirubin is water soluble, unconjugated bilirubin is NOT water soluble

61
Q

what is jaundice? what is it also called?

A

jaundice/icterus is a yellowish tint due to large quantities of bilirubin in extracellular fluid

62
Q

what are the 2 types of jaundice?

A
  1. hemolytic jaundice
  2. obstructive jaundice
63
Q

describe hemolytic jaundice (2)

A
  1. increase in destruction of red blood cells causes
  2. free bilirubin in plasma to rise above normal
64
Q

what kind of bilirubin predominates in hemolytic jaundice?

A

unconjugated bilirubin

65
Q

describe obstructive jaundice, including the predominant bilirubin type (2)

A
  1. obstruction of bile ducts or damage to liver that prevents even normal amounts of bilirubin from being excreted
  2. most of bilirubin in plasma is conjugated
66
Q

what can obstructive jaundice cause? (3)

A
  1. absence or reduction of urobilinogen
  2. stoolslack stercobilin so will change to a lighter or clay color
  3. conjugated bilirubin in urine increases, which causes foam following shaking of a sample with intense yellow

Cardiovascular, Pulmonary, and Hepatic Physiology (12 decks)

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