Physiology of Liver and Pancreas (Lec 14) Flashcards

1
Q

What are the two pathways of blood flow through the liver lobule?

A

portal vein -> sinusoids -> central vein -> hepatic veins

hepatic artery -> sinusoids ->central vein -> hepatic veins

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2
Q

Liver cell plates are composed of two layers of what?

A

hepatocytes

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3
Q

___ ___ lie between two layers of hepatocytes in each cell plate

A

bile canaliculi

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4
Q

Sinusoids are lined with what two types of cells?

A

endothelial cells and Kupffer cells

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5
Q

Where is space of Disse found?

A

between endothelial cells and hepatocytes

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6
Q

True or false?

Liver has low blood flow and high vascular resistance

A

false; high blood flow and low vascular resistance

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7
Q

In regards to liver vascular supply, 1050ml from portal vein + 300 ml from hepatic artery flows into ___ every minute

A

sinusoids

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8
Q

In regards to liver vascular supply, __% is resting cardiac output

A

27

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9
Q

Portal pressure into the liver = ___ mm Hg

A

9

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10
Q

Pressure form liver to vena cava = ___ mm Hg

A

0

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11
Q

What is the effect of cirrhosis on blood flow?

A

increases blood resistance to blood flow

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12
Q

What is the effect of clot blocking portal vein or a major branch of the liver?

A

blockage of return blood from spleen and intestines; increase in capillary pressure in intestinal wall -> loss of fluid -> death

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13
Q

In regards to liver vascular supply, what is the normal volume of the liver?

A

450 ml (10% of body’s blood volume)

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14
Q

High pressure in right atrium -> back pressure on liver -> increased blood volume in liver up to ___ liters

A
  1. 5

note: may occur during cardiac failure with peripheral congestion

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15
Q

True or false?

Liver can store blood in times of excess and supply blood in times of diminished volume

A

true

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16
Q

Hepatic sinusoids are highly permeable to what?

A

proteins

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17
Q

Efferent lymph has a protein concentration of __ g/dl

A

6 (almost equivalent to plasma concentration)

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18
Q

True or false?

There is a lower than normal pressure in hepatic veins

A

false; higher

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19
Q

Back pressure in the hepatic veins causes fluid to transude into ___

A

lymph

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20
Q

Fluid from the hepatic veins leaks through ___ __ into abdominal cavity

A

liver capsule

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21
Q

In regards to higher than normal pressure in hepatic veins, fluid is almost pure __

A

plasma

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22
Q

Large amount of fluid in abdominal cavity = ?

A

ascites

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23
Q

Carbohydrate metabolism is a function of the liver. Describe what carbohydrate metabolism does

A

stores glycogen; converts galactose and fructose to glucose; gluconeogenesis; forms many intermediate products

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24
Q

Oxidation of FAs for energy; synthesis of cholesterol, phospholipids, and lipoproteins; synthesis of fats from proteins and carbs are all aspects of what function of the liver?

A

fat metabolism

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25
Q

Protein metabolism is a function of the liver. Describe what occurs in protein metabolism

A

deamination of AAs; formation of urea; formation of plasma proteins; interconversion of various AAs and synthesis of other compounds from AAs

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26
Q

Vitamin storage is a function of the liver. What vitamins are stored in the liver?

A

Vitamin A; Vitamin D; Vitamin B12

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27
Q

True or false?

Immune function is a function of the liver

A

true

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28
Q

Fibrinogen; prothrombin; accelerator globulin; factors VII, IX, X are all aspects of what function of the liver?

A

formation of coagulation factors

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29
Q

Removal or excretion of drugs, hormones, and other substances is a function of the liver. Describe how the liver does this

A

detoxifies or excretes into the bile: sulfonamides, penicillin, ampicillin, and erythromycin; excretes calcium into the bile; detoxification and removal of ammonia and ethanol

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30
Q

Hepatic bile is ___ and ___ by the liver

A

produced; secreted

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31
Q

Bile from the ___ is hepatic bile that has been stored and concentrated

A

gallbladder

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32
Q

What are the components of bile?

A

bile acids, water and electrolytes, cholesterol and phospholipids, pigments and organic molecules

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33
Q

Cholic and chenodeoxycholic acids are bile acids. What are they synthesized by?

A

hepatocytes

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34
Q

Deoxycholic acid and lithocholic acid are bile acids. What are they converted by?

A

bacteria

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35
Q

What is the major pigment in bile?

A

bilirubin

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36
Q

In regards to bilirubin formation, first, hemoglobin is released by what?

A

damaged RBCs

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37
Q

In regards to bilirubin formation, hemoglobin is phagocytized by what?

A

macrophages

38
Q

In regards to bilirubin formation, hemoglobin is split into ___ and ___

A

globin; heme

39
Q

In regards to bilirubin formation, Heme ring is opened to free what?

A

iron

40
Q

In regards to bilirubin formation, heme is transported in the blood by what?

A

transferrin

41
Q

In regards to bilirubin formation, straight chain of ___ nuclei is formed

A

pyrrole

42
Q

In regards to bilirubin formation, heme is converted by ____ _____ into biliverdin

A

heme oxygenase

43
Q

In regards to bilirubin formation, biliverdin -> free ____

A

bilirubin

44
Q

In regards to bilirubin formation, free bilirubin is transported attache to ____ ___ to liver ____

A

plasma albumin; hepatocytes

45
Q

In regards to bilirubin formation, free bilirubin is released from plasma albumin within the liver cells and conjugated. Describe the break down of conjugation with glucoronic acid, sulfate, and other substances

A

glucuronic acid -> bilirubin glucuronids (80%)

sulfate -> bilirubin sulfate (10%)

variety of other substances (10%)

46
Q

Conjugated bilirubin is secreted (active transport) into what?

A

intestine

47
Q

Conjugated bilirubin in the intestine is converted by bacterial action into what?

A

urobilinogen

48
Q

Urobilinogen is oxidized into excreted products or:

A

reabsorbed into the blood and carried back to the liver

49
Q

If urobilinogen is carried back to the liver, what happens?

A

it can be re-excreted by the liver or excreted in the urine

50
Q

___ refers to a yellowish tint to the body tissues

A

jaundice

51
Q

What is jaundice caused by?

A

quantities of bilirubin in the extracellular fluids caused by increased hemolysis or obstruction of bile ducts or damage to liver

52
Q

What are the types of islet cells and what do they secrete?

A

alpha: secretes glucagon, 25% of total cells
beta: secretes insulin and amylin, 60% of total cells
delta: secretes somatostatin

53
Q

Insulin inhibits ___ secretion

A

glucagon

54
Q

Amylin inhibits __ secretion

A

insulin

55
Q

Somatostatin inhibits ___ and ___ secretion

A

insulin; glucagon

56
Q

Insulin circulates in unbound form in blood with a half-life of __ minutes

A

6

57
Q

What happens to Insulin not bounded to receptors?

A

destroyed by liver

58
Q

The following occur when what happens?
increased uptake of glucose; increased permeability to AAs, potassium, and phosphate ions; increased activity levels for many enzymes; changes in rates of translation and transcription

A

insulin binds to receptor

59
Q

How is insulin secreted?

A

beta cells in the islets of langerhans release insulin in two phases - rapid and slow

60
Q

Describe the structure of the insulin receptor

A

transmembrane receptor that belongs to the large class of tyrosine kinase receptors

61
Q

What happens to most of the glucose that is absorbed after a meal?

A

stored as glycogen in the liver

62
Q

In regards to the glucose uptake mechanism, insulin inactivated liver ____

A

phosphorylase

63
Q

In regards to the glucose uptake mechanism, insulin activates ___ and enhances uptake of glucose from __

A

glucokinase; blood

64
Q

In regards to the glucose uptake mechanism, insulin increases activities of enzymes needed for ___

A

glycogenesis

65
Q

In regards to events that cause liver to release glucose into blood, decreased blood glucose results in decreased ___ secretion

A

insulin

66
Q

In regards to events that cause liver to release glucose into blood, lack of insulin reverses what pathway?

A

glycogen synthesis

67
Q

In regards to events that cause liver to release glucose into blood, lack of insulin activates phosphorylase which does what?

A

splits glycogen into glucose phosphate

68
Q

In regards to events that cause liver to release glucose into blood, glucose phosphatase removes phosphate from glucose and allows it to what?

A

diffuse back into blood

69
Q

In regards to events that cause liver to release glucose into blood, insulin inhibits what?

A

gluconeogenesis

70
Q

What is insulin’s effect on fat storage?

A

Insulin promotes conversion of excess glucose into FAs and decreases utilization of fat

71
Q

In regards to effects on fat storage, insulin increases transport of ___ into liver creating excess

A

glucose

72
Q

In regards to insulin’s effect on fat storage, excess glucose is converted to what?

A

acetyl-CoA

73
Q

In regards to insulin’s effect on fat storage, FA synthesis is ___

A

initiated

74
Q

In regards to insulin’s effect on fat storage, newly synthesized FAs are converted into what?

A

Triglycerides and then transported form liver as lipoproteins

75
Q

In regards to insulin’s effect on fat storage, triglycerides split into fatty acids in ___ and are taken up into ___ cells

A

capillaries; fat

76
Q

In regards to insulin’s effect on fat storage, insulin promotes uptake of ___ by fat cells

A

glycerol

77
Q

In regards to effects of lack of insulin on fat storage, previous effects are reversed and large amounts of ___ and ___ are released into blood

A

glycerol; FAs

78
Q

Large amounts of acetoacetic acids are formed in the ___

A

liver

79
Q

In regards to effects of lack of insulin on fat storage, ___ transport mechanism in the liver is activated

A

carnitine

80
Q

In regards to effects of lack of insulin on fat storage, B-oxidation results in excess of ___

A

acetyl-CoA

81
Q

In regards to effects of lack of insulin on fat storage, excess acetoacetic acid causes ___

A

acidosis

82
Q

In regards to effects of lack of insulin on fat storage, increase of ___ bodies in blood

A

ketone

83
Q

The is an increase in plasma insulin concentration after increase in what?

A

blood glucose

84
Q

Break down of liver glycogen and increased gluconeogensis are the two major effects of what?

A

glucagon

85
Q

Describe the cascade of events leading to the major effects of glucagon

A

activates adenyl cyclase in hepatic cell membrane; cases formation of cAMP; activates protein kinase; activates phosphorylase b kinase; converts phosphorylase b into phosphorylase a; promotes degradation of glycogen to glucose-1-phosphate

86
Q

Somatostatin’s major effects are?

A

inhibits secretion of insulin and glucagon; decreases motility of stomach, duodenum, and gallbladder; decreases secretion and absorption of GI tract

87
Q

Increased osmotic pressure in extracellular fluid; loss of glucose in urine; osmotic diuresis; damage to tissues and blood vessels are effects of what?

A

negative effects of increased blood glucose levels

88
Q

This type of diabetes is due to lack of insulin secretion and injury to beta cells

A

Type I

89
Q

What causes Type II diabetes

A

insulin resistance, obesity, metabolic syndrome

90
Q

Obesity, insulin resistance, fasting hyperglycemia, increased lipid triglycerides, decreased HDL levels, hypertension are all symptoms of what?

A

metabolic syndrome