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elimination and detox wk 1 > liver structure and function > Flashcards

liver structure and function Flashcards

1
Q

what is the largest gland in the body

A

liver

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2
Q

what percent of blood flow does the liver recieve

metabolically active

A

28%

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3
Q

what percent of O2 does the liver extract

A

~20% of O2 used by body

highly aerobic

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4
Q

what are the two blood supplies of the liver

A
  • hepatic artery (25%, oxygenatied, nutrient poor)
  • portal vein (75%, deoxygenated, nutrient rich)
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5
Q

how does blood exit the liver (through which vessel)

A

hepatic vein

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6
Q

all blood from GI tract and spleen flow through the liver by which vessel

A

portal vein

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7
Q

what are congenital portosystemic shunts

A
  • some blood from portal vein bypasses liver
  • intrahepatic shunt
  • extrahepatic shunt
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8
Q

what occurs in animals that have congenital liver shunts

A
  • not be able to efficiently metabolize nutrients from the gut
  • small in stature, and/or poor growth
  • otherwise healthy ot have V/D or PU/PD
  • develop hepatic encephalopathy due to high ammonia levels w/ ammonium urate stones in urinary tract
  • slow to metabolize and recover from drugs
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9
Q

what do hepatocytes do

A
  • ~80% liver vol.
  • synthesis of proteins, carbs, lipids, metabolism and detox
  • produce bile that drains into small bile canaliculi between adjacent hepatocytes
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10
Q

what are the other cell types of the liver

6% of liver cells

A
  • endothelial cells
  • Kupffer cells
  • Stellate cells
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11
Q

what are kupffer cells

A
  • resident macrophages inside sinusoids
  • remove particulates from blood
  • part of reticuloendothelial system
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12
Q

what are stellate cells

A
  • located in perivascular space (space of disse)
  • contain large lipid droplets
  • play key role in VA storage
  • capable of forming proliferative myofibroblasts (fibrogenic)
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13
Q

what is the functional unit of the liver

A

lobule (hexagonal)

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14
Q

what is a lobule

A
  • cords of hepatocytes surrounded by sinusoidal capillaries
  • portal tract
  • central collecting vein
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15
Q

what makes up the portal tract

A
  • hepatic artery
  • portal vein
  • bile duct

(lymphatic vessel also here)

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16
Q

what is the main cell type in the liver lobule

A

hepatocyte

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17
Q

what is the exocrine function of the liver

A

produce bile, which drains into small bile canaliculi adjacent to the hepatociles

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18
Q

what do bile canaliculi collect into and then drain into

A

collect into larger collecting bile ducts, drain into the common bile duct empyting into the duodenum

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19
Q

how does blood leave the lobule and leave the liver

A

blood leaves lobule through central collecting veins, and ultimately leaves liver through the hepatic vein

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20
Q

what is the purpse of the microvilli on the hepatocytes

A
  • project into the space between the hepatocyte and the hepatic sinusoid
  • help absorb substances from the blood and aid in the secretion of plasma proteins
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21
Q

the liver is a key…

A

frontline immune tissue

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22
Q

what do kupffer cells play a role in

A

pathogenesis of chronic and acute alcohol-related liver disease ALD

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23
Q

what can activated kupffer cells produce

A

large amount of ROS, pro-inflammatory cytokines, chemokines (may contribute to liver injury)

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24
Q

in a healthy liver, hepatic stellate cells are considered to be:

A

quiescent

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25
Q

what do hepatic stellate cells contain

A

numerous VA lipid droplets, contituting the larges reservoir of VA in the body

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26
Q

what happens during liver injury to stellate cells

A

they transform into activated myofibroblast-like cells to generate scar tissue

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27
Q

what happens in chronic liver disease/prolonged activated of hepatic stellate cells

A

prolonged activation of hepatic stellate cells causes liver fibrosis as characterized by widespread scar formation

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28
Q

what is cirrhosis

A

scarring damage is irreversible

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29
Q

liver regeneration

A
  • remarkable regenerative capacity
  • healthy liver: partial hepatectomy (70%) of a leads to compensatory regenerative growth
  • restoration of organ size in a mater of days
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30
Q

bile production is

A

one of the main functions of the liver

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31
Q

what is bile produced by and secreted into and stored

A

hepatocytes, bile canaliculi, gallbladder

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32
Q

what is bile comprised of

A
  • bile acids
  • cholesterol
  • elecrolytes
  • bilirubin and biliverdin
  • glibulins
  • water
  • lecithin, amino acids, drugs, heavy metals, vitamins, also some hormones, proteins and peptides
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33
Q

what is the function of bile in digestion

A

emulsification of fat/oils - aids in digestion/absorption

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34
Q

what is the functionof bile in absorption of fat and fat-soluble vitamins

A

biliary tract pathology may result in a decrease in the absorption of fat and fat soluble vitamins

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35
Q

what is the function of bile in elimination (mostly via feces)

A
  • excess cholesterol
  • lipid-soluble metabolites, drugs
  • heavy metals
  • bilirubin
  • other toxicants
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36
Q

what does enterohepatic recycling influence

A

elimination times of some drugs and metabolites

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37
Q

what increases solubility of molecules

A

hydroxylation modifications

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38
Q

what does amphipathic mean

A

molecule is both hydrophobic and hydrophilic (aids in bile acids ability to emulsify fats)

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39
Q

what do bile acid conjugation reactions do

with glycine and taurine

A

they are within hepatocytes and increase bile acid solubility in water and enhances their ability to emulsify lipids

40
Q

what are bile salts

A

bile acids associated with Na+ or K+ ions

41
Q

what do bile acids and salts facilitate

A

the absorption and/or elimination of lipophilic/hydrophobic molecules (such as cholesterol)

42
Q

bile salt pathologies

A

due to lack of bile salts or other bile ingredients

43
Q

gall stones

A

bile salts keep the cholesterol in a soluble form in the gallbladder, which prevents the formation of gallstones

44
Q

vitamin deficiencies

A

bile helps in the digestion of fats and oils, this are essential for hormone production, storage of the fat-soluble vitamins A, D, E, K, cellular membrane homeostasis

45
Q

GI issues

A

bile salts help promote intestinal motility, which allows defecation

46
Q

bile malabsorption pathologies

A
  • when bile salts cannot be reasorbed in the intestine
  • as bile salts attract water molecules, the first symptom is watery diarrhea
  • can be an acute or chronic condition, and is often associated with irritable bowel syndrom, crohn’s disease, and celiac disease
47
Q

bilirubin production via:

A

reticuloendothelial system

48
Q

old or damaged RBC are removed by:

A

macrophages in the spleen, liver (kupffer cells) and bone marrow

49
Q

what is the filtration function of kupffer cells

A
  • remove particulates from blood
  • eliminates senescent blood cells and foreign bodies
50
Q

how is bilirubin produced and eliminated

A
  • RBCs accumulate oxidative injury, which exposes antigens recognized by macrophages
  • macrophages convert hemoglobin into biliverdin and then to unconjugated bilirubin
  • macrophages export the unconjugated bilirubin into blood, where it binds to serum albumin
  • small amounts of bilirubin also come from metabolism of other heme-containing proteins - myoglobin
51
Q

bilirubin elimination via:

A

hepatocytes and bile

52
Q

unconjugated bilirubin is transported within the hepatocyte by ligand or Z protein and conjugated to ____ to form ____ to increase ____

A

glucuronic acid; conjugated bilirumin (BG); water solubility

53
Q

~10% urobilinogen undergoes ____ via portal vein

A

enterohepatic recirculation

54
Q

icterus

A

excess amounts of bilirubin in the bloodstream causes icterus - the yellow discoloration of the skin and mucous membranes that can occur with liver disease

55
Q

if bilirubin excretion is compromised….

A

there will also be lightly colored stool

56
Q

cholestasis

A

any condition in which the flow of bile from the liver to duodenum stops or slows

57
Q

what can cholestasis be caused by

A
  • gallbladder obstriction, gall stones
  • bile duct obstruction, narrowing of bile ducts, bile duct tumor
  • liver infection
  • cancer
  • genetic defects affecting bile acid synthesis
  • liver dysfunction: defective phase II enzymes, such as glucuronyl transferase
58
Q

what are symptoms of cholestasis

A

itching, dark urine, light colored bowel movements

59
Q

what are the blood related functions of the liver

A
  • removes old or damaged RBC from the circulation
  • breaks down hemoglobin
  • iron storage
  • synthesizes many serum proteins
  • synthesizes blood coagulation proteins
60
Q

most of the iron that enters the liver is derived from plasma and is bound to:

A

tansferrin

61
Q

what is iron taken up by

A

hepatocytes via transferrin receptors 1 and 2

62
Q

iron is stored in liver cells in

A

ferritin

63
Q

hepatocytes release iron via the plasma membrane iron exporter:

A

ferroportin 1 (FPN)

64
Q

what inhibits iron release through its interaction with the iron export ferroportin

A

hepcidin (produced in liver)

65
Q

dietary iron is absorbed by duodenal enterocytes and exported to blood via

A

ferroportin (FPN) iron exporter

66
Q

iron from senescent erythrocytes is:

A

recycled by macrophages and liver kupffer cells and exported into plasma via FPN exporters

67
Q

mobilization of iron is negatively regulated by the

A

liver hormone hepcidin

68
Q

what is hepcidin

A

liver peptide hormone

69
Q

what do high serum iron levels promote

A

hepatocyte hepcidin expression and release

70
Q

what does chronic liver disease cause

A

anemia

71
Q

what is the main protein produced by the liver

A

albumin

72
Q

what are the functions of albumin

A
  • maintenance of fluid pressure in arteries and veins
  • carry the other compounds through the bloodstream
73
Q

fluid leaked from vessels is called ____ when it occurs in the abdominal cavity

A

ascities

74
Q

fluid leaked from vessels is called ____ when it occurs in the thoracic cavity

A

pleural effusion

75
Q

what is the “pulling power” called

A

oncotic pressure

76
Q

what is hypoproteinemia

A

decreased plasma protein concentration - common cause of edema

77
Q

what are the causes of hypoproteinemia

A
  • decreased rate of plasma protein production by the liver - during liver failure or malnutrition; abdomen is grossly distended by edema and ascities
78
Q

hepatocytes synthesize most blood coagulation factors:

A

prothrombin, fibrinogen, factor V, VII, IX, XI, XII, protein C and S, and antithrombin

79
Q

liver sinusoidal endothelial cells:

A

factor VIII and von Willebrand factor

80
Q

vitamin K

A
  • important for clottin factor synthesis
  • bile salts important for VK absorption
  • stored in hepatocytes
  • anti-coagulation rat poinsons interfere with VK function - causing bleeding
  • liver failure can cause severe bleeding problems
81
Q

what vitamins are stored in the liver

A
  • lipid-soluble vitamins (A, D, E, K)
  • vitamin B12
82
Q

vitamin A is stored in

A

hepatic stellate cells lipid droplets as retinyl ester

83
Q

what is active retinol converted to

A

retinyl ester by lecithin: retinol acyltransferase

84
Q

what are the functions of VA

A
  • formation of the photoreceptor rhodopsin
  • signaling molecule within gene transcription
  • normal function of the immune system
  • mobilization of iron stores for RBC production
85
Q

what is cholecalciferol

A

VD produced in the body

86
Q

what does the liver store

A

glycogen, lipid, vitamin, minerals, and other sever as buffers to prevent the adverse consequences of insufficient or excessive dietary intake

87
Q

what is glycogenesis

A

hepatocytes convert excess glucose into glycogen

88
Q

what is glycogenolysis

A

stored glycogen is converted back into glucose and relesed into the body to supply energy

89
Q

where also can the liver manufacture glucose from

A

protein or fats

90
Q

in liver disease, the body can have a difficult time regulating blood glucose levels, usually leading to ____

A

hypoglycemia

91
Q

how are triglycerides created

A

from excess glucose when carbohydrate intake exceeds the normal glycogen storage

92
Q

what is fatty liver syndrome (lipidosis)

A

consequence of anorexia; fat is broken down rapidly tp supply energy and nutrients - FA’s overwhelm liver’s ability to process them

93
Q

what is hepatic steatosis (fatty liver)

A

infection, inflammation, obestity, poor dietary habits, drug toxicity, alcohol liver disease, fatty liver syndrome, food additives

94
Q

what are fatty acids oxidized into

A

acetyl-CoA

95
Q

what can fatty acids in cells be esterified into

A

triglycerides that are excreted from the liver

elimination and detox wk 1 (5 decks)

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