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d1 fall histology > 11/16: Accessory Digestive Organs > Flashcards

11/16: Accessory Digestive Organs Flashcards

1
Q

What are the major functions of the liver?

A
  • Detoxification of metabolic waste (e.g., deamination of AA’s –> urea)
  • Metabolism & detoxification of drugs & toxins (e.g., alcohol,
    antibiotics)
  • Destruction of senescent RBC’s
  • Recycling of Hb via synthesis & secretion of bile
  • Synthesis of plasma proteins (clotting factors, albumin,
    lipoproteins)
  • Miscellaneous metabolic functions (fat, carbohydrate,
    proteins, etc.)
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2
Q

How do the products of digestion enter the liver via?

A

Hepatic portal vein

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3
Q

What percent of blood is carried to the liver via the hepatic portal v?

A

75-80%

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4
Q

What else does the hepatic circulation carry?

A

potentially toxic compounds absorbed from diet to liver to be conjugated or detoxified

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5
Q

How is oxygenated blood supplied to the liver via?

A

Hepatic artery, a branch of celiac trunk

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6
Q

What does the hapatic artery split into?

A

R/L hepatic Aa in hepatic lobules

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7
Q

What percent of blood does the hepatic artery carry?

A

20-25% of blood to liver

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8
Q

What does the hepatic artery blood mix with?

A

UNoxygenated blood from portal V to perfuse liver cells

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9
Q

Describe the liver in regardes to nutrients and O2

A

Nutrient rich, but O2 poor environment

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10
Q

What is the venous drainage via?

A

Lobules via central vv -> hepatic v -> IVC

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11
Q

What are the cells found in the liver?

A

Hepatocytes
Endothelial cells
Kupffer cells
Stellate cells (Ito cells)

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12
Q

What is the main functional cell?

A

Hepatocytes

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13
Q

How are hepatocytes arranged?

A

In plates or cords around sinusoids

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14
Q

Where are endothelial cells found?

A

Line the sinusoids

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15
Q

What are liver-specific macrophages?

A

Kupffer cells

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16
Q

What cells store vitamin A?

A

Stellate cells (Ito cells)

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17
Q

What is the structure of hepatocytes?

A

Diploid, but some polyploid or binucleate

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18
Q

What do hepatocytes contain?

A

Large #s of cytoplasmic granules (rER and lysosomal products) and storage products

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19
Q

What do aging hepatocytes accumulate?

A

Brown pigment, lipofuscin

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20
Q

Describe the structure and arrangement of individual hepatocytes

A

polygonal, arranged in anastomosing cords

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21
Q

What are hepatocytes paralleled by?

A

Venous sinusoids

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22
Q

What are sinusoids lined by?

A

Sinusoidal lining cells, a discontinuous endothelium, with gaps between endothelial cells

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23
Q

What are hepatic cords and sinusoids supported by?

A

Meshwork of reticulin fibers (Type III collagen)

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24
Q

What is found within sinusoids and space of disse?

A

Phagocytic Kupffer cells

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25
Q

What is occasionally between hepatocytes?

A

Stellate or Ito cells

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26
Q

What are stellate or Ito cells?

A

fat- storing cells containing lipid droplets, used for Vit A & D, storage

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27
Q

Describe the cytoplasm of a kupffer cell

A

Packed with black carbon particles

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28
Q

How can Kupffer cells be recognized?

A

by their oval nuclei closely associated with sinusoidal spaces

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29
Q

Describe the appearance of endothelial cells

A

Similar to kupffer, but with thinner (flatter) and denser
nuclei and with less conspicuous cytoplasm

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30
Q

What do hepatocytes that comprise the hepatic cords have?

A

Round nuclei surrounded by abundant cytoplasm

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31
Q

What is the function of Kuppfer cells?

A

remove foreign particles, they also work with the spleen to destroy old RBCs

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32
Q

What happens to a stellate cell in liver injury?

A

Becomes a transitional cell or
myofibroblast-like cellW

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33
Q

What is the function of a stellate cell in liver injury?

A

capable of synthesising collagen types I, III and IV as well as lamini

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34
Q

What is a thin, discontinuous, highly fenestrated endothelium that does not rest on a basement membrane?

A

Hepatic sinusoids

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35
Q

What are hepatic sinusoids separated from the hepatocytes by?

A

The space of Disse or the perisinusoidal space

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36
Q

Where are hepatic sinusoids found?

A

In the liver between a hepatocyte and a sinusoid

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37
Q

What do hepatic sinusoids contain?

A

Blood plasma

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38
Q

Where do microvilli of hepatocytes exten?

A

Into the hepatic sinusoids

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39
Q

What does the extension of microvilli allow for?

A

Proteins and other plasma components from the sinusoids to be absorbed by the hepatocytes

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40
Q

What kind of vascular channels are found within hepatic sinusoids?

A

Low resistance that allow blood to come into contact with hepatocytes over a large surface area

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41
Q

What is the flow of bile made by?

A

Hepatocyte & secreted into bile canaliculi between cells

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42
Q

What are the 3 concepts of liver lobules?

A

Classic hepatic lobule
portal lobule
Hepatic acinus of rappaport

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43
Q

What is the organization of hepatic lobules?

A

Cords of hepatocytes arranged in lobules

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44
Q

What is a classic lobule?

A

Based on blood flow; roughly hexagonal, with central vein in middle of lobule

45
Q

What is the outer margin of each lobule delimited by?

A

Thin, connective tissue septum

46
Q

What is located at each “corner” of a classic lobule?

A

Portal tracts/triads

47
Q

What do portal tracts/triads contain?

A

Hepatic A, br. portal V, L, and bile duct

48
Q

How does blood enter from portal tracts, percolates through?

A

Sinusoids of lobule

49
Q

What drains portal tracts?

A

Central vein

50
Q

What is a triangular area; based on bile flow (opposite to blood flow)?

A

Portal lobule

51
Q

What makes up a portal lobule?

A

Portal triad in center and central vv at corners

52
Q

What is an acinus?

A

Diamond shaped region between neighboring central vv

53
Q

Where are central vv located in hepatic acini?

A

Along longitudinal axis with portal tracts at sides

54
Q

What aspects make up the hepatic ascini?

A

Blood flow, oxygenation, metabolism and pathology

55
Q

What is an acinus divided into?

A

3 zones - 1,2,3

56
Q

What do hepaticytes in different zones have?

A

Different metabolic environments

57
Q

Describe the 3 zones of the hepatic acini

A

Zone 1—(perilobular zone = periportal)— closest to portal tract
Zone 2—(intermediate zone)
Zone 3—(centrolobular zone)—furthest from portal tract, closest to central V

58
Q

What receives most oxygenated blood;
also most susceptible to toxic injury?

A

Zone 1

59
Q

What receives least oxygenated blood; most
susceptible to ischemic injury?

A

Zone 3

60
Q

How does the liver function in detoxification or metabolism of drugs, toxins, metabolites?

A

Via microsomal mixed function
oxidase system of sER, or peroxidases of peroxisomes (P450 system)

61
Q

What is cirrhosis characterized by?

A

hepatic degeneration & necrosis, followed by fibrosis & nodular regeneration

62
Q

What is associated
with cirrhosis (due to fibrosis,
blockage of blood flow)?

A

Portal hypertension

63
Q

Does the liver have the ability to regenerate?

A

Yes

64
Q

What is the muscular sac located in depression
along surface of liver?

A

Gallbladder

65
Q

What is the gallbladder used for?

A

Store & concentrate bile;
volume ~100 ml

66
Q

What is the gallbladder lined by?

A

Simple columnar epithelium
with apical microvilli

67
Q

What is the microvilli in the gallbladder used for?

A

Resorption of water

68
Q

What does the gallbladder lack?

A

A muscularis mucosae

69
Q

What is the lamina propria highly folded with?

A

Occassional tubuloalceolar mucus glands

70
Q

What stimulates contraction of gallbladder?

A

CCK (Cholecystokinin)

71
Q

What are components of bile?

A

Water, ions, electrolytes, cholesterol + phospholipids (= lecithin), bile acids (= bile salts) & bile pigments

72
Q

What is the best known bile pigment?

A

Bilirubin

73
Q

What is the non-sol breakdown product of Hb

A

Bilirubin

74
Q

What happens in a failure to absorb bilirubin or failure to conjugate it and secrete?

A

accumulation of bile
pigments & jaundice

75
Q

What does supersaturation of bile cause?

A

Gallstones (biliary calculi, cholelithiasis)

76
Q

What does obstruction of bile ducts (choledocolithiasis) cause?

A

Bile stasis, or jaundice (icterus) if severe

77
Q

What is chronic inflammation of the gallbladder?

A

Cholecystitis

78
Q

What is the removal of the gallbladder?

A

Cholecystectomy

79
Q

What happens following a cholecystectomy?

A

unable to concentrate bile; need to limit ingestion of fats

80
Q

What is a highly lobulated gland with thin, connective tissue capsule, located in bend of duodenum?

A

Pancreas

81
Q

What components does the pancreas have?

A

Endocrine and exocrine

82
Q

Where is ductless endocrine pancreatic tissue located?

A

In islets of langerhans

83
Q

Most of the pancreas is ______

A

Exocrine (i.e. with ducts) - a compound, acinar, serous gland

84
Q

What is densely packed in the pancreas?

A

Serous acini contain pyramidal secretory cells surrounding a central lumen (duct)

85
Q

What do acinar cells contain?

A

Zymogen granules (inactive enzyme precursors)
e.g., trypsinogen (=
protrypsin),
chymotrypsinogen (=
prochymotrypsin),
amylase, lipase

86
Q

What are proteases?

A

Trypsin and chymotrypsin

87
Q

What breaks down carbohydrates?

A

Amylase

88
Q

What do lipases digest?

A

Lipids

89
Q

Where do the secretory acini empty into?

A

Intercalated ducts

90
Q

What can intercalated ducts differentiate into?

A

Add bicarbonate and water to pancreatic sections; neutralize acidic chyme from stomach -> optimal pH for pancreatic enzymes

91
Q

What forms the beginning of intercalated ducts?

A

Duct cells

92
Q

What is sometimes visible in the center of acini?

A

Centro-acinar cells

93
Q

Where do intercalated ducts empty into?

A

Larger intralobular ducts

94
Q

Where do intralobular ducts exit into?

A

Interlobular (=extralobular) ducts

95
Q

How do pancreatic secretions enter the duodenum?

A

Via pancreatic duct at major duodenal papilla

96
Q

What are the principle regulators of exocrine pancreas?

A

Polypeptide hormones secreted by enteroendocrine (APUD) cells

97
Q

What is primarily secreted by stomach?

A

Gastrin

98
Q

What secretes gastrin?

A

G cells of pyloric stomach

99
Q

What does gastrin do?

A

Stimulates secretion of pancreatic fluid

100
Q

What 3 things are secreted by duodenum?

A

Secretin
CCK
Enterokinase

101
Q

What is secretin secreted by?

A

S cells

102
Q

What does secretin do?

A

stimulates secretion of bicarbonate by cells of intercalated ducts

103
Q

What is CCK (Cholecystokinin = pancreozymin) secreted by?

A

I cells

104
Q

What does CCK do?

A

Stimulates acinar cells to secrete zymogen

105
Q

What does enterokinase do?

A

converts trypsinogen -> trypsin (within small intestine), which converts chymotrypsinogen -> chymotrypsin (digests proteins)

106
Q

What prevents the pancreas from digesting itself?

A

Cascade rxn

107
Q

What is an autodigestion of pancreas brought on by alcoholism?

A

Pancreatitis

108
Q

What does the cascade rxn break down?

A

Premature conversion of chymotrypsinogen to chymotrypsin & autolysis

109
Q

Is severe, acute pancreatitis fatal?

A

Yes within hours

d1 fall histology (20 decks)

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