Liver, Gallbladder, and Pancreas Flashcards Preview

Histology > Liver, Gallbladder, and Pancreas > Flashcards

Flashcards in Liver, Gallbladder, and Pancreas Deck (127):
1

what are the extramural organs of the digestive system?

liver and pancreas

2

what organ is considered the digestive system's storage organ?

gallbladder

3

What are the endocrine functions of the liver?

synthesis and release of products into the blood (ie: plasma proteins)

4

what is the exocrine function of the liver?

production of bile

5

what is the largest gland in the body?

the liver

6

what is the parenchyma of the liver?

organized plates of hepatocytes separated by sinusoids

7

what type of tissue is found in the fibrous stroma of the liver?

type I collagenous tissue

8

what does the fibrous stroma of the liver do?

forms a thin capsule that surrounds vessels and ducts and provides some separation into lobules

9

what is the function of the reticular stroma? what type of tissue is found here?

provides a supporting network for the hepatocytes and sinusoids; formed by reticular fibers

10

What enters that the liver hilus? what exits?

blood vessels enter, bile duct exits

11

what percent of afferent blood is carried by the portal vein?

75%

12

what type of blood does the portal vein carry? what is it rich/poor in? where does the blood come from?

carries afferent blood that is rich in nutrients (and some potential toxins) but poor in oxygen;

it comes from the capillary beds of the intestines

13

What type of blood does the hepatic artery carry? what is it rich/poor in? where does the blood come from

carries afferent blood that is rich in oxygen;
comes from the left ventricle of the heart

14

what percentage of afferent blood is carried by the hepatic artery?

25%

15

Describe Hepatic blood flow:

1.Portal vein picks up blood from capillaries / hepatic artery gets blood from Left ventricle and carries it to:
2. Interloular branches
3. sinusoids
4. central vein
5. sublobular veins
6.Hepatic veins
7. Inferior vena cava
8. Right atrium

16

How does Bile exit the liver? where is it produced? how does it flow in relation to blood?

Bile is produced by the hepatocytes in the liver and flows out of the liver via a duct system that follows the arterial tree towards the hilus;
bile flows in the opposite direction as blood

17

Describe the anatomic/classic lobule

hexagonal lobules that contain radial arrays of plates of hepatocytes

18

what is each anatomic lobule centered around? what borders each corner?

centered around a central vein;
bordered at each corner by a portal canal (portal triad + CT)

19

What does a portal canal consist of?

portal triad + CT

20

what does a portal triad consist of?

interlobular branches of portal vein, hepatic artery, and bile duct

21

Where do the terminal branches of the portal veins and hepatic arteries run?

between lobules;

22

Where do terminal branches of the portal veins and hepatic arteries empty their blood into?

empty blood into sinusoids where the blood is mixed

23

Where do the hepatic sinusoid run? where do they carry blood to?

run between the plates of cells; carry blood to central vein (terminal hepatic venule)

24

what flows through the intercellular canaliculi? where does this substance flow after the intercellular canaliculi?

Bile;
flow: intercellular canaliculi -- canals of Hering -- interlobular bile ducts

25

what does the portal lobule center on?

the bile ductule

26

what does the portal lobule contain?

parts of 3 adjacent anatomic lobules, including any hepatocytes that supply bile to a particular bile ductule in the portal canal

27

What is a liver acinus? what is it's main focus? what is another name for the liver acinus?

its a functional lobule that focuses on the delivery of blood to hepatocytes;
aka "Rappaport's lobule"

28

is the liver acinus capsulated?

no

29

What is the liver acinus organized around?

an axis containing the terminal branches of the portal vein and hepatic artery

30

what does the liver acinus include?

any hepatocytes that are supplied with blood by a particular set of terminal branches that run between the two lobules

31

Describe how the hepatocytes receive blood in the Rappaport lobule

the cells in the center of the lobule (zone 1) are the first to receive oxygen, nutrients, and toxins; then Zone 2, then Zone 3 which is adjacent to the central vein

32

Which zone of the rappaport lobule is most prone to hypoxia?

zone 3; it is last to be affected by incoming agents and exposed to relatively low oxygen levels

33

where is the nuclei located in hepatocytes?

centrally

34

Are hepatocytes bincucleate? polypoid?

both!

35

What do hepatocytes border?

1. border on sinusoids with intervening space of disse into which microvilli project
2. Bile canaliculi

36

what are bile canaliculi? what are they formed/sealed by?

channels that are formed by the plasma membrane of adjacent hepatocytes and are sealed off by junctional complexes

37

what organelles/ inclusions are prominent in hepatocytes?

1. rER
2. sER
3. Golgi
4. lysosomes
5. peroxisomes
6. GLYCOGEN INCLUSION

38

can hepatocytes regenerate?

yes, but new cells do not establish proper relationships

39

What are the functions of the hepatocytes?

1. Synthesis of plasma proteins (by rER)
2. Detoxification of lipid soluble drugs/steroids
3. Fat Metabolism
4. Glycogen synthesis, storage, and release
5. Storage of iron
6. Metabolism of alcohol
7. Production of bile
8. Metabolism of vitamin A,D,E

40

What plasma proteins are produced by the rER of Hepatocytes?

albumin, fibrinogen, prothrombin, and coagulation factors

41

where are plasma proteins in the hepatocytes released?

into the space of Disse

42

How are lipid soluable drugs and steroids detoxified in hepatocytes?

hepatocytes transform nonpolar compounds into polar metabolites that can be eliminated by the kidneys

43

How are hepatocytes involved in Fat metabolism?

1. Chylomicra undergo lipolysis in the circular and deliver fatty acids to tissues, but the remnants are taken up by hepatocytes and metabolized. The fatty acids are esterified to triglycerides by the sER
2. some triglycerides are stored as fat droplets; most are coated with a mixture of proteins, cholesterol and phospholipids and are released in the plasma as VLDL (very low density lipid) particles

44

what organelles/cellular components are involved with glycogen synthesis, storage and release in hepatocytes?

sER and cytosol

45

What is iron stores as in hepatocytes

ferritin or hemosiderin granules

46

How is alcohol metabolized in hepatocytes?

through the alcohol dehydrogenase (ADH) pathway, producing acetaldehyde and acetate

47

what does chronic intake of alcohol active? what does this produce?

activates the microsomal ethanol oxidizing system (MEOS) which produces acetaldehyde and an excess of oxygen radicals. **Reactive oxygen damages hepatocyte plasma membranes

48

What materials do hepatocytes produce/release that are necessary for the production of bile? what do these material join to form bile?

cholesterol, phospholipids, bile salts, glucuronide conjugated bilirubin from the hepatocytes join electrolytes and metabolites of drugs and heavy metals into bile canaliculi as bile

49

What in canalicular plasma membrane mediates bile excretion?

specific ATP dependent transporters

50

What is bile secretion dependent on? is it continuous?

bile secretion is continuous; with the rate dependent primarily on blood flow to the liver

51

What happens to unused bile salts?

they get reabsorbed by enterocytes and returned to the liver via the portal vein to be reused by hepatocytes

52

What vitamins are metabolized by the hepatocytes?

A D E

53

What are hepatic sinusoids?

discontinuous capillaries that lack a continuous basal lamina

54

What cells form the lining of the sinusoid?

1. discontinuous endothelium (endothelial cells with large gaps)
2. Kupffer cells

55

What are Kupffer cells? what are they derived from? what is their function?

"sinusoidal macrophages"

they are resident phagocytic cells that are derived from monocytes and function in the breakdown of aged RBCs

56

where are Kupffer cells found?

line the hepatic sinusoid; but they may also span the sinusoidal lumen

57

what is the space of Disse?

perisinusoidal space that surrounds the sinusoid

58

Where is the space of Disse located?

between the plasma membrane of hepatocytes and basal surfaces of endothelial cells and Kuppfer cells

59

What does the Space of Disse contain?

1. microvillous projections of hepatocytes
2. a few reticular fibrers
3. Stellate cells

60

what are the hepatocyte's stellate cells? where are they located?

= lipocytes + cells of Ito
located within the space of Disse

61

what is the function of the hepatocytes's stellate cells?

store lipids and vitamin A
produce reticular fibers

62

What happens to stellate cells during liver cirrhosis?

they undergo trans-differentiation to myofibroblas-like cells and secrete large amounts of collagen and ECM into the space of Disse

63

Where is bile produced? secreted by? secreted into?

produced and secreted by hepatocytes into bile canaliculi

64

where do bile canaliculi course?

between hepatocytes within the lobule

65

Describe the flow of bile

1. Produced/secreted by Hepatocytes to
2. Bile canaliculi to
3. intraloular bile ductules (canal of Hering) to
4. interlobular bile ductules (within the portal canal)
5. to larger intrahepatic bile ducts to
6. R/L hepatic ducts
7. to common hepatic duct

66

what are the canals of Hering (intralobular bile ducts) lined by?

simple low cuboidal epithelium

67

what are the interlobular bile ductules lined by?

simple cuboidal epithelium as they collect bile, but then they increase in size are lined by columnar epithelium and are surrounded by increasing amounts of CT

68

what are the larger intrahepatic bile ducts lined by as the hilus is approached?

columnar epithelium and surrounded by dense fibroelastic CT and some smooth muscle

69

Describe the wall of the common hepatic duct

contains 4 layers: mucosa, submucosa, muscularis, and adventitia

70

where is most lymph formed in hepatocytes?

from the space of Disse

71

Describe the lymphatic flow in hepatocytes

lymph drains from the space of Disse to the periportal space of Mall to the lymphatic vessels (within the portal canals) to the larger vessels that parallel the bile passageways and leaves the liver

72

where is the periportal space of Mall located?

lies between the portal connective tissue and the hepatocytes at the border of the portal canal

73

What is the gallbladder?

distensible bag connected to the common bile duct via the cystic duct that concentrates and stores up to 50 mL of bile

74

Describe the surface of the gallbladder (empty and filled)

filled = smooth inner surface
empty = numerous folds or rugae

75

What type of epithelium is found in the mucosa layer of the gall bladder?

simple columnar epithelium with apical microvilli and junctional complexes and lateral interdigitations

76

what is the function of the lateral interdigitations of the mucosa layer of the gall bladder?

transport ATPase in the membranes pump Na +, Cl-, and HCO3- and water resorption

77

What are the diverticulae (Rokitansky-Aschoff crypts) of the gall bladder? where are they found?

found in the mucosa layer; the surface epithelium may be invaginated as deeply as the muscular layer forming diverticulae

78

Describe the Muscularis Externa layer of the Gall bladder

multiple layers of smooth muscle separated by networks of elastic fibers

79

Describe the serosa/adventitia layer of the gall bladder

broad layer of the CT containing blood vessels nerves and lymphatics

80

what are the functions of the gall bladder?

1. Store Bile
2. Concentrate bile by absorption of water
3. release bile during meal digestion

81

what are the layers of the gall bladder wall?

mucosa, muscularis externa, serosa/adventitia

82

How is bile concentrated in the gall bladder?

through the transepithelial transport of an isotonic fluid from the lumen to the vasculature:

ions (Na+) are pumped into intercellular lateral spaces and water follows

83

what happens to the interceullar spaces of the gall bladder when the bile is concentrated (active)

the intercellular spaces become distended in the active gallbladder (due to water being pumped into spaces with ions)

84

What is bile secretion stimulated by?

cholecystokinin (CCK) from the enteroendocrine cells in the duodenom

85

what does CCK do to the gall bladde?

induces contraction of its musculature and relaxation of the sphincter of oddi (sphincter of hepaticopancreatic ampulla)

86

How is the gall bladder different from the small I lamina propria?

GB: no mucosal glands
small I: mucosal glands are evident deep in the lamina propria (= intestinal glands = crpyts of Lieberkuhn)

87

How is the gallbladder different from the small I epithelium?

GB: 1. no goblet cells 2. microvilli not well developed

small I: 1. contain goblet cells 2. well developed microvilli (striated border)

88

What divide the pancrease into lobules? does it have a capsule?

no distinct capsule; delicate CT divides it into lobules

89

what cells carry out the exocrine function of the pancreas?

acinar cells

90

what cells carry out the endocrine function of the pancreas?

islets of Langerhans

91

What type of gland is involved with the exocrine function of the pancreas?

compound tubuloalveolar exocrine gland with serous alveoli

92

Describe the morphology and staining of pancreatic acinar cells (and why the areas stain the way they do)

= pyramidal cells that form a spherical acinus surrounding a lumen;

the basal (outer) cytoplasm is basophilic due to lots of rER
the inner = eos. due to accumulations of acidophlic zymogen granules in the apical cytoplasm; granules contain a mixture of pancreatic proenzymes

93

what enzymes are the pancreatic enzymes?

proenzymes including typsinogen + chymotrypsinogen

94

what is the function of the pancreatic enzymes?

when active they can hydrolyze most food

95

what is trypsinogen activated by? where?

by enterokinase in the glycocalyx of enterocytes

96

what is the result of activated trypsinogen?

= trypsin, which in turn activates other zymogen (inactive) enzymes

97

what is secrete from the pancreatic acinar cells?

proenzymes including typsinogen + chymotrypsinogen

also lipase and amylase

98

Describe the duct system of the acinar cells in the pancrease

1. intercalated ducts drain the acini
2. which drain into larger intercalated ducts
3. which drain into interlobular ducts

99

What drains the acini of the pancreas?

intercalated ducts

100

what is the epithelium found in the small intercalated ducts of the pancreas?

low simple cuboidal epithelium

101

what do the intercalated ducts extend as in the acini?

centroacinar cells

102

what epithelium is found in the large intercalated ducts of the pancreas?

simple cuboidal

103

what do the intercalated ducts produce?

a bicarbonate rich water secretion that drains into the extensive duct system (to later intercalated ducts then into interlobular ducts)

104

what epithelium is found in the interlobular ducts of the pancreas? where are the interlobular ducts located?

simple columnar epithelium; located in the CT septae

105

what are aciniar cell secretions stimulated by?

Cholecystokinin (CCK): from the enteroendocrine cells
Acetylcholine (ACh) from parasympathetic vagal fibers

106

what are the duct cells of the pancreas stimulated by? what is their function?

stimulated by SECRETIN to increase bicarbonate transport into the ductal lumen

107

what are the islets of Langerhans supplied by?

fenestrated capillaries

108

How do the islets of Langerhans stain (with respect to acini cells)

stain pale (light pink) around darker staining acini

109

What percent of the islets of langerhans are made up of Beta cells?

60-70%

110

where are Beta cells located in the islets of Langerhans?

in the center

111

what inclusion is unique to Beta cells

a crystalloid center that contains insulin

112

What are the steps of insulin PRODCUTION?

1. Preproinsulin is synthesized in the rER
2. The signal peptide is cleaved to form proinsulin (still in the rER)
3. proinsulin is packaged into secretory vesicles in the golgi; in the vesicles a specific protease cleaves the C peptide from the A and B chains (which are held together by disulfide bonds), resulting in the formation of a mature insulin hormone and C peptide

113

what holds the A and B chains together in the formation of insulin?

disulfide bonds

114

What are the steps of insulin secretion?

1. Glucose enters the Beta cell through the insulin independent gluoces transporter protein -2 (GLUT-2)
2. Glucose undergoes glycolysis and the ATP that results inhibits the ATP-sensitive K+ channel
3. This leads to membrane depolarization and opening of the voltage dependent calcium channels
4. Resulting increase in cytoplasmic calcium triggers insulin to be released from the vesicles via exocytosis (MEROCRINE SECRETION)

115

what type of secretion is involved in insulin secretion?

merocrine secretion

116

What is insulins function in the uptake of glucose by muscle and adipose cells?

it translocates a glucose transporter (GLUT-4) from the golgi apparatus to its site of action in the plasma membrane

117

what stimulates glycogen synthesis in the liver hepatocytes?

insulin

118

What is type I diabetes caused by?

destruction of Beta Cells

119

what is type II diabetes caused by?

a deficiency in insulin receptor mechanisms

120

What percent of the islets of langerhans are made up of alpha cells?

15-20%

121

what do alpha cells contain?

larger dense cored granules containing GLUCAGON

122

when is glucagon released? what is the result of its release?

stimulated by LOW blood glucose; stimulates the metabolic breakdown of glycogen in the liver

123

What percent of the islets of langerhans are made up of Delta (D) cells?

5-10%

124

what do Delta cells secrete?

somatostatin and some gastrin

125

what is the function of somatostatin?

inhibits the release of other pancreatic hormones

126

What percent of the islets of langerhans are made up of PP cells (F cells)

3-5%

127

what do PP cells (Fcells) produce? what is its function?

pancreatic polypeptide; it self-reulates pancreatic secretions