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SF3_3 (Kereen) > Histology of Liver, Gallbladder, and Pancreas > Flashcards

Histology of Liver, Gallbladder, and Pancreas Flashcards

1
Q

What are the ligaments of the liver?

A

Falciform ligament

Triangular ligaments

Coronary ligaments

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2
Q

What is Glisson’s capsule?

A

A layer of connective tissue surrounding the liver

Ensheaths the hepatic artery, portal vein, and bile ducts within the liver

also called the hepatobiliary capsule

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3
Q

How much of the cardiac output does the liver recieve at rest?

A

25%

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4
Q

What sets the liver apart from the other abdominal organs?

A

Recieves dual blood supply

  1. hepatic arteries = oxygen rich blood (20-30%)
  2. hepatic protal veins - nutrient rich blood from digestive tract (70-80%), break down of hemoglobin from the spleen
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5
Q

What is the central role of the liver?

A

removing unwanted material from blood and otherwise maintaining the bloods normal composition

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6
Q

Lobule Architecture of liver

A

Central vein

peripheral portal triad

Roughly heaxagonal

connective tissue septum

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7
Q

What does the portal triad in the lobule contain?

A

branches of hepatic artery, vein, one or two bile ductules, lymphatic vessels and branches of the vagus nerve

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8
Q

What is the blood flow in the liver?

A

portal triad -> central vein (terminal hepatic venule) -> sublobular vein -> collecting vein -> hepatic veins -> inferior vena cava

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9
Q

describe the sinusoids of the liver?

A

Fenestrated lining (endothelial cells)

Hepatic macrophages in sinusoid walls

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10
Q

Bile ducts in the lobule recieve bile from where?

A

canaliculi

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11
Q

classic hepatic lobule drains blood from where?

A

from the portal vein and the hepatic artery to the hepatic or the central vein

(drains inward)

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12
Q

portal lobule drains bile from?

A

hepatocytes to the bile duct

(drains outward)

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13
Q

How do hepatocytes recieve oxygenated blood?

A

From hepatic acinus

flows inward

Zone 3 (centrilol) is least oxygenated

Zone 2 (Midzonal)

Zone 1 (periportal) is the most oxygenated

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14
Q

Acinus of Rappaport

A

these are the hepatic acinus

encompases an oval to diamond shaped region from two or three classical lobules and is divided into three zones in the parenchyma

Most functional way (both physiological and biochemically) to conceptualize the liver lobule based on blood flow

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15
Q

Liver Sinusoidal Endothelial Cells (LSEC)

A

thin lining of specialized endothelial cells
large and Fenestrated

Mixed blood from oxygen rich hepatic artery and nutrient rich blood from portal vein.

Blood flow = through sinusoids -> central vein of lobule -> central vein coalesce into hepatic veints -> vena cava

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16
Q

What is the relationship between sinusoids and hepatocytes?

A

Blood in sinusoids bathes hepatocytes and provide for exchange of substances betwen blood and liver cells

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17
Q

Basolateral surface of hepatocyte faces _______ sinusoids, apical surfce face ______ ______.

A

sinusoids

bile canaliculi

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18
Q

When blood passes freely through fenestration of sinusoids where does it go?

A

Into perisinusoidal space (Space of Disse)

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19
Q

What are hepatocytes?

A

Liver cells that are cuboidal

Polarized

arranged in a flat, irregular plates (cords) that are organized radially, like the spokes of a wheel.

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20
Q

What is the content of a hepatic plate?

A

Contains one or two rows of hepatocytes and these lie in between the sinusoids

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21
Q

The nucleus of the hepatocyte is?

A

Has a prominent nucleolus

Dispersed chromatin

Polyploidy

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22
Q

Describe the cytoplasm of the hepatocyte?

A

Glycogen lacey appearance

fat sphreical vacuoles

Riosomes and RER basophilia

Mitochondria - eosinphilic

Lysosomes

Golgi complex

Peroxisomes

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23
Q

Most of the glucose absobed from a meal is stored where?

A

In the liver as glycogen ( also in muscles)

In the liver glycogen makes up 5-6% of the organs fresh weight and an adult can store about 100-120 grams of glycogen

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24
Q

About how much glucose is present in the blood at all times?

A

4 grams

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25
Q

What allows glucose to enter the hepatocytes?

A

GLUT2

a plasma membrane glucose transporter

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26
Q

Storage of Glycogen

A

the human body can store up to 450 g of glycogen (1/3 of this in the liver)

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27
Q

What is the purpose of liver glycogen?

A

Serves as a maintenance of the blood glucose level

it declines to zero in periods of fasting that last more than one day.

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28
Q

What are the different processes that occur in the liver?

A
  • Synthesis and secretion of plasma proteins (RER) - albumin, fibrinogen, and thrombin
  • Synthesis and secretion of bile (SER) - bile acids from cholesterol, elimination of bilirubin, secretion of secretory IgA
  • Metabolism of carbohydrates (SER, cytosol)
  • Maintenance of normal level of blood glucose
  • Metabolism of lipids (RER)
  • Maintenance of normal level of blood lipids - VLDL
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29
Q

What is the function of the smooth endoplasmic reticulum?

A

Function - metabolic processes - synthesis nad hydrolysis

Enzymes - synthesis of lipids, oils, phospholipids, steroids, and sex hormones

Hydrolysis of glycogen into glucose (in liver)

Detoxification of drugs and poisons (in liver)

Pumps calcium uons for muscle funciton

30
Q

What are bile canaliculi?

A

spaces present between plasma membran of adjacent liver cells

31
Q

Describe the flow of bile

A

Bile canaliculi > canals of Hering > intrahepatic bile ductule (inportal triad) > interlobular ducts > left and right hepatic ducts > common hepatic duct joins with cystic duct > bile duct > duodenum

32
Q

What cell lines the sinusoids and is considered a type of fixed macrophage?

A

Kupffer Cells

33
Q

What is the function of Kupffer cells?

A

They continuosly sample the blood traveling through the sinusoid, phagocytosing antigens, microorganism and damaged RBC.

34
Q

Identifying Kupffer cells in conventionally stained sections is not easy. When are they identifable and stand out?

A

When they are full of phagocytosed ink particles

35
Q

What is Space of Disse?

A

Perisinusoidal space/Subendothelia

between heptacytes and sinusoidal lining cells

microvilli of hepatocytes project into space

space continuous with sinusoids

36
Q

The space of Disse drains into?

A

lymphatics of portal triad

37
Q

What cells are found in the Space of Disse?

A

Fat storing (Ito, stellate) cells

They also store vitamin A

38
Q

Reticular connective tissue

A

Type II collagen = reticular fibers

lots of proteoglycan (flexibility)

form a delicate network within the space of Disse

seen with silver stain

39
Q

Ito (stellate cells)

A

Located in the perisinusoidal space

long cytoplasmic processes that extend below the endothelial cells

contain actin and myosin

store fat and vitamin A

40
Q

The Ito cells contract in response to what?

A

In response to endothelian and substance P

this contributes to regulation of the diameter of the sinusoid and hence regulates blood flow

41
Q

When do Ito cells proliferate?

A

When activated by Kupffer cells and hepatocytes

42
Q

In pathologial conditions Ito cells change into?

A

Collagen producing cells

Secrete Type I collagen leading to progrssive fibrosis of the liver

43
Q

When do Ito cells change into myofibroblast?

A

Progressive fibrosis of the liver is occuring and as it advance the Ito cells turn into myofibroblast.

This constrict the lumen of the sinusoid and increase vascular resistance

Increase in resistance to blood flow in the hepatic sinusoids = portal hypertension

44
Q

What are the changes that occur during liver injury?

A

Activated stellate cells

deposition of scar matrix

Kupffer cell activation

Loss of fenestration

Loss of hepatocyte microvilli

45
Q

What are the histological changes with Cirrhosis?

A

Fibrous Septa

Regenerative nodules

Fatty Cyst

Nerosis

46
Q

What makes up the endocrine pancreas and the exocrine pancreas?

A

Endocrine - Islet of Langerhans

Exocrine- Acini

47
Q

The pancreas is seperated into lobules by connective tissue. What is in that connective tissue?

A

Blood vessels

nerves

48
Q

The lobule is the what of the pancrease?

A

Secretory Unit

49
Q

Exocrine Pancreas

A

The portion that makes and secretes digestive enzymes into the duodenum.

Includes:

Acinar and duct cells with associated connective tissue, vessles, and nerves

makes up 95% of the pancreatic mass

50
Q

The acini in the exocrine pancreas contain what?

A

Each acini consist of a single layer of epithelial cells surrounding a cavity where the secretory granules (zymogen granules) within the acinar cells delivers secretions to the lumen of the acinus.

51
Q

Acinar cells

A

Pyramidal shaped, round nucleus at the base of cell

basal cytoplasm is basophilic due to abundance of RER

basal membrane receptors for Cholecystokinin from duodenum

Apex contains secretory granules (zymogen) - eosinophilic

release granules of digestive enzymes

52
Q

What do the zymogen granules contain?

A

digestive enzymes and proenzymes

trypsinogen, chymotrysinogen, carboxypeptidase, amylase, lipase, nuclease

53
Q

Human Acinar cells

A

most pancreatic enzymes are produced as inactive molecules = symogens

this helps minimize the risk of self digestion within the pancreas

54
Q

Pancreatic juice is composed of two secretory products critical to proper digestion. What are they?

A

digestive enzymes (synthesized and secreted from the exocrine acinar cells)

bicarbonate (secreted from the epithelial cells lining small pancreatic ducts)

55
Q

When is Secretin secreted?

A

In response to acid in the duodenum, which stimulates duct cells to produce water and bicarb

56
Q

Merocrine secretion of proenzymes by the acinar cells is regulated by?

A

Secretin and Cholecystokinin from the enteroendocrine cells of the duodenum and jejunum with nerve stimulation from the vagus

57
Q

Stomach cells secrete which two things?

A

Pepsin and HCL

58
Q

Pancreatic acinar cells secrete what?

A

Trypsin

Chymotrypsin

Elastase

Sodium Bicarbonate

59
Q

Intestinal Cells secrete what?

A

Secretin

Cholecystokinin (CCK)

60
Q

In the small intestine (duodenum) the epithelial cells contain membrane bound enteropeptidase (enterokinase). What does this do?

A

Convert Trypsinogen -> Trypsin (has a negative feedback mechanism)

Trypsin then activates more tyrpsinogen,

converts Chymotrypsinogen -> Chymotrypsin

and

Procarboxypeptidase -> Carboxypeptidase

61
Q

What is the Gallbladder?

A

A sac for bile storage

80-90% of electrolytes are absorbed in the gallbladder leaving bile acids and cholesterol

62
Q

Bile from the gallbladder empties where?

A

Empties into the common bile duct under hormonal stimulation (cholecystokinin)

63
Q

how is the cystic duct different from other duct?

A

It contains spiral valves

64
Q

Describe the direction of duct drainaige between the lier, gallbladder, and the pancrease

A
  1. The left and right hepatic ducts merge to form a common hepatic duct.
  2. Common hepatic and cystic ducts merge to form a common bile duct
  3. Main pancreatic duct merges with common bile duct at the hepatopancreatic ampulla, which extends into the duodenum
  4. Bile and pancreatic juices enter duodenum at the major duodenal papilla
65
Q

Cholecystokinin (CCK) stimulates the gallbladder. How does the gallbladder respond?

A

Responds by contracting and delivering more bile to the duodenum through the sphincter of Oddi, which relaxes in response to CCK

66
Q

CCK is secreted by?

A

Intestinal mucosa

(I cells)

67
Q

Increase in Fatty acids in the Duodenum leads to what?

A

Increase in CCK sectrion

this leads to a increase in plasma CCK

increase in plasma CCK causes contraction of the Gallbladder and relaxation of the sphinter of Oddi

=

increase in bile flow into common bile duct and increase in bile flow into duodenum

68
Q

What is bile?

A

the excretion of cholesterol, phospholipids, bile salts, conjugated bilirubin and electrolytes

69
Q

What is the function of bile?

A

Contributes to fat absoprtion in the intestinal lumen

Transports IgA to the intestinal mucosa by the enterohepatic circulation

Exretion of metabolic products of drugs and heavy metals processed in hepatocytes

70
Q

Conjugated bile acids inhibit what?

A

The growth of bacteria in the small intestine

71
Q

The Gall bladder has 4 layers. What are they?

A

Lining epithelium - simple columnar

Presense of Microvilli give brush border appwarance to epithelium (facilitates absorption of water

Lamina propria - rich in elastic fibers and blood vessels

Muscularis - consist of circularly arranged smooth muscle fibers mixed with connective tissue rich in elastic fiber

Serosa/Adventitia

72
Q

What are Rokitansky-Aschoff sinuses?

A

herniation of mucosa into muscular wall of the Gallbladder

Seen in Chronic cholecystitis

SF3_3 (Kereen) (14 decks)

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