Histology of Liver, Exocrine Pancreas and Gall Bladder

Question 1

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Answer 1

Question 2

The ____________ serves as the point of entry into the liver for the hepatic arteries and the portal vein, and the exit point for the hepatic ducts.

Answer 2

porta hepatis

Question 3

The whole surface of the liver except for the _________, is covered in a serous coat derived from the peritoneum, and this firmly adheres to the inner Glisson’s capsule.

Answer 3

bare area

Question 4

Glisson’s capsule

Answer 4

A layer of connective tissue surrounding the liver and ensheathing the hepatic artery, portal vein and bile ducts within the liver.

Question 5

At rest the liver normally receives about _______ of cardiac output.

Answer 5

25%

NOTE: The liver is unique amoung abdominal organs in having a dual blood supply, from the hepatic arteries and hepatic veins.

Question 6

What are the two blood supplies of the liver?

Answer 6

• Portal artery
  
  • 20-30%
  • Supplies oxygen rich blood
• Portal vein
  
  • 70-80%
  • Supplies nutrient rich blood from the digestive tract

NOTE: The portal blood also contains breakdown products of hemoglobin from the spleen.

Question 7

Where does blood from the head of the pancreas drain?

Answer 7

Superior mesenteric vein

NOTE: The tail of the pancreas drains into the splenic vein

Question 8

What are the components of the portal triad?

Answer 8

• Branches of the hepatic artery and vein
• One or two bile ductules
• Lymphatic vessels
• Branch of vagus nerve

Question 9

Explain the blood flow from the portal triads to the inferior vena cava.

Answer 9

Portal triads->central vein->sublobar vein->collecting vein->hepatic veins-> inferior vena cava

Question 10

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Answer 10

Question 11

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Answer 11

Question 12

What are the 3 functional units of the liver? What’s the function of each?

Answer 12

• Classic Hepatic Lobule
  
  • ​Drains blood from the portal vein and the hepatic artery to the hepatic or the central vein
• Portal Lobule
  
  • ​Drains bile from hepatocytes to the bile duct
• Hepatic Acinus
  
  • ​Supplies oxygenated blood to hepatocytes

NOTE: The hepatic acinus is the most funtional way to conceptualize the liver lobule based on blood flow.

Question 13

What are the 3 metabolic zones of the hepatic acinus?

Answer 13

Zone I

• Least oxygenated

Zone II

Zone III

• Most oxygenated

Question 14

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Answer 14

Question 15

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Answer 15

Question 16

Central veins coalesce into __________.

Answer 16

Hepatic veins

*Which leave the liver and empty into the vena cava

Question 17

Purpose of the liver sinusoid

Answer 17

A liver sinusoid is a type of a capillary similar to a fenestrated capillary and serves as a location for mixing of oxygen rich blood from the hepatic artery and the nutrient rich blood from the portal vein

Question 18

How does the liver sinusoids differ from other capillaries?

Answer 18

• Larger
• Lining of specialized endothelial cells, known as liver sinusoidal cells (LSEC)

Question 19

Basolateral surface of the hepatocyte faces ______, and apical surfaces face ___________.

Answer 19

Sinusoids; bile canaliculi

Question 20

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Answer 20

Question 21

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Answer 21

Question 22

Characteristics of the nucleus of hepatocytes

Answer 22

• Prominent nucleolus
• Dispersed chromatin
• Polyploidy

Question 23

Characteristics of the cytoplasm of hepatocytes

Answer 23

• Glycogen lacey appearance
• Fat spherical vacuoles
• Ribosomes and RER basophilia
• Mitochondira- eosinophilic
• Lysosomes
• Golgi complex
• Peroxisomes

Question 24

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Answer 24

Question 25

Most of the glucose absorbed from a meal is stored as _________ in the liver.

Answer 25

Glycogen (5-6% of the liver's fresh weight) **NOTE:** Glucose is also stored in muscles

Question 26

Blood glucose enters hepatocytes via which transporter?

Answer 26

GLUT2

Question 27

The human body can store up to _____ grams of glycogen.

Answer 27

450 \*A third of this is stored in the liver

Question 28

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Answer 28

Glycogen

Question 29

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Answer 29

Question 30

Which structure of hepatocytes function to synthesize and secrete plasma proteins?

Answer 30

RER ## Footnote **Ex:** Albumin, fibrinogen, thrombin

Question 31

Which structure of hepatocytes function to synthesize and secrete bile?

Answer 31

**SER** * Bile acids from cholesterol * Elimination of bilirubin * Secretion of secretory IgA

Question 32

Which structure of hepatocytes function to metabolize carbohydrates?

Answer 32

SER, cytosol

Question 33

Which structure of hepatocytes function to metabolize lipids?

Answer 33

RER

Question 34

Which structure of hepatocytes function to maintain normal levels of blood lipids?

Answer 34

VLDL

Question 35

Function of the smooth endoplasmic reticulum

Answer 35

* Synthesis lipids, oils, phospholipids, steroids, and sex hormones * Hydrolysis of glycogen into glucose * Detoxification of drugs and poisons * Pumps calcium ions for muscle function

Question 36

\_\_\_\_\_\_\_\_\_\_\_ are spaces present between the plasma membrane of adjacent liver cells.

Answer 36

Bile canaliculi

Question 37

Flow of bile

Answer 37

Bile canaliculi-\> Canals of Hering-\> intrahepatic bile ductule (in portal triad)-\>Interlobular bile ducts-\> left and right hepatic ducts-\> Common hepatic duct **NOTE:** The common hepatic duct joins with the cystic duct which becomes the **bile duct**, which enters the _duodenum_

Question 38

Function of Kupffer cells

Answer 38

Continuously sample the blood travelling through the sinusoids, phagocytosing antigens, microorganisms and damaged red blood cells.

Question 39

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Answer 39

Question 40

Which component of hepatocytes is being described below? * **A subendothelial space** * **Space between hepatocytes and sinusoidal lining cells** * **Microvilli of hepatocytes project into the space** * **Fat storing stellate cells that store Vitamin A found here** * **Space continuous with sinusoids** * **Space drains to lymphatics of portal triad**

Answer 40

Space of Disse

Question 41

Which component of hepatocytes is being described below? * **Lie in perisinusoidal space** * **Have long cytoplasmic processes that extend below the endothelial cells** * **Contain actin and myosin and contract in response to endothelin and substance P** * **Contribute to regulate the diameter of the sinusoid** * **Store fat and Vitamin A**

Answer 41

Ito (stellate cells)

Question 42

Ito cells can proliferate when activated by _____ and \_\_\_\_\_\_\_\_.

Answer 42

Kupffer cells; hepatocytes

Question 43

What happens to Ito cells in pathological conditions?

Answer 43

* They change into _collagen producing_ cells * They secrete **type I collagen** leading to _fibrosis_ of the liver * As the fibrotic process advances, ito cells change into myofibroblasts which contrict the lumen of the sinusoids and increase vascular resistance * An increase in resistance to the flow of blood in the hepatic sinusoids leads to portal **hypertension**

Question 44

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Question 45

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Question 46

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Answer 46

Question 47

Which portion of the pancrease makes and secretes digestive enzymes into the duodenum?

Answer 47

Exocrine ## Footnote **NOTE:** This includes secretory acinar and duct cells with associated connective tissue, vessels, and nerves.

Question 48

Components of exocrine pancreas

Answer 48

**NOTE:** Most pancreatic enzymes are produced as _zymogens_, which help minimize the risk of self digestion within the pancreas

Question 49

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Answer 49

Question 50

What are the two portions of the cytoplasm of each acinar cell?

Answer 50

* **Apical** * **​**Filled with **eosinophilic protein secretory granules** * **Basal** * **​**Strongly **basophilic** * Replet with RER

Question 51

What accounts for the dark appearance of secretory ganules?

Answer 51

High concentration of proteins (enzymes) and other macromolecules **NOTE:** Secretory granules are primarily found in the apical side of the cell. Fusion with the plasma membrane releases the contents of the granules into the extracellular space.

Question 52

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Answer 52

Question 53

What are the two secretory products of pancreatic juice?

Answer 53

* Digestive enzymes * Synthesized and secreted from the **exocrine acinar cells** * Bicarbonate * Secreted from the **epithelial cells lining small pancreatic ducts**

Question 54

When is secretin secreted?

Answer 54

In response to acid in the **duodenum** which stimulates duct cells to produce _water and bicarbonate_

Question 55

How is merocine secretion of proenzymes by acinar cells regulated?

Answer 55

* Secretin * Cholecystokinin * Nerve stimulation from the vagus nerve

Question 56

Components of acinar cells of the pancreas

Answer 56

* Trypsin * Chymotrypsin * Elastase * Sodium bicarbonate

Question 57

How is trypsinogen activated?

Answer 57

* By enterokinase, which is embedded in the mucus membrane of the duodenal mucosa **NOTE:** Trypsin is autocatalytic which means that trypsin, once activated, forms more trypsinogen, which is then activated to trypsin

Question 58

Chymotrypsinogen and procarboxypeptidase are converted to an active form by ______ in the duodenal lumen.

Answer 58

Trypsin

Question 59

Bile empties to the common bile duct under ________ stimulation.

Answer 59

Hormonal **NOTE:** **Cholecystokinin** stimulates the gallbladder. Cholecystokinin (CKK) is secreted by the I cells of the intestinal mucosa.

Question 60

Once stimulated by CCK, how does the gallbladder respond?

Answer 60

By contracting and delivering more bile to the duodenum through the _Sphincter of Oddi**,**_ which relaxes (opens) in response to CCK.

Question 61

Function of bile

Answer 61

* Excretion of cholesterol, phospholipids, bile salts, conjugated bilirubin and electrolytes * Contributes to fat absorption in the intestinal lumen * **Transports IgA** to the intestinal mucosa by enterohepatic circulation * **Excretion of metabolic products of drugs and heavy metals** processed in the hepatocyte * Conjugated bile acids **inhibit the growth of bacteria** in the small intestine

Question 62

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Answer 62

Question 63

What are the 4 layers of the gall bladder?

Answer 63

* Lining epithelium (simple columnar) * Lamina propria * Rich in elastic fibers and blood vessels * Muscularis * Consists of circularly arranged smooth muscle fibers intermixed with connective tissue rich in elastic fibers * Serosa/ adventitia

Question 64

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Answer 64

Question 65

Cholecystitis

Answer 65

* Inflammation of the gall bladder * Rokitansky-Aschoff sinuses- herniation of mucosa into muscular wall