GI HISTOLOGY - A17 GI Lecture V- Liver and biliary system

Question 1

Main functions of the liver and biliary system:

Answer 1

Produces plasma proteins.Stores vitamins and iron.Degrades drugs and toxins.Produces bile.

Question 2

Structure of liver parenchyma:

Answer 2

Organized plates of hepatocytes.Separated by sinusoidal capillaries.Contains CT stroma.

Question 3

Structure of the classic liver lobule:

Answer 3

Hexagonal mass with a central vein.Portal triads at hexagon angles.Measures about 2.0 X 0.7 mm.

Question 4

Characteristics of hepatocytes:

Answer 4

Large, polygonal cells (20-30 µm).80% of liver cell population.Large nuclei and eosinophilic cytoplasm.

Question 5

Significance of the portal triad:

Answer 5

Branches of portal vein and hepatic artery.Draining branches of bile duct system.

Question 6

Lifespan and regeneration of hepatocytes:

Answer 6

Lifespan: ~5 months.Capable of significant regeneration.

Question 7

Role of liver in vitamin metabolism:

Answer 7

Maintains vitamin A levels.Converts vitamin D3 to active form.

Question 8

Components of liver’s connective tissue stroma:

Answer 8

Continuous with Glisson’s capsule.Contains blood vessels and nerves.

Question 9

Arrangement of hepatocyte plates:

Answer 9

Stacked in anastomosing patterns.Radiate from central vein.

Question 10

Appearance of hepatocytes under H&E:

Answer 10

Foamy appearance due to glycogen.Lipid droplets visible.

Question 11

Main components of liver blood supply:

Answer 11

Portal vein: 75-80% of blood.Hepatic artery: 20-25% of oxygenated blood.

Question 12

Role of hepatic sinusoids:

Answer 12

Mix venous and arterial blood.Facilitate nutrient and waste exchange.

Question 13

Cells in hepatic sinusoids:

Answer 13

Endothelial cells.Kupffer cells (macrophages).

Question 14

Function of the Space of Disse:

Answer 14

Separates hepatocytes from blood.Facilitates protein absorption.

Question 15

Significance of hepatic stellate cells:

Answer 15

Store vitamin A.Produce extracellular matrix components.

Question 16

Bile synthesis and secretion:

Answer 16

Synthesized by hepatocytes.Secreted into canaliculi.

Question 17

Direction of bile flow:

Answer 17

Centrifugal: from central vein to portal canal.Opposite to blood flow.

Question 18

Structure and function of the limiting plate:

Answer 18

Row of hepatocytes bordering portal tracts.Organizes liver structure.

Question 19

Components of bile flow regulation:

Answer 19

Hormonal control (e.g., CCK).Neural control influences secretion.

Question 20

Structure of bile canaliculi and canals of Hering:

Answer 20

Transform into canals of Hering.Facilitate bile drainage.

Question 21

Biliary tract and bile flow:

Answer 21

Channels of increasing diameter.Cholangiocytes enhance absorption.

Question 22

Role of lymphatic pathway in liver:

Answer 22

Drains plasma into lymphatic capillaries.Aids fluid balance and immune function.

Question 23

Significance of reticulin fibers:

Answer 23

Maintain liver structural integrity.Support hepatocytes.

Question 24

Describing liver structure:

Answer 24

Liver lobules (classic, portal, acinus).Functional units of liver.

Question 25

Defining the portal lobule:

Answer 25

Lozenge-shaped, smallest functional unit.Defined by central veins.

Question 26

Structure and function of liver acinus:

Answer 26

Defined by portal triad and central veins.Arranged in concentric zones.

Question 27

Arrangement of hepatocytes in acinus:

Answer 27

Three concentric zones.Facilitates bile secretion.

Question 28

Characteristics of Zone 1:

Answer 28

Closest to short axis.Receives blood from portal vein and hepatic artery.

Question 29

Defining Zone 3:

Answer 29

Farthest from short axis.Closest to central vein.

Question 30

Significance of Zone 2:

Answer 30

Transitional area between Zones 1 and 3.

Question 31

Liver acinus relevance:

Answer 31

Functional unit reflecting structure-function relationship.

Question 32

Structure and function of liver capsule:

Answer 32

Dense connective tissue capsule (Glisson’s).Provides support and shape.

Question 33

Role of gallbladder in digestion:

Answer 33

Stores and concentrates bile.Removes water from bile.

Question 34

Gallbladder response to fat:

Answer 34

Hormones stimulate contractions.Releases bile into digestive tract.

Question 35

Structural composition of gallbladder:

Answer 35

Mucosa with simple columnar epithelium.Muscularis with varied muscle fiber orientation.

Question 36

Rokitansky-Aschoff sinuses:

Answer 36

Deep mucosal diverticula.Indicate pathologic changes.

Question 37

Innervation of liver and gallbladder:

Answer 37

Nerves from sympathetic and parasympathetic systems.Enter at porta hepatis.

Question 38

Effects of sympathetic fibers:

Answer 38

Increase vascular resistance.Raise serum glucose levels.

Question 39

Role of parasympathetic fibers:

Answer 39

Innervate ducts and blood vessels.Promote glucose uptake.

Question 40

Liver cirrhosis impact:

Answer 40

Connective tissue fills perisinusoidal space.Interferes with metabolic exchange.

Question 41

Common causes of liver diseases:

Answer 41

Alcoholic liver disease.Non-alcoholic steatohepatitis (NASH).Chronic hepatitis B and C.

Question 42

Factors contributing to gallstone formation:

Answer 42

Obesity increases risk.Increased cholesterol and biliary excretion.

Question 43

Main structures in liver anatomy:

Answer 43

Liver lobules.Sinusoids and hepatocytes.Biliary tract.

Question 44

Layers of the gallbladder:

Answer 44

Distinct layers contribute to function.

Question 45

Diseases associated with liver and gallbladder:

Answer 45

Alcoholic liver disease and hepatitis.Gallstones.