Liver anatomy and histology

Question 1

Describe the blood supply to the liver

Answer 1

Double blood supply:
- hepatic artery - 30%, rich in oxygen
- hepatic portal vein - 70%, rich in nutrients, poor in oxygen

Question 2

What is the clinical relevance of the double blood supply to the liver

Answer 2

Liver has limited oxygen supply as most is supplied via hepatic portal vein
Stress can cause liver to become anoxic

Question 3

Describe the regeneration of the liver when cell death is ongoing

Answer 3

Liver is very good at regenerating - not good in this case
Mixture of scar tissue and regenerating cells distorts the architecture
Abnormal architecture damages blood flow and therefore function and more cells die
Creates a cycle of death/scarring/regeneration = Cirrhosis

Question 4

Describe the regeneration of the liver where lobe has been removed

Answer 4

Liver is very good at regenerating so the same original mass will return (will not look the same)

Question 5

Describe the histology of the liver

Answer 5

Hepatic parenchyma - functional part of liver
Principal cell = hepatocyte
Hepatic stroma = structural tissue of liver

Question 6

Describe the histology of the hepatic stroma

Answer 6

Thin fibres of connective tissue (reticulin fibres + collagen type III) forms thin layer => ‘floppy’

Question 7

Label the histology of the liver

Answer 7

Question 8

Describe the anatomy of a classic liver lobule?

Answer 8

hepatocytes are organised in radial cords with portal triads at each corner and a single central vein

Question 9

Label the classic liver lobule

Answer 9

Question 10

Describe the components of the portal tract/triad in classic liver lobules

Answer 10

Branch of hepatic artery
Branch of hepatic portal vein
Bile duct
Surrounded by connective tissue
Large triads also contain lymphatic vessels and autonomic nerves
Limiting plate: discontinuous border of hepatocytes forms outer boundary

Question 11

What is a hepatic sinusoid

Answer 11

fenestrated blood vessels running along the plates of hepatocytes
Portal vein blood and hepatic artery blood mix here

Question 12

What is the function of the central vein in a classic liver lobule?

Answer 12

receive blood from sinusoids and return it to circulation via hepatic vein

Question 13

Label this portal tract/triad

Answer 13

Question 14

Label this liver lobule

Answer 14

Question 15

What are the cell types found in the liver?

Answer 15

Hepatocytes
Endothelial cells
Kupffer cells (sinusoidal macrophages)
Hepatic stellate cells/ Ito cells

Question 16

Label the cells of the liver lobule

Answer 16

Question 17

Label the cells of the liver lobule

Answer 17

Question 18

Describe the morphology and function of kupffer cells

Answer 18

macrophage-like
defend against vascular carrer pathogens and remove debris

Question 18

Describe the morphology and function of hepatocyes

Answer 18

Polyhedral with round nucleus and prominent nucleolus
Metabolise and store materials absorbed from the SI, and secrete bile

Question 19

Describe the morphology and function of Ito cells in the liver

Answer 19

Contain big intracytoplasmatic vacuoles
Involved in tissue fibrosis and in retinol metabolism (Store vitamin A)

Question 20

Label the cells of the liver sinusoids

Answer 20

Question 21

Label the cells of the liver sinusoid

Answer 21

Question 22

Label the cells of the liver sinusoid

Answer 22

Question 23

What is the function of the smooth endoplasmic reticulum in the hepatocyte?

Answer 23

contains main enzymes involved in detoxification (cytochrome P450)
Involved in lipid and glycogen metabolism

Question 24

What is the function of peroxisomes in the hepatocyte?

Answer 24

contains enzymes involved in detoxification e.g., catalase

Question 25

Describe the function of the rough endoplasmic reticulum in the hepatocyte?

Answer 25

binds ribosomes engaged in translating mRNA to proteins involved in protein and lipid modifications

Question 26

What is the function of the golgi apparatus in the hepatocyte?

Answer 26

associated with protein secretion (important for bile secretion) involved in protein and lipid modification

Question 27

Label the organelles of the hepatocyte

Answer 27

Question 28

What is the role of mitochondria in hepatocytes?

Answer 28

aerobic supply of energy - ATP production

Question 29

What is the role of lysosymes in the hepatocytes

Answer 29

digestion of macromolecules

Question 30

What is the role of glycogen in the hepatocytes

Answer 30

Short-term storage of glucose The liver is the main store of glycogen

Question 31

What is the function of lipid droplets in hepatocytes?

Answer 31

storage of esterified fatty acids

Question 32

What organelles can be found in hepatocytes?

Answer 32

Question 33

What is the biliary tree?

Answer 33

Biliary canaliculi (intercellular channels) formed between adjacent hepatocytes form a network => biliary tree Canals of Hering drain into bile ducts of portal tracts

Question 34

What is the function of the gall bladder?

Answer 34

storage, concentration and release of bile - empties via the cystic duct into the duodenum Bile => fat digestion and hepatic excretion

Question 35

Describe the histology of the gall bladder

Answer 35

fibromuscular sac lined with simple columnar epithelium with numerous folds when non-distended No muscularis mucosae or submucosa

Question 36

Label the histology of the gall bladder

Answer 36

Question 37

Describe blood and bile flow in the liver lobule

Answer 37

Bile and blood flows are in opposite directions

Question 38

What is the difference between a classic liver lobule, portal lobule and hepatic acinus?

Answer 38

Portal lobule - triangular area centred on portal tract Classic lobule - area centred on central vein, stresses the exocrine glandular function Hepatic acinus - emphasises vascular supply to hepatic parenchyma and the direction of blood flow

Question 39

Label the different divisions of the hepatic parenchyma

Answer 39

Question 40

Describe the zones of the hepatic acinus

Answer 40

Zone 1 - closest to portal tract receives most oxygenated blood Zone 3 - receives least oxygenated blood as is furthest away from portal tract Zone 3 has a higher detoxification activity (e.g., cytochrome P450)

Question 41

What are the pathological implications within a hepatic acinus

Answer 41

Zone 3 heptatocytes are more susceptible to hypoxic injury and injury by toxic substances that are metabolically activated by cytochrome P450 = centrilobular necrosis Zone 1 hepatocytes are more susceptible to direct-acting toxicants = perilobular necrosis