Liver structure and function

Question 1

What is secretin?

Answer 1

A hormone released into the bloodstream by the duodenum (especially in response to acidity) to stimulate secretion by the liver and pancreas

Question 2

What is the largest organ in the body?

Answer 2

Liver

• Weighs 1.4kg

Question 3

What are the 2 major and minor lobes of the liver?

Answer 3

2 major lobes: Right > Left

2 minor lobes: Caudate, Quadrate

Question 4

What is the porta hepatis?

Answer 4

The fissure running transversely on the underside of the liver where most of the vessels enter or leave

Question 5

What structures enter or leave the liver at the porta hepatis?

Answer 5

The portal vein, the hepatic artery, and the common hepatic duct

Question 6

What is the common hepatic duct joined by?

Answer 6

Common hepatic duct joined by cystic duct from gallbladder > common bile duct + pancreatic duct > major duodenal papilla (Sphincter of Oddi)

Question 7

Whats the ligament that passes down between the right and left lobe of the liver?

Answer 7

Falsiform ligament

Question 8

What ligament from the liver attaches to the underside of the diaphragm?

Answer 8

Coronary ligament

Question 9

What is the liver covered by?

Answer 9

Liver covered by connective tissue capsule and visceral peritoneum except for bare area (small area on diaphragmatic surface surrounded by coronary ligament)

Question 10

What does the septa divide into?

Answer 10

Septa divides into hexagonal lobules

Question 11

What is the portal triad composed of?

Answer 11

Hepatic portal vein

Hepatic artery

Hepatic duct

Question 12

Where is the portal triad located?

Answer 12

At each corner of hexagonal lobule (also nerves and lymph vessels)

Question 13

Where do the central veins go?

Answer 13

Central veins at the centre of the hexagon form hepatic veins then these drain into the inferior vena cava

Question 14

Where do hepatic cords radiate to?

Answer 14

They radiate out from central veins (like spokes of wheels)

• Hepatic cords are composed of hepatocytes

Question 15

What is the bile canaliculus?

Answer 15

Bile canaliculus is a thin tube that collects bile secreted by hepatocytes.

• The bile canaliculi empty into a series of progressively larger bile ductules and ducts, which eventually become common hepatic duct.

Question 16

What are the spaces between hepatic cords called?

Answer 16

Hepatic sinusoids (blood channels)

Question 17

What are sinusoids?

Answer 17

They are low pressure vascular channels that receive blood from terminal branches of the hepatic artery and portal vein and deliver it to central veins

Question 18

What is the movement of blood and bile from the liver lobule?

Answer 18

Blood travels from the portal triad inside to the central vein outside

Bile travels from the central vein inside to the bile canaliculus outside

Question 19

What is the sequence of the hepatic portal vein artery drainage?

Answer 19

Hepatic artery/ portal vein > Hepatic sinusoids > central veins > hepatic veins > inferior vena cava

Question 20

What are the functions of hepatocytes?

Answer 20

Bile synthesis

Nutrient storage: glycogen fat, vitamins (B12, A, D, E, K), Cu, Fe), nutrient interconversion, detoxification

Question 21

What is the main alimentary role of liver?

Answer 21

Production & secretion of bile

Question 22

What are the six components of bile?

Answer 22

Bile acids

Lecithin

Cholesterol

Bile pigments - bilirubin (from haemoglobulin)

Toxic metals - detoxified in liver

Bicarbonate - neutralisation of acid chyme

Question 23

Which components of bile are synthesised in liver and soluble in fat?

Answer 23

Bile acids

Lecithin

Cholesterol

Question 24

What is HCO3 secreted by?

Answer 24

Duct cells

Question 25

What are bile pigments?

Answer 25

Breakdown products of haemoglobin from old/damaged erythrocytes

Question 26

What is the predominant bile pigment?

Answer 26

Bilirubin

• Extracted from blood by hepatocytes and secreted into bile

Question 27

Where and how are bile acids synthesised?

Answer 27

Synthesised in live from cholesterol (0.5g/day)

• Before secretion, bile acids conjugated with glycine or taurine > bile salts (increased solubility)

Question 28

How are bile salts recycled?

Answer 28

Secreted bile salts recycled via enterohepatic circulation

Liver > bile duct > duodenum > ileum > hepatic portal vein > liver

Question 29

What is the Gallbladder?

Answer 29

Saclike structure on inferior surface of liver

Primary function is to store and concentrate bile

Question 30

What are the three layers in wall of gallbladder?

Answer 30

Mucosa (folded > rugae > expansion)

Muscularis (smooth muscle) > contraction

Serosa (connective tissue)

Question 31

What is the function of Sphincter of Oddi?

Answer 31

Controls release of bile and pancreatic juice into duodenum

When contracted (closed) > bile forced back into gallbladder

Question 32

How much does the gallbladder concentrate bile?

Answer 32

Concentrates 5-20 times (absorbs Na+ & H2O)

Question 33

What 2 things do you need together to digest fat?

Answer 33

Bile and Lipase

Question 34

What does fat in the duodenum cause the release of?

Answer 34

Release of CCK

CCK causes:

a) Sphincter of Oddi relaxes
b) Gallbladder contracts

Question 35

What does discharge of bile into duodenum cause?

Answer 35

Fat solubilisation

CCK causes:
pancreatic enzyme secretion and bile secretion