Liver Structure and Function Flashcards
How much does the liver weigh?
1.4 kg
Where is the liver located?
In the upper right quadrant of the abdomen tucked against the inferior surface of the diaphragm
What are the 2 major lobes of the liver?
Right and left
What are the 2 minor lobes of the liver?
Caudate and quadrate
Entry/ exit of blood vessels, lymphatic vessel, ducts and nerves is via what?
Porta on inferior surface
What blood vessels enter/exit the liver?
- Hepatic portal vein
- Hepatic artery
What ducts enter/exit the liver?
- Right hepatic duct
- Left hepatic duct
- Common hepatic duct
What nerves enter/exit the liver?
Hepatic nerve plexus
Describe the formation of ducts between the liver, gallbladder and pancreas.
- Right and left hepatic ducts join to form common hepatic duct
- Common hepatic duct joins with cystic duct to form common bile duct
- Common bile duct joins with main pancreatic duct and enters duodenum at the major duodenal papilla
What is the liver covered by?
-Connective tissue capsule and visceral peritoneum except for bare area
What is the bare area of the liver?
Small area on diaphragmatic surface surrounded by coronary ligament
What happens to the connective tissue capsule at the porta?
Leads to branching network of septa for support
What doe the vessels, ducts and nerves follow through the liver?
Septa
How does the septa divide the liver?
Into hexagonal lobules
What are the 3 components of the hepatic triad?
- Hepatic portal vein
- Hepatic artery
- Hepatic duct
Where is the portal triad located?
At each corner of hexagonal lobule
What are the central veins at the centre of each lobule?
Hepatic veins which drain into the IVC
How are hepatic cords arranged?
Radiate out from central veins
What are hepatic cords composed of?
Hepatocytes
What are hepatocytes?
Functional cells of the liver
What lies between the cells within each cord?
Bile canaliculus (cleft like lumen)
What are the spaces between hepatic cords?
Hepatic sinusoids (blood channels)
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What is the alimentary role of the liver?
Production and secretion of bile
What are the 6 components of bile?
- Bile acids
- Lecithin
- Cholesterol
- Bile pigments
- Toxic metals
- Bicarbonate
Where are bile salts, lecithin and cholesterol synthesised?
Liver
What do bile salts, lecithin and cholesterol do?
Solubilise fats
What happens to toxic metals in the liver?
Detoxified
What is the function of bicarbonate?
Neutralisation of acid chyme
What secretes bicarbonate?
Duct cells
What secretes bile acids, lecithin, cholesterol bile pigments and toxic metals?
Hepatocytes
What are bile pigments?
Breakdown products of haemoglobin from old/damaged erythrocytes
What produced yellow bile?
Bilrubin extracted from blood by hepatocytes and secreted into bile
What produces brown faeces?
Bilrubin modified by bacterial enzymes leads to brown pigments
What produces yellow urine?
Reabsorbed bilirubin excreted in urine
How are bile acids produced?
Synthesised in liver from cholesterol
What happens before bile acids are secreted?
Bile acids conjugated with glycine or taurine to form bile salts to increase solubility
How are secreted bile salts recycled?
Via enterohepatic circulation
Describe the movement of bile salts.
- Liver
- Bile duct
- Duodenum
- Ileum
- Hepatic portal vein
- Liver
What is the gallbladder?
Saclike structure on inferior surface of liver
What are the 3 layers in the wall of the gallbladder?
- Mucosa
- Muscularis
- Serosa
What is the function of the mucosa?
It is folded in rugae for expansion
What is the function of the muscularis?
Smooth muscle for contraction
What is the serosa?
Connective tissue
What are the relations of the gallbladder?
- Gallbladder
- Cystic duct
- Common bile duct
What does the sphincter of Oddi control?
Controls release of bile and pancreatic juice into duodenum
What happens when the sphincter of Oddi is contracted?
Bile is forced back into the gallbladder
What does the gallbladder do to bile?
Concentrates bile 5-20 times (absorbs Na and H2O)
What does fat in the duodenum result in?
Release of CCK
What does the release of CCK result in?
- Sphincter of Oddi relaxes
- Gallbladder contracts
What does discharge of bile into the duodenum?
Fat solubilisation
Summary of secretin action.
- Acid in duodenum
- Release of secretin
- Decrease in gastric acid secretion
- Decrease in gastric emptying
- Increase duodenal bicarbonate secretion
- Increase pancreatic bicarbonate secretion
- Increase bile duct bicarbonate secretion
- Neutralisation
- Inhibits secretin secretion
Summary of CCK action
- Fat/amino acids in duodenum
- CCK release
- Decrease in gastric emptying
- Increase in pancreatic enzyme secretion
- Gallbladder contraction
- Relaxation of sphincter of Oddi
- Digestion
