Liver structure and function Flashcards
Where is the liver located?
Upper right quadrant of abdomen
What are the 2 major lobes of the liver?
Right and left
What are the 2 minor lobes of the liver?
Quadrate
Caudate
What lobe is superior, caudate or quadrate?
Caudate
What vessels are present at the porta?
Hepatic portal vein Hepatic artery Lymphatic vessels R and L hepatic ducts Hepatic nerve plexus
Where is the porta located?
Inferior surface of liver
What forms the common hepatic duct?
R and L hepatic ducts
What forms the common bile duct?
Common hepatic duct and cystic duct from gallbladder
How and where does the common bile duct enter the intestinal system?
Duodenum via the sphincter of Oddi
What covers the liver?
Connective tissue capsule and visceral peritoneum, except for the bare area
What is the bare area bare?
Small area on diaphragmatic surface surrounded by coronary ligament not covered
What does the capsule form at the porta?
Branching network of septa into the body of the liver for support
What happen to the septa in the liver?
Followed in by vessels, ducts and nerves before dividing the liver into hexagonal lobules
What is in the portal triad?
Hepatic portal venule
Hepatic arteriole
Hepatic duct
Also contains nerves and lymphatic vessels
Where is the portal triad located?
At each corner of the hexagonal lobule
What is in the centre of each lobule?
Central vein
What do central veins form?
Hepatic veins then IVC
What are hepatic cords?
Cords of hepatocytes spreading out from the central vein separated by sinusoids
What are sinusoids?
Blood channels travelling from portal venues to the central vein with a fenestrated membrane and epithelium
What lies between the cells in each hepatic cord?
Bile canaliculus
What are bile canaliculus?
Cleft like lumen running between hepatocytes that hepatocytes put their secretions into
What ar the 6 components of bile?
Bile acids Lecithin Cholesterol Bile pigments Toxic metals Bicarbonate
What is the function of bile acids, lecithin and cholesterol in bile?
Solubilise fat
What is the main bile pigment in bile?
Billirubin
Gives bile yellow colour
What is the function of bicarbonate in the bile?
Neutralisation of acid chyme
What secretes the components of bile?
All except bicarbonate secreted by hepatocytes
Bicarbonate secreted by duct cells
What are bile pigments?
Breakdown products of haemoglobin from old/damaged erythrocytes
What is bilirubin?
Dominant bile pigment
What is bilirubin present in?
Bile, faeces, urine
How does bilirubin give bile its colour?
Extracted from blood by hepatocytes and secreted into bile
How does bilirubin give faeces its colour?
Modified by bacterial enzymes to brown pigments
How does bilirubin give urine its colour?
Reabsorbed bilirubin excreted in urine
How are bile acids made?
Synthesised in hepatocytes from cholesterol
How much bile acid to we make a day and how much do we have stored?
0.5g
5g
What happens to bile acids before secretion?
Conjugated with glycine or taurine to form bile salts to increase
What happens to secreted bile salts?
Recycled via enterohepatic circulation
How big is the gallbladder?
8x4cm
What are the layers of the gallbladder wall?
Mucosa
Muscularis externa
Serosa
What is present in the mucosa of the gallbladder>
Rugae for expansion
What kind of muscle is present in the muscular externa of the gallbladder?
Smooth muscle
Where does bile from the gallbladder travel?
Cystic duct, common bile duct then duodenum via sphincter of Oddi
What controls bile secretion?
Sphincter of Oddi
What happens when the sphincter of Oddi is contracted?
Bile forced back into gallbladder
What is the function of the gallbladder?
Store and concentrate bile
How does the gallbladder concentrate bile?
By absorbing Na+ and H2O
How does bile enter the duodenum?
Fat in duodenum causes release of CCK causing sphincter to relax and gallbladder to contract
