Liver Structure and Function Flashcards
(24 cards)
- T/F: Liver is the largest organ in the body weighing 1.4kg.
- Where is it located?
- Name it’s major and minor lobes.
- True
- Upper right quadrant of abdomen (tucked against inferior surface if diaphragm)
- Two major lobes: right > left. 2 minor lobes: caudate & quadrate
Where do blood and lymphatic vessels, ducts & nerves (hepatic nerve plexus) enter/exit?
Porta on inferior surface
What is found in the centre of each lobule?
Central veins that drain into hepatic veins which then drains into IVC.
What radiates out from central veins (like spokes of wheel)?
Hepatic cords
- What are hepatic cords composed of?
- What lies between cells within each cord?
- What are the spaces between hepatic cords called?
- Hepatocytes (functional cells of liver)
- Bile canaliculus (cleft-like lumen)
- Hepatic sinusoids (blood channels)
What is a portal triad and where is located?
Triad consist of hepatic portal vein, hepatic artery, hepatic duct. Located at each corner of hexagonal lobule (also nerves & lymph vessels).
What is the function of liver?
Alimentary role of liver = production & secretion of bile.
- What are the 6 components of bile?
2. T/F: all of the 6 components are secreted by hepatocytes.
- Bile acids, lecithin, cholesterol (synthesised in liver, soluble fat). Bile pigments (bilirubin from Hb). Toxic metals (detoxified in liver). Bicarbonate (neutralisation of acid chyme).
- No, only 1-5 are. bicarbonate is secreted by duct cells.
What are bile pigments?
Breakdown products of Hb from old/damaged erythrocytes.
Where is bilirubin (predominant bile pigment) extracted from and secreted into?
Extracted from blood by hepatocytes & secreted into bile (yellow bile)
Bilirubin is yellow but why does your poo look brown?
Looks brown because it is modified by bacterial enzymes.
Why is urine yellow?
Reabsorbed bilirubin (yellow) excreted in urine.
Bile acids are synthesised where and from what?
In liver from cholesterol (0.5g/day excreted (that’s 5% of total production)).
Before secretion bile acids are conjugated with what to form what and why?
Glycine or taurine to form bile salts that increases solubility.
How are secreted bile salts recycled?
Via enterohepatic circulation. Liver to bile duct to duodenum to ileum to hepatic portal vein to liver etc..
What is found on the inferior surface of liver?
Gallbladder
Describe the layers of gallbladder wall.
Mucosa (folded into rugae which can expand). Muscularis made of smooth muscle that produces contraction. Serosa (connective tissue).
What drains gallbladder?
Cystic duct which then drains into common bile duct.
How is bile secretion reduced/stopped?
Sphincter of Oddi: controls release of bile & pancreatic juice into duodenum. When contracted (closed), bile forced back into gallbladder.
How is bile secretion increased/stimulated?
Fat in duodenum stimulates release of CCK which then relaxes sphincter of Oddi & makes gallbladder contracts. So, bile is discharged into duodenum where it solubilises fat. CCK stimulates secretion of bile & pancreatic enzyme.
What is the function of gallbladder?
Concentrates bile 5-20 times (absorbs Na+ & H2O).
Liver covered by connective tissue capsule and visceral peritoneum except for?
Bare area (small area on diaphragmatic surface surrounded by coronary ligament)
What follows septa throughout liver and what does it divide liver into?
At the porta, there is a connective tissue branching through the liver, which is called septa (used for support). Vessels, ducts and nerves follow septa throughout liver.
Septa divide liver into hexagonal lobules
Outline how blood from alimentary canal flow.
From alimentary canal, O2-depleted/nutrient-rich blood flows into hepatic portal vein which together with O2-rich/nutrient-depleted blood (to oxygenate hepatocytes) from hepatic artery drains into hepatic sinusoids which either drains into central veins > hepatic veins > IVC. Or Hepatic sinusoids <> hepatocytes > canaliculi > hepatic ducts.
