Week 5 - liver and pancreas Flashcards
Explain the location of the liver
- right upper quadrant of abdomen
- starts in 5th intercostalspace
- ends kust below ribcage
What is the blood supply?
Duovenous
- hepatic artery and portal vein enter liver through porta hepatis
- leaves as deoxygenated blood, back to heart via hepatic vein
Function of the liver
- fat metabolism
- heat generating
- Carbohydrate metabolism
- protein metabolism
- storage
- intermediary metabolism
- secretion
- removal of RBC
What are hepatocytes ?
- large polyhedral epithelial cells, round nuclei, perminant nucleoli
- more than half contain twice the normal complement of chromosomes
- binucleate cells are common
- constantly porduce bile
How is the liver organised?
- into lobules
- which divide into hepatic sinusoids
What is a lobules?
Basic structural unit of liver, lobules made up of hepatic sinusoids
What are hepatic sinusoids?
Low-resistance system of vascular channels allowing blood to come in contact with hepatocytes over huge area
What does the portal tract consist of?
Portal vein
Atria
Bile duct
Hepatic lobule blood flow
- From portal vein and hepatic artery in portal tract to central hepatic veins
- slow flow along sinusoids lined with fenestrated endothelial cells
What does the close associaton of blood to hepatocytes allow for?
Absorption of nutrients and secretion fo hepatic porducts
What are the additional cells lining sinusoids?
Kuppfer cells
Hepatic stellate cells
What are Kuppfer cells
What are hepatic stellate cells?
By what cells is bile produced?
By all hepatocytes - groces in plasma membrane of hepatocytes form bile canliculi - fuse to form canals of hering
What is bile
- acids in lipid digestion in small intestine
- contains water, bile salts, cholesterol, bilirubin
- synthesised by all hepatocytes
- secreted into canaliculi formed by plasma membranes of adjacent hepatocytes
- contain ATPase which suggests bile secretion is energy dependent
- contain alkaline phosphatase
name the billary tree
Bile caniculi -> canals of hering -> bile ductules -> bile ducts -> hepatic duct -> common bile duct -> ampulla of vater -> duodenum
what do intrahepatic bile collecting systems merge into?
Single large common hepatic duct
What is the common hepatic duct joined by when leaving the liver?
Cystic duct which drains gall bladder, forms common bile duct
What is the gall bladder?
Muscular sac lined by simple columnar epithelium
100 mL capacity in human
Why is it useful to consider different zones along sinusoids?
Different funcitons have different oxygen requirements
Which zone is nearest to the hepatic vein?
Zone 3
Which zone is nearest to the portal vein?
Zone 1(highest oxygen levels)
What is the pancreas
Soft organ sitting high in the stomach
What are the funcitons of the pancreas
Hetrocrine functions
1. Endocrine (1%) - islet of langerhans- blood sugar regulating
2. Exocrine (99%) - digestion
Acinar cells
Panacreatic juice
What is the oancreatic juice made up of, what is its funciton
What do alpha cells produce?
What do beta cells produce?
How is hormone regulation of pancreatic secretion done?
- continous but rate modulated by hormonal and nervous influences
What is secretin
what is CCK
What is gastrin
What enzymes are contained in the pancreatic juice
Why doesnt the pancreas digest itself?
- enzymes secreted as proenzymes (zygmogens)
- trysinogen acitvated by enteropeptidase in duodenum
Tryspin activtes proenzymes - trypsin can be inacticated
How do pancreatic acini look like?
Lumen (acini)
Intercalated duct
Intralobular duct
Interlobular duct
What pancreatic cell types make zymogens
Acinar cells
Where do pancreatic juices enter the intestine?
Duodenum
Which ell of the exocrine pancreas make somatostatin?
Delta
Where are the endocrine cells of the pancreas located?
Islets of Langerhans
