Pancreas And Liver Flashcards
What are Brunner’s glands?
Glands in duodenum that secrete alkaline mucosa which protects the cells
Lining the duodenum from Acidic chyme
Mechanisms that allow for further digestion of chyme within duodenum
Hypertonic - stomach wall largely impermeable to water but duodenum relatively permeable so water drawn in from ECF/ circulation to dilute chyme. Chyme release controlled so duodenum not overwhelmed - now isotonic to plasma
Low PH- duodenum secretes secretin (acts on pancreas/ liver -> HcO3- aq) and CCK (acts pancreas -> enzymatic secretion & gallbladder -> contracts & sphincter of oddi -> relaxation)
Partially digested - still many proteins, fats, CHOs to breakdown. Liver secretes bile (stored gallbladder) in response chyme, bile acids and bile pigments, alkaline solution. Emulsifiers fats.
What’s an acina, what cells make it up?
At the ends of pancreatic ducts surround the islets of langerhans
Made up of acinar cells where enzymes and inactive zymogen granules stored, centroacinar cells and duct cells (produce HCO3- aq)
What stimulates acini to secrete and what do they secrete?
CCK & vagus nerves stimulate acini to produce enzymes (active amylases and lipases) (proteases as zymogen granules)
Proteases are activated when hit walls of duodenum -> trypsin, chymotrypsin, elastase, carboxypeptidase (can be activated in pancreas when pressure builds up -> pancreatitis)
How to pancreatic secretions reach the duodenum?
Through pancreatic duct
Ampulla of vater
Sphincter of oddi
What does the liver secrete in response to chyme?
Bike - bike acids and bile pigments in alkaline solution - emulsify fat and aids in absorption of end products through intestinal wall
What are the four lobes of the liver, what are their functions?
Biggest- right
Opposite- left
Inferior - quadrate
Superior- caudate
Same functionally
What are the triad of structures at the corner of each hexagonal liver lobule?
Portal vein branch
Hepatic artery branch
Bile duct branch
How does blood and bile move in a liver lobule?
Blood flows in from branches of the portal vein and hepatic artery and runs along sinusoids to drain into the central vein of the lobule
Bile secreted from hepatocytes and duct cells and moves along canaliculus to bile duct
What is the functional area of a lobule called? Where is it found? What are the zones of it and what is their significance?
Acinus
Found centrally between a right and left lobule
Zones 1-3 corresponding to distance from blood supply
Zone 1 - 1st to revive oxygenated blood (most central) but also to receive toxins so if most liver damage here probably a toxic cause
Zone 3 - (last to receive O2 blood) most vulnerable to hypoxia. Damage with ischaemic cause.
What is stored in the gallbladder, how is it changed here and how is it secreted?
Bile is concentrated (removes water/ ions) can lead to gallstones
CCK from duodenum stimulates gallbladder to contract -> common bile duct -> ampulla of vater -> sphincter of oddi-> duodenum
What’s the difference between bile salts and bile acids?
Bile salts are conjugated bile acids (AA added)
Bile salts are more soluble in duodenal pH as have amphipathic structure - hydrophilic end and hydrophobic end
How do bile salts help digestion of lipids?
Bile salts:
Emulsify fat droplets -> create micelles from lipid products (vehicle for transporting hydrophobic molecules) -> enterocytes -> lipids diffuse in but bile salts do not
Lipid products: cholesterol, monoglycerides, free FAs
How are bile salts recycled? What’s the name of this process?
Don’t get absorbed into cytosol of enterocytes so remain in gut and are reabsorbed in terminal ileum -> portal blood-> liver
Entero-hepatic circulation of bile salts
How do enterocytes form chylomicrons?
Lipid molecules re-estified -> triglycerides/ phospholipids/ cholesterol
Packed with apoproteins -> chylomicrons -> exocytosed from basolateral membrane of enterocyte -> lymphatic capillaries -> thoracic duct -> circulation
