5: Pancreas & Liver Flashcards
Where does the stomach empty chyme into?
Duodenum
What are the key properties of chyme? (3 things)
- Acidic
- Hypertonic
- Partly digested
How is the acidity of chyme corrected?
By HCO3- secreted from pancreas + liver + duodenal mucosa
How is the hypertonicity of chyme corrected?
By osmotic movement of water into duodenum across wall
How is the digestion of the partly digested chyme completed?
By enzymes from pancreas
What are the 2 components of Bile?
- Bile Acid dependant
- Bile Acid independant
What are the Bile Acid Dependant components secreted by?
Hepatocytes
Secreted into canaliculi (of bone)
What are the Bile Acid Dependant components?
- Bile acids (cholic acid)
- Cholesterol
- Bile pigments (bilirubin)
What are the Bile Acid Independant components secreted from?
Cells lining intra-hepatic bile ducts
What are the Bile Acid Independant components?
Alkaline juice (HCO3-)
What is the basic functional unit of the liver?
Lobule surrounding a central vein
- Vein drains blood from liver → systemic veins
How does blood flow through a hepatic lobule?
- Blood from Hepatic Portal Vein + Hepatic Vein → Enters sinusoids @ periphery of lube
- Blood flows through sinusoids (lined by hepatocytes) → Central Vein
What is the duodenum response to gastric emptying? (3 steps)
- Duodenum secretes Cholecystokinin (CKK)
- CKK stimulates gall bladder contraction
- This ejects concentrated bile acids with enzymes from pancreas
What is the pancreas and liver response to gastric emptying?
Alkali released rom pancreas and liver in response to secretin
Where does the Pancreas + Bile ducts release their bile acids through?
Through Ampula of Vater into small intestine
What happens to blood returning from digestive tract? (3 steps)
- Blood enters Hepatic Portal Blood
- Hepatocytes actively take up bile acids
- Hepatocytes re-secrete bile acids into canaliculi
What happens to bile acids in between meals?
Returned to liver → secreted into canaliculi → stored in gall bladder until needed
How is bile acid concentrated in the gall bladder?
Salt and water transported across gall bladder epithelium → reduces volume
What does concentrated bile acids increase the risk of?
Gall stones
What are the symptoms of gall stones?
Usually asymptomatic
BUT if they move into neck of gall bladder / biliary tree → very painful biliary colic / obstruction
Followed by:
- Inflammation (cholecystitis)
- Gall bladder infection
When is the pain for gall stones worse?
After eating because Cholecystokinin (CKK) causes gall bladder to contract
What are the exocrine pancreas secretions? (2 things)
- Alkaline juice (HCO3-)
- Enzymes:
- Proteases
- Amylases
- Lipases
What is the mechanism of alkaline juice secretion (HCO3-)?
- Na-K ATPase pump sets up Na+ concentration gradient
- H+ ions exported from Duct Cell → ECF using Na+ gradient
- H+ ions combine with HCO3- → H2O + CO2 → taken up into Duct Cell
- H2O + CO2 → reform HCO3 + H+ inside Duct Cell
- HCO3+ exported into Duct Lumen
- H+ recycled → carrys more HCO3+ from ECF to lumen
What is Secretin?
Hormone that stimulates secretion of:
- Pancreatic Juice
- Bile (from Liver)
How and where is secretin released?
Duodenum
In response to low pH
What facilitates the action of secretin?
Cholecystokinin (CKK)
What are the 2 types of pancreatic secretions?
- Acinar
- Duct