9 - Pancreas and the Liver Flashcards
What are the properties of chyme as it leaves the stomach and enters the duodenum?
- Hypertonic
- Low pH
- Partially digested
How does the duodenum protect itself from the acidic chyme?
How does the duodenum create an isotonic solution and deal with the other harmful factors of chyme?
- Duodenum draws water in from ECF as relatively permeable to water unlike the stomach
- Chyme release has to be controlled so duodenum not overwhelmed and draw in loads of water
What is the endocrine function of the duodenum?
Secretes:
- Secretin: in response to low pH of chyme. Acts on pancreas and liver to release aqueous bicarb
- CCK: in response to hypertonicity/small peptides and fats. Acts on enzyme portion of pancreas and gallbladder
What is the majority of the function of the pancreas and how is this function stimulated?
- 90% exocrine
- Gut hormones (CCK and secretin)
- Autonomic PS vagus
What part of the acinus in the pancrease produces bicarbonate and enzymes?
- Enzymes: acinar cells
- Aqueous bicarb: duct cells
What is the pathophysiology of pancreatitis?
- If protease become activated in the pancreas they start digesting and damaging it
- Can occur when obstruction
What are some of the zymogens in the pancreas?
- Trypsin
- Chymotrypsin
- Elastase
- Carboxypeptidase
How do pancreatic secretions reach the duodenum?
Pancreatic duct then the Ampulla of Vater
Where is bile produced and what does it contain?
- Liver and stored in the gall bladder
- Bile acids, salts, pigments and alkaline juice
- 250mls/1L a day
What are the roles of bile?
- Emulsify fats so larger surface area for enzymes
- Help absorption of digested fat by forming micelles
- Allows waste products, e.g bilirubin, to be excreted from the blood
What are some of the roles of the liver?
- Detoxification
- Energy metabolism
- Protein and lipid synthesis
Therefore, lots of RER and SER and lots of golgi
What is the macroanatomy of the liver?
GQ magazine
What is the structural and functional unit of the liver?
- Structural: lobule
- Functional: acinus that is a diamond
If a person had liver damage how could you tell histologically if it was due to toxins or ischaemia?
- Ischaemia: zone 3 damage as furthest from the blood supply
- Toxins: zone 1 most damage as reaches this first, e.g paracetamol OD
When is bile released from the gall bladder and what does the gall bladder do to the bile?
- When CCK released from duodenum the bile goes from common bile duct to ampulla of vater
- Concentrates the bile so this is why gallbladder stones can occur
What cells do bile salts and alkaline juice come from in the liver?
How are bile salts formed from bile acids and what is their structure?
- Bile acids are conjugated with amino acids to form salt
- Salts are amphipathic so can work on oil/water interface so micelles can form and fats can move through aqueous environment
How does fat get from the lumen of the intestine into the blood?
Go back via the thoracic duct
What is steatorrhoea?
- Undigested fat in faeces
- Smelly, pale, floating
- Due to issue with pancreatic lipases or bile salts so fat cannot be digested and absorbed properly
What is the enterohepatic circulation and it’s importance to bile salts?
- Allows bile salts to be recycled so don’t have to keep conjugating lots of bile acids.
- Fibre lowers cholesterol as it binds to bile salts and causes them to be lost in the faeces so more have to be synthesised in the liver using cholesterol
