Pancreas and Liver Flashcards
What is the role of the exocrine pancreas and liver
provide excretions (digestive enzymes) directly into intestine lumen, to digest CHO, protein, lipid in small intestine.
What is role of the Endocrine pancreas and liver
regulate blood borne energy substrate availability (post absorption) via hormones
glucose, fatty acids, ketone bodies and amino acids
Where is the pancreas situated and what is its role
digestive pro-enzymes are secreted via pancreatic duct to second part of duodenum
It lies posteriorly to the peritoneum , close to major blood vessels, difficult to access
Lies in a C shaped curve of duodenum with a head, neck, body, tail and uncinate process
what does the pancreatic duct combine with
common bile duct, and the three components of the sphincter of Oddi
Tell me about pancreatic blood supply
mainly via the splenic artery (from coeliac trunk), as well as the pancreatico-duodenal arteries (from SMA or coeliac trunk)
What are the primary functions of the exocrine pancreas
- neutralise acid
- deliver enzymes for macronutrient digestion in duodenum
What are Acinar cells
-mains secretory cells
clusters are connected by intercalated ducts
-converge on collecting duct
-lining cells add ions and secretions
Exocrine pancreas regulation of the cephalic phase
- Vagus nerve stimulates pancreatic secretions by releasing ACh and VIP
- 25% of pancreatic secretions
Exocrine pancreas regulation of the Gastric phase
- Mediated by vasovagal reflexes
- 10% pancreatic secretions
Exocrine pancreas regulation of the intestinal phase
controlled hormonally by secretin (in response to H+) and CCK (in response to fatty acids and monoacylglycerols)
65% pancreatic secretions
What are the role of Zymogen granules in acing cells
- House inactive and active digestive enzymes
- secreted in response to CCK (and VIP, gastric releasing peptide)
- when activated they are exocytosed into luminal space
How is the exocytosis regulated
hormonally and neurally
- CCK is released into interstitial space, enters blood stream, travels in circulation to pancreatic acing cells, binds with the CCKa receptors
- also binds to CCKa on vagal afferents giving efferent stimulation of pancreatic acinar cells via VIP
how are ions secreted
Ion + serous fluid secretion occurs in both acing and intercalated duct cells
How do acinar cells contribute to Ion secreting mechanisms
Basolateral CCK and ACh binding stimulates Cl- transport across apical membrane
Facilitates paracellular Na+ and water movement
How to intercalated ductal cells contribute to ion secreting mechanisms
-Secretin and ACh bind in ductal cells
-activates cystic fibrosis transmembrane conductance regulators, Cl- channels, Cl-HCO3- transporters
Transporters recycle Cl- and HCO3-
What happens when pancreatic secretion flow rate increases
HCO3- conc increases
Cl- conc decreases
HOWEVER
Na+ and K+ are not effected by flow rate
-Na+ is similar to plasma
-K+ slightly higher than plasma
Where is the liver situated
lies across the upper abdomen, under the diaphragm, surrounded by the peritoneum (excluding base area
What is the liver surrounded by
Glissons capsule
-thin connective tissue layer extensions into organ between lobules
How is the liver supplied
hepatic portal vein (nutrients from the stomach and gut)
hepatic artery supplies hepatocytes with oxygen
How is bile drained from the liver
canaculi that lie between the hepatocytes into bile ductules and eventually bile ducts
Tell me about the livers lobes
- right and left lobes (separated by falciform ligament)
- a quadrate lobe next to gallbladder
- prosterior surface shows the caudate lobe next to the IVC
What are the functions of the liver
- Synthesis and secretion of bile
- Storage of glucose, glycogen, proteins, vitamins and fats
- Detoxification of metabolic waste
- Synthesis of blood clotting and anticoagulant factors (fibrinogen and prothrombin)
What are the constituents involved in the synthesis of bile
bile pigments (bilirubin), cholesterol, phospholipids, fatty acids, water and electrolytes)
How are bile pigments derived
from the breakdown of haemoglobin Kupffer cells (fixed phagocytes) play a role aswell
