Session 6 Flashcards
(11 cards)
- Describe the key properties of chyme leaving the stomach (3) LO
- What does the statement Chyme release must be controlled so as not to overwhelm duodenum mean
- What combats the low pH & partially digested (still many proteins fats & CHOs to breakdown) food.
Acidic
HCO3- pancreas, liver and duodenal mucosa
HCO3- produced during the production of Gastric Acid
Hypertonic
osmotic movement of water into the duodenum across its wall (ECF, stomach impermeable)
Partly digested
Completed by enzymes from the pancreas & duodenal mucosa, with bile acids from the liver
- Do not want to drop you blood pressure
- Secretions from the Pancreas ( Enzymes & bicarbonate) and Liver ( bicarbonate & bile)
- What does the duodenum secrete? And what stimulates its to secrete?
- secretin & CCK, response to chyme
- Function of Secretin? (1)
- Function of CCK (2)
- Secretin acts on pancreas -> release an aqueous bicarbonate (HCO3-) component
- CCK -> pancreas -> enzyme
CCK -> gallbladder (contracts) & relaxes sphincter of oddi
Secreting wants to SOOTH the acid
CCK everything else
- Secretin released from duodenum in response to?
- cholecystokinin (= bile sack move)-released from duodenum in response to?
List the secretions of the exocrine pancreas LO
- ? % of the pancreas is exocrine function
- Pancreatic secretions (exocrine function) stimulated via? (2)
- List the secretions of the exocrine pancreas LO
- Low pH of chyme
- hypertonicity/small peptides/fats within chyme in duodenum
- 90%, much smaller proportion for endocrine function
- gut hormones (secretin & CCK) but also autonomics
– Sympathetic inhibits
– Parasympathetic (vagus) stimulates - – Amylases & lipases (active-ready to go!)
– Proteases (inactive): (active)
– Trypsin
– Chymotrypsin
– Elastase
– Carboxypeptidase
- bicarbonate
- What does CCK act on to stimulate the release of enzymes?
- What Enzymes does it produce?
- Where are these Enzymes produced? (Inactive)
- Function of zymogen granules?
- What cells release bicarbonate? Function of these cells?
- CCK (& vagus) stimulate acini (singlular = acinus) to produce enzymes
- – Amylases & lipases (active-ready to go!)
– Proteases (inactive): (active)
– Trypsin
– Chymotrypsin
– Elastase
– Carboxypeptidase - acinar cells are concentrated & stored in zymogen granules
- Zymogen granules contain zymogen (e.g. trypsinogen; which is converted to trypsin in intestinal lumen)
-
Duct cells secrete
– Aqueous component (isotonic)
– Bicarbonate
• Will act to neutralise the acidic chyme
Describe the control of pancreatic and biliary secretion LO
- Pancreatic secretions reach the duodenum via?
Describe how the microscopic structure of the liver relates to its functions LO
- Chief functional cell of liver? Why?
- Mucroscopically the liver is seen to have lots of ? why?
- The liver contains?
- What drains from the gut to the liver and vice versa
- What are the structural components of the liver called?
- The pancreatic duct and Ampulla of Vater
- Hepatocytes, form 80% of liver mass
- rough/smooth ER & Stacks of golgi membranes
producing proteins & lipids for export
- lots of glycogen
- All blood from gut drains into liver
– Portal vein
Bile drains from liver in to gut - Lobules
- Describe the structure of the liver lobule
- State the difference in flow in the triad
- • Hexagonal
• Triad of structures at each corner:
- Portal vein (branch)
- Hepatic artery (branch)
- Bile duct
- Central vein in middle
- Blood enters a lobule via hepatic artery & portal vein (branches of)
- Arterial & venous blood flow towards the central venous vein
But
The bile flows out in the opposite direction
Arterial and venous blood through sinusoids
Bile through canaliculi
- What is the functional area of the lobule called
- Where does blood drain from?
- Acinus
Q. What does this drainage system result in
Q. State why this structure has clinical significance in relationship to pathological processes
Describe the digestive functions of the liver & the components of bile LO
Q. In response to chyme what does the liver secrete?
Q. Where is it stored? How much is secreted a day?
Q. What are the components of bile?
A. Creates a series of zones 1,2,3 corresponding to distance from arterial blood supply
A. Toxic substances are most likely to damage cells in zone one as blood flows first from the periphery then to the central vein.
Ischaemia is most likely to effect cells in zone 3 as they are the last/ furthest to receive the blood supply
A. Bile
A. Gallbladder, 250mL-1000 mL/day into the duodenum
A. Bile is either bile-acid dependent or independent
- Bile acids & bile pigments (secreted into canaliculi by hepatocytes)
– Alkaline solution (secreted by bile duct cells -> Stimulated by Secretin)
- Function of bile ?
(Describe the secretion of bile acids and the entero-hepatic circulation of bile acids LO
Describe the function of the gall bladder and the relationship to the formation of gallstones LO)
- What is bile created by? Describe its supply and demand.
- What is the function of the gall bladder
- CCK stimulates contraction of the gall bladder, bile secreted via?
- What does the bile contain?
- What are bile salts?
- Give two examples?
- What are bile salts conjugated with?
- Bile emulsifiers fats in the duodenum so that they can be readily digestedby lipase secreted by the pancreas
- Bile is created by hepatocytes & duct cells in the liver
-
concentrates bile ( removes water/ ions) -> can lead to GALLSTONES
CCK released from duodenum stimulates gallbladder contraction -> emulsify fats aiding their digestion - Common bile duct, then Ampulla of Vater into duodenum
- BAP
Bile acid
Alkaline
Bile pigments - Conjugated bile acids
- _Cholic acid
Chenodeoxycolic_
( further bile acids formed in the gut)n - Aa e.g. glycine, taurine
Why conjugate?
• Bile acids are not always soluble at duodenal pHs (functionally useless)
• Bile salts have an amphipathic structure Hydrophilic end (water soluble) Hydrophobic end (lipid solube) Act at oil/water interface
• Bile salts allow emulsification of dietary lipids
