Pancreas liver, hormonal control Flashcards
exopeptidase
An exopeptidase is any peptidase that catalyses the cleavage of the terminal peptide bond; the process releases a single amino acid or dipeptide from the peptide chain.
Depending on whether the amino acid is released from the amino or the carboxy terminal.
Aminopeptidase, an enzyme in the brush border of the small intestine, will cleave a single amino acid from the amino terminal
Carboxypeptidase, which is a digestive enzyme present in pancreatic juice, will cleave a single amino acid from the carboxylic end of the peptide.
Endopeptidase
break peptide bonds of nonterminal amino acids
Functions of liver
Glycogen storage Lipid metabolism Transamination Deamination Detoxification Lactate removal Heat generation Iron storage Bile production
Label parts of liver
See hand out
What happens in the The Ornithine Cycle
Ammonia is converted to less toxic urea
What is the equation for the ornithine cycle
2NH3 + CO2 –> CO(NH2)2 + H2O
Draw the ornithine cycle
see notes
How does it take place
This takes place via a number of reactions partly in cytosol and partly in mitochondria
How is ammonia converted
Converted to urea by addition of carbon dioxide in the ornithine cycle
What happens after
Urea passed back into the blood and carried to the kidneys where it’s excreted
Why can urea be passed into the bloodv
Urea is less soluble and less toxic than ammonia so it can be passed back into the blood to the kidneys
What filters the urea? where is it stored and in what form
The kidneys filter out the urea from the blood and store it as urine in the bladder
What is the word formula for the ornithien cycle
Ammonia + carbon dioxide –> urea + water
Label pancreas
See hand out
What are anicar cells
Cells called acinar cells within the pancreas produce digestive enzymes
Found in small groups surrounding tiny tubules
The tubules join up to make the pancreatic duct
Which carries the pancreatic juice to the duodenum
Over 90% of pancreas related to digestive enzyme production
Pancreatic proteases (such as trypsinogen (precursor for), chymotrypsin and carboxypeptidase) - which help to digest proteins.
Pancreatic amylase - which helps to digest carbohydrates (sugars).
Pancreatic lipase - which helps to digest fat.
Hydrogencarbonate ions make the fluid alkaline
Name the cells of the pancreas
see handout
Describe Gastrin
- Produced by special cells in the lining of the cardiac region of the stomach.
- Produced in response to the physical stimulation due to presence of food as well as to the chemical stimulation by protein .
- Also can be produced by the anticipation (thought) of eating (nervous stimulation).
- When gastrin is released, it stimulates the production of gastric juice by the gastric glands.
- When there is sufficient gastric juice present, the production of gastrin will stop and then so will the secretion of gastric juice
Cholecystokinin (CCK)
Produced by special cells in the lining of the duodenum.
Cholecystokinin is produced by the duodenum in response to the physical presence of chyme, as well as to the chemical presence of fat and protein molecules.
This hormone also goes by the name Pancreozymin.
It controls the release of bile from the liver/gallbladder by contraction of the gall bladder
Along with Secretin, it also stimulates the release of pancreatic juice from the pancreas – mainly the release of pancreatic enzymes.
It also controls the emptying of the stomach.
Secretin
Produced by special cells in the lining of the duodenum.
Produced in response to the presence of acidic chyme in the duodenum.
When secretin is released it stimulates the production of sodium bicarbonate by the pancreas and secretion of the pancreatic juice
Sodium bicarbonate neutralizes and buffers the acidic chyme so that the pH changes to neutral - 8
When the pH of the chyme in the duodenum reaches ~8, the production of secretin will stop and so will the release of pancreatic juice containing sodium bicarbonate
What stimulates release of bile?
Cholecystokinin (CCK)
What stimulates release of sodium bicarbonate?
Secretin
What stimulate release of gastric juices?
Gastrin
