de lisle nutrient, pancreas Flashcards
what surface of the pancreatic acinar cell of the proximal duct is the CFTR?
apical
CFTR secretes and then reabsorbs Cl, as it is reabsorbed what ion passes from cell to the lumen? Where does this occur?
HCO3 in the proximal duct
In the distal duct, how does the CFTR channel change?
it becomes basically an HCO3 channel
When CFTR is defective?
HCO3 aggregate in the duct and the exocrine pancreas is autodigested. Can be treated with porcine pancreas
What form of sugars are absorbed in the small intestine?
monosaccharides
salivary and Pancreatic alpha amylase is broken down itno
amylose
brush border enzymes convert _______saccharidases and __saccharidases to monosaccharidases for absorption
oligo and di
where is lactase contained?
brush border of enterocyte
where does amylase cleave?
alpha 1,4
What bond can’t amylase break down?
1,6
amylase hydrolyzes starch to alpha______, _______ose, and _______ose
alpha dextrin
maltotriose
maltose
COOh digestion and Absorption is ______dependent through which transporters?
Sodium, SGLT1
How do glucose, galactose, fructose enter the cell and through which transporter?
facilitated diffusion
via GLUT 5 n the intestine
Through which transporter do monosaccharides exit the cell basolaterally into the blood and serosal space?
GLUT2 (sodium dependent, facilitated diffusion)
what proteins control paracellular Na+ permeability in the small intestine?
Claudin
part of the zonula occludens
claudin type determines the permeability
why does the intestine need to paracellularly recycle sodium?
to allow for sodium cotransport of Glucose, AA, Lipid, and Bile Acid reabsorption
where does protein digestion start and where does majority occur?
starts in the stomach with pepsin, continues in the intestines via pancreatic proteases.
Pancreatic Proteases (pro form/zymogen)
trypsinogen Chymotrypsinogen Proelastase Procarboxy A Procarboxy B
Which pancreatic proteases produce free amino acids and what does that indicate about where they cleave?
Carboxypeptidase A and B
they cleave single terminal AAs
Which pancreatic proteases produce free amino acids and what does that indicate about where they cleave?
Carboxypeptidase A and B
they cleave single terminal AAs
Where is enterokinase selectively expressed and what does it act on?
brush border membrane enzyme
acts on trypsinogen
Trypsin–Basic terminal AA– broken down by
Carboxy B
Chymotrypsin results in peptide ith Neutral AA
Carbozy A
How are amino acids absorbed by the intestinal epithelium ?
Na depedent exchanger
How are small peptides absorbed into the intestinal cells (a difference between COOH and proteins)
PEPT1 a H+ cotransporter
H+ is recycled via sodium hydrogen exchanger
where are CCK cells (I cells)?
Duodenum
Enterocytes release CCK-RP when stimulated by ___ and ____
Fatty acids and Amino Acids
what peptide does the pancreas release to stimulate the I cell?
Monitor peptide
When Trypsin is bound to protein after a high protein meal what happens to CCK?
Trypsin usually inhibits the release of CCK via the I cell, so when the trypsin is bound to protein, it can’t inhibit the I cell leading to release of CCK and subsequent stimulation of the gallbladder and pancreas, decrease gastric emptying
Major lipolytic enzyme is_____ and released by____ and requires?
Pancreatic Lipase requires colipase, neutral pH, bile salts
Where do lipases act?
lipid-water interface of the triglyceride droplet
What is the role of bile salts in assisting with the binding of colipase to the lipase at the droplet interface?
Bile salts emulsify lipids into micelles
What is unique about the absorption short and medium triglycerides?
They can be absorbed into the portal venous blood directly
Long chain fatty acids have to be absorbed then reesterified and packaged with proteins into a _____
chylomicron
Short and medium chain TGs go to the portal venous system whereas the LCFA chylomicrons go to the
chyle lymphatics (via the lacteal)
what is procolipase activated by to form colipase and enterostatin (satiety agent)
trypsin
hydrophobic side of bile salt is facing______ and is comprised of
facing inside
comprised of cholesterol (TAG tails)
Mixed Micelle are
DAG, FA, MAG, lysophosphitic acid, bile salts
RER produces what protein necessary for formation of chylomicrons?
ApoB
constitutive exocytosis
chylomicrons made and immediately go to lymphatics
are the brush border hydrolases higher in the crypts or villi?
in the villi
is nutrient transport higher in the villus or crypt?
higher in the villus
is permeability higher in villus or crypt
higher in the crypt
Bile salt and B12 absorption mainly in
Terminal ileum
Hydrolases and Nutrient transporters are highest in what part of the small intestine?
The brush border of the microvilli of the Jejunum
Iron absorption is mainly in the
duodenum
