Digestion enzyme stuff first aid Flashcards
alpha amylase does what and is secreted from where
starch digestion
Lipase and phospholipase do what
Fat digestion
Proteases do what?
Proten digestion
Trypsinogen
Converted to trypsin, then activates other coenzymes and creates more trypsin.
Salivary amylase’s role in carbohydrate digestion
Starts the process by hydrolyzing alpha 1,4 linkages to yield disaccharides (maltose and alpha limit dextrin,maltotriose)
Pancreatic amylase
hydrolyzes starch to oligosaccharides and disacchardies
Oligosaccharide hydrolase
These are located at the brush border of the intestines, teh rate limiting step in carbohydrate digestion, they produce monosaccharides from the disaccharides and oligosaccharides.
Carbohydrate absorption is interesting. Only monosaccharides like- Glucose, galactose, fructose- are absorbed by enterocytes. After that, GLucose and galactose are taken up by what?
SGLT-1
Fructose is taken up by facilitated diffusion by
GLUT-5
Glucose, Galactose, and Fructose are all transported into the blood by
GLUT-2
What are the two types of digestive enzymes>
1) Luminal
2) Membrane Enzymes
Basal cells in enterocytes are located where?
Crypts…Stem cells move up the villi and differentiate as they do. Stem cells migrate asymmetrically
Gut cells slough off at what rate
Every 3-5 days. Newly differentiated stem cells take their place.
Which portion of the gut is integral to the reabsorption of vitamin B12 and Bile Acid.
Ileum
How much of the gut can be removed without any major impact
60-70 percent
What are the barriers to absorption in the enterocyte?
1) Unstirred water layer, this is an especially formidable barrier to fats
2) Glycocalx- no idea what it does, doesnt matter
3) Microvilli Membrane (enterocyte membrane)
4) Cytoplasm
5) Basolateral Membrane
6) Basement Membrane
7) Capillary wall (fenestration)
Fat cells leave the enterocytes in what?
Chylomicrons
Glucose absorption requires what?
Oxygen
Starch and Glycogen are first broken down by salivary amylase into?
1) alpha dextrins (1,4 and 1,6)
2) Maltotriose
3) Maltose
Alpha dextrin 1,4 is digested mainly by what membrane enzyme?
Isomaltase
Alpha 1,6 digested by
Glycoamylase (60)
Sucrase (20)
Isomaltase (20)
Maltotriose digested by?
G, S I (25, 25, 50)
Maltose digested by?
G, S, I (25, 25, 50)
Glucose and Galactose taken into the enterocytes by
SGLT-1
See carriers for carb absorption slide and recognize that SGLT-1 is responsible for transporting Na and Glucose or Galactose into the cell. Na then is pumped out via the Na/K ATPase transporter,,,so this SLGT-1 transport depends on Na/K working and I guess vice versa. The transporter itself dumps what its carrying and moves back to the apical membrane.
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WHat the fuck is GLUT-5
carries fructose into the cell
What the fuck is GLUT-2
Carries all of the simple sugar, Glu- Gal- Fru, across the basolateral membrane and out of the enterocyte.
Knowing what we know about these transporters, what would happen to the amount of glucose being digested if you added a bunch of galactose into the system?
The amount of glucose in the system would go down because you have two things competing for the same transporter
Most common enzyme deficiency?
Lactase deficiency
What begins the digestion of protein?
Pepsin
What kind of enzyme is pepsin
Endopeptidase (cleaves interior peptide linkages)
In regards to protein absorption, remember that the absorption of peptides is separate from the absorption of free amino acids
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What are the 3 major enzymes of fat digestion
1) Pancreatic Lipase
2) Cholesterolester Hydrolase
3) Phospholipase A2
Pancreatic Lipase does what?
Breaks up triglycerides into 2 Monoglyceride and 2 free fatty acids
Cholesterolester Hydrolase does what
Cleaves the fatty acids from the 3 position of cholesterol and fat soluble vitamins
Phospholipase A2 does what?
Lecithin to lysolecithin
