Term
| Advantages & disadvantages of cellulose in diet. |
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Definition
A: regular bowel movements, prevent constipation
D: diarrhea? |
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Term
| What enzymes are secreted in the mouth? |
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Definition
Salivary a-amylase -> carbs
lingual lipase -> lipids |
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Term
| What glands/organs secrete enzymes that digest starches? What do they digest them into? |
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Definition
Salivary glands -> maltose
Pancreas -> maltose
Intestinal mucosa -> Glu, Fru, Gal |
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Term
| What gastric/pancreatic secretions digest protein? |
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Definition
Stomach: Pepsins -> smaller peptide chains
Pancreas: Trypsin (activated by Ek), Chymotrypsins and Elastase (activated by Trypsin) -> smaller peptide chains |
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Term
| What is the importance of pancreatic trypsin inhibitor? |
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Definition
| Trypsin would injure the pancreas if it was in its active form, therefore it's activated in the SI by enterokinase. |
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Term
| What are the lipases we need to know? |
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Definition
mouth: lingual lipase
stomach: gastric lipase
small intestine: pancreatic lipase and co-lipase |
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Term
| Release of CCK by the duodenum causes |
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Definition
gallbladder constriction
spincter of oddi relaxation
pancreatic enzyme release |
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Term
| Pancreatic lipase cleaves TGs into |
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Definition
|
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Term
| cholesterol esterase cleaves cholesterol esters into |
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Definition
cholesterol and acid
(also cleaves fat soluble vitamins like D & E) |
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Term
| Phospholipase A2 is activated by trypsin and cleaves phospholipids like lecithin into |
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Definition
lysolecithin.
(this probably isn't exam important) |
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Term
| Co-lipase is activated by |
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Definition
|
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Term
| Pancreatic lipase is secreted in its _____ form. |
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Definition
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Term
| What's the most important lipase relationship? |
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Definition
| pancreatic lipase and co-lipase!!! |
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Term
| What's important about the SI structure? |
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Definition
microvilli are 1 cell layer thick
allows for easy absorption
crypt lumen is secretory area
digestion of carbs/proteins happens on the lumenal side right on the cells before they're absorbed |
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Term
| What's important about the unstirred layer? |
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Definition
| It protects the single cell villous lining from the stuff flowing in the SI lumen. |
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Term
| How is a micelle formed? What are its benefits? |
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Definition
When pancreatic lipase gets into the emulsion to do its job, the whole thing is called a micelle.
Micelles allow the hydrophobic lipids to pass the unstirred water layer. |
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Term
| What causes intestinal gas formation? |
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Definition
| unabsorbed carbs that are digested by colon bacteria. |
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Term
| What might happen if you remove the gall bladder? |
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Definition
| There would be no bile storage. Liver would still make bile, but not enough would be released when needed so fat consumption would have to be planned. |
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Term
| What would happen if the common bile duct was occluded? |
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Definition
Backup of bile in the liver.
Jaundice (high blood bilirubin)
Fat in poops
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Term
| What would happen if the pancreatic duct was occluded? |
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Definition
Pancreatic enzymes wouldn't be released into the duodenum.
Malabsorption
Weird poops
Pancreatitis and probably eventual death. |
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Term
What does enterokinase do?
Where is it found? |
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Definition
activates Trypsin
secreted by crypts of lieberkuhn in duodenum |
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Term
| Glu and Gal go through the _____ transporter. |
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Definition
GLUT2
(Na dependent secondary active transport) |
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Term
| Why does a low sodium diet not affect the Na/K ATPase transporter that the Glu-Na transporter depends on? |
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Definition
| Na is released in all the secretions preceeding the SI anyway. |
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Term
| Fructose uses specific GLUT5 carrier proteins and is imported by |
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Definition
|
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Term
| What are the brush border saccharidases and their targets and products? |
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Definition
Maltase -> maltose to glucose
Isomaltase -> isomaltose to glucose
Lactase -> lactose to glu and gal
Sucrase -> sucrose to glu and fru |
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Term
| Dissaccharide deficiency causes... |
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Definition
malabsorption of carbs
osmotic effects of undigested sugars retains water in the GI lumen
diarrhea |
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Term
| How are di- and tri-peptides absorbe into cell? |
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Definition
| specific peptide transport proteins |
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Term
| Amino acids are absorbed into the cell via |
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Definition
|
|
Term
| Know these 4 brush border proteases... dumbass. |
|
Definition
Trypsin
Chymotrypin
Carboxypeptidase A & B
Elastase |
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Term
| Additional digestion to amino acids in the cytoplasm is done by |
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Definition
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Term
| Only _____ can get out of the enterocytes and into the blood, where they head to the liver for processing. |
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Definition
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Term
| Where is most water absorbed? |
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Definition
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Term
| What is "colonic salvage?" |
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Definition
Na reabsorption in the colon
Some water reabsorbed with it. |
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Term
| In the jejunum, Na+ is absorbed by |
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Definition
| the Na+/H+ exchange pump, which puts H+ in the lumen. |
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Term
| Describe chloride absorption in the duodenum and jejunum. |
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Definition
| Passive diffusion following Na+ into the cells. |
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Term
| Describe the Cl/bicarb exchanger in the ileum and colon. |
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Definition
Cl in, bicarb out
neutralizes the H+ from bacteria |
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Term
| How is bicarb "absorbed" into the jejunum? |
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Definition
| As CO2 from all the H+ (from Na/H exchanger) reacting with bicarb in the lumen. |
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Term
| How is K passively absorbed in the jejunum and ileum? |
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Definition
| If the lumen concentration is higher than cellular. As water is absorbed into the cell, the lumen concentration gradient increases and more K is absorbed. |
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Term
| How can diarrhea reduce K absorption? |
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Definition
| the rapid flow disperces the concentration gradient -> can contribute to metabolic acidosis |
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Term
| Low pH favors the _____ form of iron, which is easier to absorb. Absorption happens in the _____. |
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Definition
| ferrous (Fe2+), duodenum/jejunum |
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Term
| Iron needs a carrier protein to get inside the enterocyte. |
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Definition
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Term
| Bile salts _____ Ca absorption. |
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Definition
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Term
| The major site of Ca absorption regulation is the _____. It responds to changes in plasma Ca concentrations. |
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Definition
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Term
| Calcium enters the enterocyte bound to _____. |
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Definition
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Term
| Magnesium absorption is through _____. The rate is enhanced by _____. |
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Definition
| passive diffusion ; acidic environment |
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Term
| Phosphate is absorbed by the _____. |
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Definition
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Term
| Fat soluble vitamins are absorbed by |
|
Definition
| incorporation into micelles and diffusion into enterocytes |
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Term
| Water soluble vitamins are absorbed by |
|
Definition
| secondary active transport with sodium |
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Term
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Definition
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Term
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Definition
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Term
| B12 needs ____ for protection from pepsin. |
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Definition
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Term
| B12 needs _____ to facilitate absorption. |
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Definition
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Term
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Definition
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Term
| The B12/IF complex is absorbed in the |
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Definition
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Term
| B12/IF complex does this before binding to a receptor in the terminal ileum. |
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Definition
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Definition
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Definition
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