Shared Flashcard Set

Details

GI15-16 Digestion and Absorption I and II
Questions and stuff
57
Medical
Graduate
01/25/2012

Additional Medical Flashcards

 


 

Cards

Term
Advantages & disadvantages of cellulose in diet.
Definition

A: regular bowel movements, prevent constipation

D: diarrhea? 

Term
What enzymes are secreted in the mouth?
Definition

Salivary a-amylase -> carbs

lingual lipase -> lipids

Term
What glands/organs secrete enzymes that digest starches? What do they digest them into?
Definition

Salivary glands -> maltose

Pancreas -> maltose

Intestinal mucosa -> Glu, Fru, Gal

Term
What gastric/pancreatic secretions digest protein?
Definition

Stomach: Pepsins -> smaller peptide chains

Pancreas: Trypsin (activated by Ek), Chymotrypsins and Elastase (activated by Trypsin) -> smaller peptide chains

Term
What is the importance of pancreatic trypsin inhibitor?
Definition
Trypsin would injure the pancreas if it was in its active form, therefore it's activated in the SI by enterokinase.
Term
What are the lipases we need to know?
Definition

mouth: lingual lipase

stomach: gastric lipase

small intestine: pancreatic lipase and co-lipase

Term
Release of CCK by the duodenum causes
Definition

gallbladder constriction

spincter of oddi relaxation

pancreatic enzyme release

Term
Pancreatic lipase cleaves TGs into
Definition
FAs and monoglycerides
Term
cholesterol esterase cleaves cholesterol esters into
Definition

cholesterol and acid

 

(also cleaves fat soluble vitamins like D & E)

Term
Phospholipase A2 is activated by trypsin and cleaves phospholipids like lecithin into
Definition

lysolecithin.

 

(this probably isn't exam important)

Term
Co-lipase is activated by
Definition
trypsin
Term
Pancreatic lipase is secreted in its _____ form.
Definition
activated
Term
What's the most important lipase relationship?
Definition
pancreatic lipase and co-lipase!!!
Term
What's important about the SI structure?
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

Term
What's important about the unstirred layer?
Definition
It protects the single cell villous lining from the stuff flowing in the SI lumen.
Term
How is a micelle formed? What are its benefits?
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.

Term
What causes intestinal gas formation?
Definition
unabsorbed carbs that are digested by colon bacteria.
Term
What might happen if you remove the gall bladder?
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.
Term
What would happen if the common bile duct was occluded?
Definition

Backup of bile in the liver.

Jaundice (high blood bilirubin)

Fat in poops

 

Term
What would happen if the pancreatic duct was occluded?
Definition

Pancreatic enzymes wouldn't be released into the duodenum.

Malabsorption

Weird poops

Pancreatitis and probably eventual death.

Term

What does enterokinase do?

Where is it found?

Definition

activates Trypsin

secreted by crypts of lieberkuhn in duodenum

Term
Glu and Gal go through the _____ transporter.
Definition

GLUT2

(Na dependent secondary active transport)

Term
Why does a low sodium diet not affect the Na/K ATPase transporter that the Glu-Na transporter depends on?
Definition
Na is released in all the secretions preceeding the SI anyway.
Term
Fructose uses specific GLUT5 carrier proteins and is imported by
Definition
facilitated diffusion.
Term
What are the brush border saccharidases and their targets and products?
Definition

Maltase -> maltose to glucose

Isomaltase -> isomaltose to glucose

Lactase -> lactose to glu and gal

Sucrase -> sucrose to glu and fru

Term
Dissaccharide deficiency causes...
Definition

malabsorption of carbs

osmotic effects of undigested sugars retains water in the GI lumen

diarrhea

Term
How are di- and tri-peptides absorbe into cell?
Definition
specific peptide transport proteins
Term
Amino acids are absorbed into the cell via
Definition
Na-linked cotransporters
Term
Know these 4 brush border proteases... dumbass.
Definition

Trypsin

Chymotrypin

Carboxypeptidase A & B

Elastase

Term
Additional digestion to amino acids in the cytoplasm is done by
Definition
cytoplasmic proteases
Term
Only _____ can get out of the enterocytes and into the blood, where they head to the liver for processing.
Definition
amino acids
Term
Where is most water absorbed?
Definition
Small intestines
Term
What is "colonic salvage?"
Definition

Na reabsorption in the colon

Some water reabsorbed with it.

Term
In the jejunum, Na+ is absorbed by
Definition
the Na+/H+ exchange pump, which puts H+ in the lumen.
Term
Describe chloride absorption in the duodenum and jejunum.
Definition
Passive diffusion following Na+ into the cells.
Term
Describe the Cl/bicarb exchanger in the ileum and colon.
Definition

Cl in, bicarb out

neutralizes the H+ from bacteria

Term
How is bicarb "absorbed" into the jejunum?
Definition
As CO2 from all the H+ (from Na/H exchanger) reacting with bicarb in the lumen.
Term
How is K passively absorbed in the jejunum and ileum?
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.
Term
How can diarrhea reduce K absorption?
Definition
the rapid flow disperces the concentration gradient  -> can contribute to metabolic acidosis
Term
Low pH favors the _____ form of iron, which is easier to absorb. Absorption happens in the _____.
Definition
ferrous (Fe2+), duodenum/jejunum
Term
Iron needs a carrier protein to get inside the enterocyte.
Definition
DMT1
Term
Bile salts _____ Ca absorption.
Definition
facilitate
Term
The major site of Ca absorption regulation is the _____. It responds to changes in plasma Ca concentrations.
Definition
intestines
Term
Calcium enters the enterocyte bound to _____.
Definition
CaBP
Term
Magnesium absorption is through _____. The rate is enhanced by _____.
Definition
passive diffusion ; acidic environment
Term
Phosphate is absorbed by the _____.
Definition
Na-Pi cotransporter
Term
Fat soluble vitamins are absorbed by
Definition
incorporation into micelles and diffusion into enterocytes
Term
Water soluble vitamins are absorbed by
Definition
secondary active transport with sodium
Term
Pyridoxine absorbed by
Definition
diffusion
Term
Riboflavin absorbed by
Definition
facilitated transport
Term
B12 needs ____ for protection from pepsin.
Definition
R binders
Term
B12 needs _____ to facilitate absorption.
Definition
Intrinsic Factor
Term
Lack of B12 causes
Definition
pernicious anemia
Term
The B12/IF complex is absorbed in the
Definition
terminal ileum
Term
B12/IF complex does this before binding to a receptor in the terminal ileum.
Definition
Dimerize
Term
Plasma B12 is bound to 
Definition
transcobalamin II
Term
Steatorrhea
Definition
fat in stool
Supporting users have an ad free experience!