Gi #25: Absorption Malabsorption Diarrhea

Front 1

Which statement about water movement in the bowel is true?

A. Water is actively pumped into and out of the lumen via membrane based H2O pumps
B. Water follows solute
C. Only a small fraction of water in the lumen is reabsorbed
D. Sodium follows water movement

Back 1

B. Water follows solute

(this is why we can use ORT to help with diarrhea. The increased conc. of glucose will cause glucose intake and Na+ intake simultaneously, and water will follow).

Front 2

Secretion in the intestine occurs via which mechanism?

A. Active sodium pumps moving sodium into the lumen
B. Glucose mediated co-transport of sodium and water into the lumen
C. Agonist sensitive chloride channels
D. Ion pumps are located on the brush border

Back 2

C. Agonist sensitive chloride channels

Activated by GPCR method (increased cAMP) which causes increased Cl- secretion and Na+ follows (so does water)

*remember that Ion pumps are not located on the brush border, they are located in the crypts

Front 3

Digestion and absorption of nutrients requires:

A. Passage of food materials unchanged through the lumen
B. Uniform absorption of nutrients throughout the bowel
C. Simple diffusion of all digested molecules across the brush border
D. Digestion of nutrients to simple molecules in the lumen and on the brush border

Back 3

D. Digestion of nutrients to simple molecules in the lumen and on the brush border

Front 4

The symptoms of lactose intolerance are partly a result of:

A. Excess gas production by colonic bacteria
B. Absorption of glucose and galactose at the brush border
C. Diarrhea as a result of passage of iso-osmotic contents through the bowel lumen
D. Lack of monosaccharide receptors on small intestinal epithelial cells

Back 4

A. Excess production by colonic bacter

(which is why patients get flatus as well as diarrhea). Remember that they have receptors, just not the enzymes to degrade lactose. Also, these contents are hypertonic substances (lactose)

Front 5

Fat absorption relies on:

A. Breakdown of fat molecules on the enterocyte brush border
B. Movement of fat molecules unchanged across enterocytes and into lymphatics
C. Pancreatic enzymes which breakdown triglycerides into chylomicrons
D. Amphipathic molecules which assist in the breakdown and solubilization of fat

Back 5

D. Amphipathic molecules which assist in the breakdown and solubilization of fat

Triglycerides are broken down by pancreatic enzymes into chylomicrons (they are actually broken down into monoglycerides which are then absorbed and converted back into TGs and then packaged as Chylomicrons).