Digestion and Absorption of Lipids/Intestinal Secretions

Question 1

Cholesterol Ester Hydrolase

Answer 1

Cleaves FAs from cholesterol esters resulting in free cholesterol and FA

Question 2

Phospholipase A2

Answer 2

Releases FAs from phospholipids producing lysophospholipid and free FAs

Question 3

Colipase

Answer 3

Non-enzymatic protein secreted by the pancreas that binds to emulsified triglyceride and anchors lipase to bile salts; keeps it close to site of hydrolysis

*Also prevents the bile salts from inhibiting the fnxns of pancreatic lipase

Question 4

Absorption of lipids

Answer 4

Emulsified products are brought to the unstirred water layer on top of the microvilli where bile salts are lost and the lipid-soluble digestion products diffuse into the enterocyte

Question 5

Monoglyceride Acylation Pathway

Answer 5

Triglycerides are synthesized from 2-monoglycerides and CoA-fatty acids

*Occurs in smooth ER

Question 6

Phosphatidic Pathway

Answer 6

2 Acyl CoA + a-glycerophosphate (from hexose metabolism) => Phosphatidic Acid

Phosphatidic Acid + Acy CoA => Triglyceride + PO43-

Question 7

Medium-chain FA absorption

Answer 7

Do not need micelles to cross luminal barrier and do not need resynthesis to enter the bloodstream

Question 8

Chlyomicron Formation

Answer 8

Resynthesized triglycerides and fat-soluble vitamins are in the core; phospholipids and cholesterol are the surface

*Are transported out of cell via exocytosis and enter circulation via lacteals

Question 9

Gluten Enteropathy

Answer 9

“Celiac Sprue”

Allergic reaction to wheat leading to loss of intestinal villi and malabsorption of carbs and protein

Question 10

Abetalipoproteinemia

Answer 10

Failure to synthesize Apoprotein B leading to lack of chylomicron formation

=>Fats, cholesterol, and PVT TIM HALL not absorbed into blood

Question 11

Crypt Cell Secretion

Answer 11

Na+/Cl- co-transport brings Cl- in; CFTR channel takes Cl- out into the lumen

• Na+ follows passively thru paracellular mechanisms as does H2O
• Maintains liquidity of chyme in intestine

Question 12

Osmotic Diarrhea

Answer 12

Excess unabsorbable solute draws water out of intestinal wall

=> diarrhea

Question 13

Secretory Diarrhea

Answer 13

Activation of Cl- channels leads to increased H2O loss
*Na+/glucose absorption is not inhibited; therefore, treatment is Na+/glucose supplements

*Caused by V. cholerae and E. coli

Question 14

Inflammatory Diarrhea

Answer 14

Destruction of intestinal cells by Salmonella, Camplyobacter, or C. difficile

Question 15

Main components of flatus

Answer 15

N2 and sulfur; gas builds up from swallowed air, gas from bacterial metabolism, and diffusion of gas to bloodstream

Question 16

Pancreatic Lipase

Answer 16

Cleaves FAs from 1 and 3 positions resulting in two FAs and 2-monoglyceride

Question 17

Gastric Lipase

Answer 17

Cleaves one bond of triglycerides and mixes them to further break up the fats