Green - Digestion Of Lipids

Question 1

Rare inherited disorder in which a person does not make beta-lipoproteins and thus cannot absorb dietary fats, cholesterol, and fat-soluble vitamins

Answer 1

Abetalipopproteinemia

Question 2

Non-enzymatic protein required for digestion of triglycerides

Answer 2

Colipase

Question 3

Diarrhea caused by infection w/ bacteria or viruses that leads to loss of enterocytes

Answer 3

Inflammatory/infectious diarrhea

Question 4

Major mechanism for re-esterifying digested triglycerides in enterocytes

Answer 4

Monoglyceride acylation pathway

Question 5

Diarrhea caused by the presence of unabsorbable solutes in the intestines

Answer 5

Osmotic diarrhea

Question 6

Secondary mechanism for re-esterifying digested triglycerides in enterocytes

Answer 6

Phosphatidic acid pathway

Question 7

Diarrhea caused by infection w/ bacteria which secrete toxins that increase secretion by intestinal cells

Answer 7

Secretory diarrhea

Question 8

Fat in feces

Answer 8

Steatorrhea

Question 9

Gastric lipase hydrolyzes triglycerides to ?

Answer 9

Diglycerides and free fatty acids

Question 10

Explain the process of lipid digestion in the stomach

Answer 10

The stomach mixing breaks lipids into droplets to increase surface area

Low pH inhibits complete emulsification

Gastric lipase breaks triglycerides to diglycerides and free fatty acids

CCK slows gastric emptying to allow time for digestion in duodenum

Question 11

Complete emulsification of fats requires what pH?

Answer 11

Neutral or slightly alkaline

Question 12

Pancreatic enzymes hydrolyze lipids to : (x4)

Answer 12

Fatty acids

Monoglycerides

Lysophospholipids

Cholesterol

Question 13

What are 3 pancreatic enzymes involved in the hydrolysis of lipids in the small intestine?

Answer 13

Pancreatic lipase

Cholesterol ester hydrolase

Phospholipase A2

Question 14

Cleaves fatty acid from position 1 and 3, leaving 2 fatty acids and 2-monoglyceride

Answer 14

Pancreatic lipase

Question 15

Cleaves fatty acid from cholesterol esters, leaving free cholesterol and fatty acid

Answer 15

Cholesterol ester hydrolase

Question 16

Releases fatty acid from position 2 of phospholipids, yielding lysophospholipids and free fatty acid

Answer 16

Phospholipase A2

Question 17

Non-enzymatic protein secreted as inactive form by pancreas

Prevents inhibition of pancreatic lipase by bile salts

Acts as an anchor for lipase binding enzyme to bile salts of surface of droplet of emulsifieed triglyceride

1:1 ratio w/ lipase

Also binds bile salt micelle, keeping it close ot site of hydrolysis

Answer 17

Colipase

Question 18

Chylomicrons are transported out of enterocyte via?

Answer 18

Exocytosis

Question 19

Where do chylomicrons enter when they leave the enterocytes/

Answer 19

Lacteals

Thru gaps between endothelial cells lining lymphatics

Question 20

What makes up a chylomicron?

Answer 20

Core; triglycerides, esterified cholesterol, fat soluble vitamins

Surface; phospholipids, apoprotein, free cholesterol

Question 21

Chylomicrons reach the blood stream via ________

Answer 21

Thoracic duct

Question 22

Excretion of more than 7g fat/day in feces

Answer 22

Lipid malabsorption

Question 23

What happens when you have lipid malabsorption due to the inability to digest fats?

Answer 23

The pancreatic enzymes are either not secreted or inactivated due to low pH

Occurs in pancreatitis, pancreatic carcinoma, and cystic fibrosis

Question 24

What can cause malabsorption due to the absence of bile salts?

Answer 24

Hepatic failure

Cholelithiasis

Bacteria or acids cause bile salts to not work

Question 25

What are 4 ways that you can get lipid malabsorption?

Answer 25

Absence of bile salts Failure to digest fat (lack of pancreatic enzyme) Conditions that affect or decrease the number of absorbing cells Failure to synthesize apoproteins

Question 26

Explain gluten sprue/gluten enteropathy

Answer 26

Pt has allergic rxn to gluten. As a result, loss of villi in small intestine Malabsorption of fats, proteins, and carbohydrates Treat w/ gluten free diet

Question 27

_______ cells use Na-Cl cotransport mechanism to bring Cl- into cell against Cl- gradient Na-K ATPase keeps intracellular [Na] low

Answer 27

Crypt cells

Question 28

What type of cotransporters do crypt cells use to get Cl- inside from the blood? (In order to secrete water)

Answer 28

2Cl- Na K+ cotransporter

Question 29

What does intestinal secretion of water do?

Answer 29

It assists in processes of digestion and absorption by maintaining liquidity of the cyme in small intestine

Question 30

Explain the process of H2O secretion in the small intestine (to keep chyme liquidity up for digestion and absorption)

Answer 30

Crypt cells have 2Cl Na K cotransporters on their basolateral membranes to bring Cl into cell. Then, there are Cl channels on the apical membrane which are stimulated by GI hormones and neurotransmitters. Cl- enters lumen. Na+ follows. Water follows to maintain isotonicity.

Question 31

The Cl- channels in the apical membrane are activated by increase in _________ or _____ levels

Answer 31

Ca++ CAMP | This is for water movement into lumen ))

Question 32

Defined as excretion of 200g or more of H2O in stools of adult during 24 hour period

Answer 32

Diarrhea

Question 33

What is the pathophysiology of osmotic diarrhea?

Answer 33

There’s an accumulation of nonreabsorbable substances in the small intestine. This causes an osmotic imbalance, so water follows. There is then too much water to be reabsorbed in the large intestine

Question 34

Explain what happens in secretory diarrhea

Answer 34

Caused by infection by certain bacteria (V. Cholerae or E. Coli) or some tumors. The Cl- channels in the small intestine are activated. Cl- enters lumen Na and H2O follow (can lose liters of water and salt per day) Na absorption w/ Cl- is inhibited but w/ glucose is intact

Question 35

Causes of secretory diarrhea?

Answer 35

Infection of intestine by bacteria Certain tumors

Question 36

How does oral rehydration therapy work?

Answer 36

Patient’s with secretory diarrhea’s Na-Glucose cotransporters still work. So give them water w/ salt and glucose in it and you can improve the Na gradient so that water will be absorbed

Question 37

What are the roles of colonic flora? (X4)

Answer 37

Digest carbohydrates Make secondary bile acids Generate short chain fatty acids Limit invasion of pathogenic microorganisms

Question 38

3 sources of intestinal gas are?

Answer 38

Swallowed air Gas diffusion from bloodstream Gas created by bacterial action in ileum and colon