Green - Digestion Of Lipids Flashcards Preview

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Flashcards in Green - Digestion Of Lipids Deck (38)
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1
Q

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

A

Abetalipopproteinemia

2
Q

Non-enzymatic protein required for digestion of triglycerides

A

Colipase

3
Q

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

A

Inflammatory/infectious diarrhea

4
Q

Major mechanism for re-esterifying digested triglycerides in enterocytes

A

Monoglyceride acylation pathway

5
Q

Diarrhea caused by the presence of unabsorbable solutes in the intestines

A

Osmotic diarrhea

6
Q

Secondary mechanism for re-esterifying digested triglycerides in enterocytes

A

Phosphatidic acid pathway

7
Q

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

A

Secretory diarrhea

8
Q

Fat in feces

A

Steatorrhea

9
Q

Gastric lipase hydrolyzes triglycerides to ?

A

Diglycerides and free fatty acids

10
Q

Explain the process of lipid digestion in the stomach

A

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

11
Q

Complete emulsification of fats requires what pH?

A

Neutral or slightly alkaline

12
Q

Pancreatic enzymes hydrolyze lipids to : (x4)

A

Fatty acids

Monoglycerides

Lysophospholipids

Cholesterol

13
Q

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

A

Pancreatic lipase

Cholesterol ester hydrolase

Phospholipase A2

14
Q

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

A

Pancreatic lipase

15
Q

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

A

Cholesterol ester hydrolase

16
Q

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

A

Phospholipase A2

17
Q

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

A

Colipase

18
Q

Chylomicrons are transported out of enterocyte via?

A

Exocytosis

19
Q

Where do chylomicrons enter when they leave the enterocytes/

A

Lacteals

Thru gaps between endothelial cells lining lymphatics

20
Q

What makes up a chylomicron?

A

Core; triglycerides, esterified cholesterol, fat soluble vitamins

Surface; phospholipids, apoprotein, free cholesterol

21
Q

Chylomicrons reach the blood stream via ________

A

Thoracic duct

22
Q

Excretion of more than 7g fat/day in feces

A

Lipid malabsorption

23
Q

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

A

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

Occurs in pancreatitis, pancreatic carcinoma, and cystic fibrosis

24
Q

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

A

Hepatic failure

Cholelithiasis

Bacteria or acids cause bile salts to not work

25
Q

What are 4 ways that you can get lipid malabsorption?

A

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

26
Q

Explain gluten sprue/gluten enteropathy

A

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

27
Q

_______ cells use Na-Cl cotransport mechanism to bring Cl- into cell against Cl- gradient

Na-K ATPase keeps intracellular [Na] low

A

Crypt cells

28
Q

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

A

2Cl- Na K+ cotransporter

29
Q

What does intestinal secretion of water do?

A

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

30
Q

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

A

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.

31
Q

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

A

Ca++ CAMP

This is for water movement into lumen ))

32
Q

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

A

Diarrhea

33
Q

What is the pathophysiology of osmotic diarrhea?

A

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

34
Q

Explain what happens in secretory diarrhea

A

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

35
Q

Causes of secretory diarrhea?

A

Infection of intestine by bacteria

Certain tumors

36
Q

How does oral rehydration therapy work?

A

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

37
Q

What are the roles of colonic flora? (X4)

A

Digest carbohydrates

Make secondary bile acids

Generate short chain fatty acids

Limit invasion of pathogenic microorganisms

38
Q

3 sources of intestinal gas are?

A

Swallowed air

Gas diffusion from bloodstream

Gas created by bacterial action in ileum and colon