Lipid Digestion and Absoprtion Flashcards Preview

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Flashcards in Lipid Digestion and Absoprtion Deck (29):
1

Role of phosphlipids

stabilize the fats which are poorly soluble

2

Saturated FA

no double bonds (completely saturated with hydrogens)

3

Monounsaturated

one double bond

4

Polyunsaturated

two or more double bonds

5

Hydrogenation process

cis double bond + H2 gives rise to a saturated FA (no double bonds)

6

Partial hydrogen process increases ___

trans FA

go from cis double bond --> completely saturated --> collapse of double bond but H forms on opposite side of the other

7

Lipids are readily able to cross the cell membrane but have poor ___ due to ____

solubility due to hydrophobic nature

8

Emulsion

stabilize the fat droplet by adding amphiphatic emulsifying agents--form a surface layer separating main bulk of hydrophobic material from aqueous phase

9

Once emulsified to smaller particles, the fat droplets can be acted on by ____

lipolytic enzymes (soluble proteins)

10

Enzymes present in mouth and stomach that help with absoprtion of fat. How much of a role to they have in adult and neonate stage?

Lingual and gastric lipase --minimal in adult. In neonates, its activity is increased to 30-50% due to immature pancreatic enzymes. Contribute to hydolysis of TG

11

Lipase concerts ____ to _____

triacylglycerols to FFA and diacylglycerol

12

Main digestion of absoprtion of lipids occurs in _____

dudodenum and jejunum

13

Long chain FA induce the 4 following enteroendocrine peptides:

1. Gastrointestinal insulinotropic peptide (GIP)
2. GLP-1 (glucagon like peptide)
3. CCK
4. Secretin

14

Secretin
-stimulus
-release site
-action

-decreased pH
-S cell in dudodenum
-enhances bicarbonate duct secretion by pancrease optimizing pH

15

CCK
-stimulus
-release site
-action (3)

-long chain FA and proteins
-I cells in dudodenum
-acts on following
1. secretion of bile salt by contraction of gall bladder
2. relaxes sphincter of Oddi
3. pancreatic secretion

16

CCK causes pancreatic secretion. List the 4 main enzymes

1. trypsinogen
2. pancreatic lipase and procolipase
3. cholesterol esterase
4. prophospholipase A2

17

Enteropeptidase
-action
-activated by

-converts trypsinogen --> trypsin
-activated by CCK

18

trypsin
-action
-activated by

-makes enzyme (procolipase to colipase, prophospholipase A2 to phospholipase A2)
-activated by enteropeptidase

19

Role of phospholipase A2

phospholipids --> FFA + lysolecithin

20

Cholesterol esterase role

cholesterol ester --> cholesterol

21

Importance of pancreatic colipase for action of pancreatic lipase

pancreatic colipase penetrates the phospholipid coating and attaches to the triacylglyceride. breaks barrier for pancreatic lipase which will attach to colipase, allows lipase to do its thing

22

Without colipase, what would inhibit the activity of pancreatic lipase?

bile salts

23

Role of bile salts

acts as a detergent--surrounds the emulsion making smaller lipid droplets (micelles) with increased SA for lipase digestion

24

Composition of mixed micelle

2 monoclygerols, FFA, cholesterol, and lysolecithin all stabilized by bile acids and coated with phospholipid

25

Critical micelle concentration

the minimal concentration of bile salts required to form a mixed micelle

26

(unconjugated/conjucated) bile acids require a lower concentration to form a critical micelle concentration

conjugated

27

NPCILI and its importance clinically

Neimann Pick C1 Like 1 Protein
-transporter for cholesterol into the small intestine
-once inside intestine, gets converted to chole and FFA
-we have drugs like ezetimibe which will block NPCILI and thus decrease cholesterol absoprtion

28

Statins

causes an increase in LDL receptors to pool cholesterol into the liver

29

4 physiological reasons for malabsoprtion of lipids

1. decrease bile (intra or extra hepatic)
2. enterocytes malfunctioning
3. no pancreas -- not putting out lipase, cant digest fats
4. bacterial overgrowth--Crohns