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Year 1 > Lipid Digestion and Absoprtion > Flashcards

Lipid Digestion and Absoprtion Flashcards

1
Q

Role of phosphlipids

A

stabilize the fats which are poorly soluble

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2
Q

Saturated FA

A

no double bonds (completely saturated with hydrogens)

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3
Q

Monounsaturated

A

one double bond

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4
Q

Polyunsaturated

A

two or more double bonds

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5
Q

Hydrogenation process

A

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

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6
Q

Partial hydrogen process increases ___

A

trans FA

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

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7
Q

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

A

solubility due to hydrophobic nature

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8
Q

Emulsion

A

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

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9
Q

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

A

lipolytic enzymes (soluble proteins)

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10
Q

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?

A

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

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11
Q

Lipase concerts ____ to _____

A

triacylglycerols to FFA and diacylglycerol

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12
Q

Main digestion of absoprtion of lipids occurs in _____

A

dudodenum and jejunum

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13
Q

Long chain FA induce the 4 following enteroendocrine peptides:

A
  1. Gastrointestinal insulinotropic peptide (GIP)
  2. GLP-1 (glucagon like peptide)
  3. CCK
  4. Secretin
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14
Q

Secretin

  • stimulus
  • release site
  • action
A
  • decreased pH
  • S cell in dudodenum
  • enhances bicarbonate duct secretion by pancrease optimizing pH
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15
Q

CCK

  • stimulus
  • release site
  • action (3)
A
  • 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
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16
Q

CCK causes pancreatic secretion. List the 4 main enzymes

A
  1. trypsinogen
  2. pancreatic lipase and procolipase
  3. cholesterol esterase
  4. prophospholipase A2
17
Q

Enteropeptidase

  • action
  • activated by
A
  • converts trypsinogen –> trypsin

- activated by CCK

18
Q

trypsin

  • action
  • activated by
A
  • makes enzyme (procolipase to colipase, prophospholipase A2 to phospholipase A2)
  • activated by enteropeptidase
19
Q

Role of phospholipase A2

A

phospholipids –> FFA + lysolecithin

20
Q

Cholesterol esterase role

A

cholesterol ester –> cholesterol

21
Q

Importance of pancreatic colipase for action of pancreatic lipase

A

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
Q

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

A

bile salts

23
Q

Role of bile salts

A

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

24
Q

Composition of mixed micelle

A

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

25
Q

Critical micelle concentration

A

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

26
Q

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

A

conjugated

27
Q

NPCILI and its importance clinically

A

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
Q

Statins

A

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

29
Q

4 physiological reasons for malabsoprtion of lipids

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

Year 1 (48 decks)

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