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GI- Week 3 > Skildum: Lipids > Flashcards

Skildum: Lipids Flashcards

1
Q

Which is the most calorically dense food?

A

Fat

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2
Q

Which particle functions to promote cholesterol homeostasis?

A

High density lipoprotein (reverse cholesterol transports from tissue to the liver–helps maintain circulating cholesterol levels)

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3
Q

Which lipoprotein activates an extracellular lipase in capillary beds?

A

ApoCII

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4
Q

What are the important metabolic fates of Fatty acids?

A
  1. Oxidized to CO2 and H20
  2. Triacylglycerol (adipose tissue stores)
  3. Phospholipids and sphingolipids (membranes)
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5
Q

What forms arachidonic acid (EPA)?

A

w6fatty acids (linoleic, linolenic acid)

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6
Q

What can arachidonic acid be turned into?

A

Leukotrienes
PGs
Thromboxanes

*can cause a basal contraction of the LES

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7
Q

What do bile salts do?

A

TAG enters mouth>
mechanical breakdown>
TAG enters SI>
gall bladder secretes bile salts which act as detergents (derived from cholesterol and synthesized in the liver then stored in the GB)>
makes cholesterol more accessible to the solvents

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8
Q

What does the pancreas do?

A

Secretes pancreatic lipase>
hydrolyzes two of the FA ester bonds form TAG and makes 2 free FA and 2 MG>
these substances are taken into an enterocyte>
repackaged into TAG>
packaged w/ lipoproteins into a chilomicron then released into the blood stream

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9
Q

What does the bolus of food passing into the stomach do?

A

Causes secretion of:

secretin> pancreas> pancreatic lipase

cholecystokinin> gall bladder> bile salts

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10
Q

What are the three forms that fat in the diet is consumed as?

A

triacyglyerol
phospholipids
cholesterol esters

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11
Q

Where does the pancreatic lipase cut triacylglycerol?

A

At the number 1 and 3 position

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12
Q

Triacylglycerol + pancreatic lipase forms what?

A

2 fatty acids +

2 monoacylglycerol

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13
Q

What does PLA-2 produced by the pancreas do?

A

Cuts the number 2 fatty acid from triacyglycerol (not required for digestion)

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14
Q

How is fat metabolized?

A 
TG>
digested by bile salts>
TG in micelles>
pancreatic lipase>
2 FA + 2 monoacylglycerol>
uptake by gut epithelial cells>
TG in chylomicrons>
lymphatic transport>
chylomicrons in blood
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15
Q

What happens to short and medium chain Fatty acids?

A

By pass chylomicron stage and are taken up by gut epithelial cells and then enter the portal blood

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16
Q

Fat that is consumed as a cholesterol ester is broken down by cholesterol esterase to…

A

Fatty acid and cholesterol (both can be taken up by gut epithelial cells and packaged as lipoproteins)

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17
Q

Fat that is consumed as phospholipids is broken down by PLA2 (cuts number 2 position) to form…

A

FA and lysophospholipid (taken up by gut epithelial cell and packaged into lipoprotein particle)

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18
Q

The polar head groups of phospholipids can be…

A

choline
ethanolamine
inositol

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19
Q

How does fat digestion take a different route than normal digestion?

A

it bypasses the liver and enters the lymphatic system–> blood–> peripheral tissue–> liver

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20
Q

What happens in intestinal epithelial cells?

A

FA are re-esterified to glycerol to make TG in intestinal epithelial cells

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21
Q

What is the major apoprotein of chylomicrons?

A

apoB-48–seed crystal to form chylomicron particle

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22
Q

What is ApoB48 encoded by?

A

same gene as apoB100, the apoprotein of VLDL

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23
Q

How is a nascent chylomicron formed?

A

TG are absorbed by brush border villae in the intestinal lumen and stored in teh SER. The RER makes ApoB-48. These two products fuse at the golgi complex and form nascent chylomicrons, which then enter the lymph.

24
Q

What is the hallmark of a chylomicron?

A

apoB-48–> if a protein contains apo B 48 that particle contains dietary fat

25
Q

What is the hallmark of a VLDL particle?

A

apoB-100 (from the liver)

26
Q

ApoB-48 and ApoB-100 are produced by the same B-apoprotein gene. How RNA editing produce two different products?

A

intestine> stop codon> apoB48

liver–> C–> unedited full length transcript in hepatocytes

27
Q

What happens once chylomicrons enter the blood?

A

They receive ApoCII and ApoE from HDL

28
Q

What is the function of HDL?

A

Maintain cholesterol and apoprotein homeostasis

29
Q

What converts a nascent chylomicron to a mature chylomicron?

A

ApoCII from HDL

30
Q

What is the function of ApoCII?

A

Activates LPL in peripheral tissue (capillary beds of muscle and adipose tissue) which allows the chylomicrons to deliver calories to the peripheral tissue

31
Q

What happens when the chylomicron interacts w/ the LPL?

A

Chylomicron/CII interacts w/ LPL>
cuts off free FA from TG>
Free FA are then oxidized for generation of ATP into CO2 and H20 (if work is being done) >
or FA can be re-esterified to glycerol and stored as TG in adipose tissue (no work being done)

32
Q

What happens when the chylomicron loses CII?

A

It becomes a chylomicron remnant and is recycled by the liver

33
Q

What happens to FA and cholesterol taken up by the liver from chylomicron remnants?

A

They can be repackaged w/ ApoB100 as VLDL

34
Q

What is the function of VLDLs?

A

Deliver fatty acid fuels to tissues of the body (similar to chylomicrons)

35
Q

What activates a nascent VLDL?

A

apoCII

36
Q

What is the diff between chylomicrons and VLDL?

A

chylomicrons are much BIGGER but the relative compositions of each are similar

37
Q

When can adipose store FA as TG (it can be taken up by chylomicrons or VLDL particles)?

A

FED STATE!

The glycerol 3 phosphate backbone can ONLY be produced by glycolysis in adipocytes

38
Q

What is the largest lipoprotein?

A

chylomicron

39
Q

What do chylomicrons do?

A

transfer dietary fat from gut to the tissues

40
Q

What is the source of chylomicrons?

A

intestinal epithelial cells

41
Q

What proteins are associated w/ chylomicrons?

A

48
CII
E

42
Q

What do chylomicron remnants do?

A

return apoproteins to the liver

43
Q

What proteins are associated w/ chylomicron remnants?

A

48
E

(lose CII)

44
Q

What is the function of VLDL?

A

transfer fat produced by dietary carbs to tissues

45
Q

What is the source of VLDL

A

liver

46
Q

What proteins are associated w/ VLDL?

A 
100
C1
CII
CIII
E
47
Q

What is the function of IDL?

A

deliver lipids, cholesterol to tissues

48
Q

What is the source of IDL?

A

remnant of VLDL

49
Q

What proteins are associated w/ IDL?

A 
100
C1
CII
CIII
E

(same as VLDL)

50
Q

What is the function of LDL?

A

Deliver cholesterol to cells

51
Q

What is the source of LDL?

A

remnant of IDL

52
Q

What protein is associated w/ LDL?

A

100

53
Q

What is the fxn of HDL?

A

cholesterol and apoprotein homeostasis

54
Q

What is the source of HDL?

A

liver and intestine

55
Q

What proteins are associated w/ HDL?

A 
A1
A
CI
CII
LCAT

GI- Week 3 (15 decks)

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