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Fundamentals of Nutrition > Transport of lipids and metabolism in tissues > Flashcards

Transport of lipids and metabolism in tissues Flashcards

1
Q

when does blood lipid level peak?

A

30 minutes to 3 hours following a meal

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2
Q

when does blood lipid level return to normal?

A

after 5-6 hours

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3
Q

where does hydrolysis of chylomicrons take place?

A

in the endothelial cell surface of small blood vessels

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4
Q

what are the types of lipoproteins?

A

chylomicrons, LDL, VLDL and HDL

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5
Q

what are some structural parts of the plasma lipoprotein?

A
  1. Phospholipid monolayer
  2. triacylglycerol and cholesteryl ester in the center
  3. apoproteins (integral or peripheral)
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6
Q

lipoproteins differ according to ________.

A
  • lipid:protein ratio
  • type of lipid
  • proportion of lipid
  • density
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7
Q

what are apolipoproteins? and what are there functions?

A

they are protein components of lipoproteins (apoproteins on the surface)

functions:
- stabilize lipoprotein during circulation
- provide specificity for lipoproteins (recognition by receptors)
- stimulate enzymatic reactions which regulate metabolic functions of lipoproteins

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8
Q

what are some examples of apolipoprotein?

A

apoB-100 (LDL) or apoA-1 (HDL)

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9
Q

which lipoprotein has the highest percentage of tiacylglycerol?

A

Chylomicrons

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10
Q

which lipoprotein has the highest percentage of protein?

A

HDL

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11
Q

what happens to the chylomicron remnants inside the liver?

A

broken down by Lysozymes and recycled

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12
Q

what are the two lipoprotein transport systems?

A
  1. exogenous (from diet)

2. endogenous (from blood)

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13
Q

what happens in the Exogenous system?

A
  1. chylomicrons enter the blood circulation from the lymphatic system
  2. Apo E and Apo C are transferred to chylomicrons from HDL particles in the blood stream
  3. Apo C enhances interactions of chylomicrons with lipoprotein lipase (LPL)
  4. triglycerides withing chylomicrons are hydrolyzed into free fatty acids which are stored by adipose tissue or used for energy in muscles
  5. chylomicron remnants are removed by the liver mediated by apo E
  6. cholesterol in the liver is incorporated into bile acids, which are exported to the intestine
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14
Q

what are some chylomicron remnants?

A

cholesterol, amino acids, etc

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15
Q

What are the parts of the Endogenous system?

A
  1. liver packages cholesterol and triglycerides into VLDL particles accompanied by apo B-100 and phospholipid
  2. VLDL is catabolized by LPL releasing fatty acids to muscle and adipose tissue
  3. half of the VLDL remnants (IDL) enter the liver by hepatic recpetors that recognize apo E to be hydrolyzed
  4. the remaining IDL is catabolized further by LPL and hepatic lipase which removes aditional triglyceride, apo E and apo C forming LDL particles
  5. LDL hydrolysis occurs via LDL receptor mediated endocytosis in the liver and peripheral cells, directed by LDL’s apo B-100 and apoE
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16
Q

what does system 1 of endogenous transport involve?

A

VLDL, IDL and LDL

17
Q

what is VLDL hydrolyzed to? what enzyme is involved and what are the products?

A

VLDL will be hydrolyzed by LPL to release fatty acids

18
Q

which are the main cholesterol carrying lipoproteins?

A

LDLs

19
Q

what is the main function of LDL ?

A

to transport of cholesterol to tissues with LDL recpetors

20
Q

What do HDL particles do?

A

they remove cholesterol from cholesterol-laden cells (peripheral tissues) and return cholesterol to the liver

21
Q

What is the role of the liver in lipid metabolism?

A
  • bile acid secretion
  • synthesis of lipoprotein (lipid transport)
  • de novo lipid synthesis from non lipid precursors (glucose & amino acids)
  • packaging of synthesized lipids into HDL & VLDL
  • uptake and hydrolysis of chylomicron remnants
22
Q

how does insulin stimulate lipogenesis?

A

by promoting glucose into the cell and by inhibiting the lipase which hydrolyzes the stored triacylglycerides to fatty acids and glycerol

23
Q

In the fed state there is _____ lipogenesis.

A

MORE

24
Q

Insulin _______ glucose uptake and _______ availability and uptake of fatty acids by stimulating ________

A

increases, increases, LPL

25
Q

what does insulin inhibit?

A

intracellular lipase

26
Q

Are adipocytes (adipose tissue) able to synthesize endogenous lipoproteins and uptake of chylomicron remnants?

A

NOPE –> the liver

27
Q

What happens in the fasting state (hypoglycemia)?

A
  • insulin concentration is reduced
  • lypolysis in the adipose tissue increases, therefore more free fatty acids and glycerol
  • fatty acids are oxidized in liver and muscles via acetyl coA
  • some fatty acids are converted to ketone bodies in the liver (for energy)

Fundamentals of Nutrition (14 decks)

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