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Nutr 4210 > 6+7. integrative metabolism lipids > Flashcards

6+7. integrative metabolism lipids Flashcards

1
Q

fat utilization during type of exercise

A
  • decrease with intensity

- increase with duration

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2
Q

fat form in adipose and muscle

A

triacylglycerol (TAG)

triglyceride (TG)

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3
Q

blood fat in what forms

- where from

A
  • albumin-free fatty acids (FFA or FA - from adipose)
  • chylomicrons (intestinal derived)
  • VLDL (liver)
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4
Q

advantages of fat as fuel

A
  • more energy/gram
  • more storage (~120h of marathon running)
  • dont need to consume before or after
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5
Q

disadvantages of fat as fuel

A
  • ~65VO2 max is max intensity sustained fat exclusively
  • fatty acids must be bound
  • cant be used anaerobically
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6
Q

potential limiting factors for fatty acid use

A
  1. mobilization FFA from adipose
  2. FFA uptake by muscle (transport across sarcolemma)
  3. mitochondrial membrane transport
  4. fat oxidation
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7
Q

role of insulin in fat metabolism

A

inhibits hormone sensitive lipase (HSL)

result

  • reduces intracellular lipolysis of TG
  • promotes TAG storage in adipocyte
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8
Q

role of EPI in FFA mobilization

A

binds membrane receptor (adenylate cyclase)

  • cAMP produced
  • activates (phosphorylates protein kinase A
  • moves “perilipin” coating on lipid droplet
  • allows hormone sensitive lipase (HSL) to bind
  • TAG converted to FFAs
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9
Q

perilipins

A

proteins coating on lipid droplets that prevents HSL from binding
- removed by phosphorylated protein kinase A

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10
Q

affects of exercise on adipose tissue lipolysis

A

increased HSL amount and sensitivity to stim by EPI (5 or 20 min)
- levels vary depending on fat deposit

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11
Q

FFA release from adipose tissue during high intensity

- rate limiting step?

A

impaired

  • reduced blood flow to adipose tissue
  • not enough albumin reaches adipocyte for transport
  • FAs must be bound in blood
  • limiting step
  • infused FA into blood improves fat oxidation at high intensities
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12
Q

FFA uptake into skeletal muscle and usage

A

FFA freely crosses membrane into cytosol

  • converted to “fatty acyl CoA”
  • crosses into mitochondria
  • beta oxidation
  • acetyl CoA
  • citric acid cycle
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13
Q

exercise and lipoprotein lipase (LPL) concentration in skeletal muscle

A

increased
- higher post 8h
- even higher post 22h
ensures increased flux of fatty acids to contracting muscle

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14
Q

FA sacrolemmal transporters in muscle

A

FAT/CD36

  • fatty acid translocase
  • most important **

FABPpm

  • fatty acid binding protein (plasma membrane)
  • peripheral protein
  • doesnt span the membrane

FATP1-6
- family of fatty acid transporters

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15
Q

ACS1

A

plasma membrane acyl-CoA synthetase

- FA to acyl-CoA

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16
Q

how FA enters muscle

- 5 ways

A
  1. FA into cell simple diffusion
  2. CD36 alone / with FABPpm increase local conc, and increase diffusion
  3. CD36 active transport, binds FAs to FABPc before entering pathways
  4. some transported by FA transport proteins, rapidly activated by acyl-CoA synthatse –> aceyl CoA esters
  5. very long chain FAs transported by FATPs, converted to VLC-acyl-CoA
17
Q

how FA receptors stimulated to move to plasma membrane

A

same as glucose
- glut4 and FAT/CD36

insulin
- PI3-k pathway
muscle contraction
- AMPK pathway

*additive effect

18
Q

FA entry into mitochondria

A
  • FA activated by acyl CoA synthetase
  • FA acyl CoA
  • Carnitine pamitoyl transferase 1 (CPT1)
  • fatty acyl carnitine
    now can cross into mitochondria
  • CPT1 rate limiting step
  • found FAT/CD36 on mitochondria membrane (significance still unclear)
19
Q

AMPK regulation of fat metabolism

A

activates

  • malonyl CoA decarboxylase (MCD)
  • malonyl CoA –> acetyl CoA

inactivates

  • acetyl-CoA carboxylase (ACC)
  • acetyl CoA –/–> malonyl CoA

*malonyl CoA inhibits CPT1
AMPK decrease malonyl CoA –> increases CPT1 –> increase FA oxidation

20
Q

enzymes increased in concentration with training to improve FA oxidation

A

beta hydroxyacyl dehydrogenase (betaHAD)
- beta oxidation

citrate synthase (CS)
- krebs cycle

cytochrome oxidase
- etc cycle

CPT1
- makes fatty acyl carnitine in cytosol

  • classical markers for training status
21
Q

what happens to plasma FFA with aerobic training

A

return to baseline levels quicker

  • lower levels in blood
  • more dependency on intramuscular TGs
  • more FA transporters (FAT/CD36***)
22
Q

high IMTG seen in obese, why also seen in trained

A

skeletal muscle remains insulin sensitive

Nutr 4210 (16 decks)

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