CHO and Fats

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Flashcards by , created almost 6 years ago

Exercise Metabolism Flashcards on CHO and Fats, created by alexlpeart on 04/30/2013.

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alexlpeart
Created by alexlpeart almost 6 years ago
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Question Answer
Describe what happens to fat oxidation with intensity Increases up to a point (about 75% vo2max) then falls quickly.
What is cross over? Where CHO and fat metabolism are equal so each system is contributing to energy production the same.
What do we see increasing CHO metabolism as exercise intensity increases? Elevated calcium, AMP and adrenaline activate glycogen phosphorylase (converting glucose attached to glycogen into glucose-1-phosphate) and also activating AMPK which increases GLUT4 translocation by converting Rab GDP into Rab GTP.
Give reasons why fat oxidation initially increases as we increase exercise intensity. Adrenaline in the blood activated adenylate cyclase which activated cAMP which activates PK to PKA meaning HSL becomes phosphorylated and therefore active. this means more TG are broken down and in the blood for use. Also we see greater uptake of fat uptake into the cell as AMPK increases FAT/CD36 activity moving fat into the cell. There is also elevated fat uptake into the mitochondria as AMPK inhibits the malynol-CoA production allowing CTP1 to take fats into the mitochondria.
Give some metabolic reasons why at high intensity exercise we see a decrease in fat oxidation for energy production. Higher intensity leads to increased acetyl CoA which means more carnitine is converted to acetyl-carnitine so less carnitine transport into the mitochondria. Also decrease in pH causes a decrease in CTP1 activity.
Suggest why fatty acid levels decrease during high intensity exercise. Reduced blood flow to the adipose tissue as working muscles favored.
Describe the action of heparin on LPL It causes LPLs to breakdown more triglycerides (VLDL) meaning there are more FA and glycerol in the blood.
How does the transport of long chain and medium chain fatty acids into the mitochondria differ? long chain require CTP1 to transport them across the mitochondria while medium chain don't.
Describe how increasing insulin levels affects CTP1. Increased insulin occurs due to increased plasma glucose, which means glycolysis will be higher,so acetyl CoA will be higher, so malonyl-CoA will be higher so CTP1 is inhibited.
Describe the mechanism for AMPK increasing CTP1 activity. AMPK inhibits the action of ACC so less acetyl-CoA is converted to malonyl-CoA so less inhibition of CTP1. AMPK also activated an enzyme which turns malonyl-CoA into acetyl-CoA called malonyl-CoA decarboxylase (MCD).