Lipolysis, Fatty Acid Oxidation and Ketogenesis Flashcards

1
Q

What is lipolysis? and what are lipase?

A

Fatty acids are mobilized from adipose tissue via activation of lipase through process called lipolysis.

They break the ester bonds of triglyceride (using water) to release fatty acids and glycerol.

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2
Q

What are the lipase within the adipocyte? What do they do?

A
  1. Adipose triglyceride lipase (ATGL), hormone sensitive lipase (HSL) and monoglyceride lipase (MGL) = adipose TG to FA

ATGL and HSL are highly regulated

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3
Q

What does Lipoprotein lipase do and where is it located? What about Pancreatic lipase?

A

LPL= Circulating TG to FA (in VLDL & Chylomicrons). LDL is located extracellularly on the capillary endothelium of adipose tissue.

Pancreatic Lipase= ingested TG to FA (and DG & MG)

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4
Q

What is Perlipin?

A

It is a protein surrounding the lipid droplet that positions and activates HSL & ATGL!

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5
Q

What are Free Fatty Acids (FFA) or Non-esterified fatty acids (NEFA)?

A

They are fatty acids that are circulating in plasma and bound to albumin.

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6
Q

What does CD36 do?

A

Converts Fatty Acid + ATP –> Fatty Acid Acyl-Coa

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7
Q

Can fatty acyl-CoA enter the mitochondria? When can it enter?

A

It cannot enter until it is converted to fatty acyl-carnitine by carnitine acyltransferase I

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8
Q

What inhibits CAT-I (carnitine acyltransferase I)?

A

Malonyl-CoA (generated by ACC).

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9
Q

What happens when glucose is readily available and glycolytic rates are high?

A

Malonyl-CoA will be abundant and fatty acids will not be oxidized!

When glucose is unavailable, malignly CoA levels will fall and fatty acid oxidation will increase!

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10
Q

What are ketone bodies useful for?

A

Can be utilized by muscle (heart and skeletal), and also can be made available to brain (which fatty acids are not, since FA cannot cross blood-brain barrier).

Ketogenesis only occurs in the LIVER!!!

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11
Q

What happens when OAA is low?

A

This means that glucose is relatively unavailable… So conversion of acetyl CoA to citrate is low and now you need to convert Acetyl CoA to acetoacetate and B-hydroxybutyrate

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12
Q

What do you need Monocarboxylate transporter (MCT1)?

A

Transports ketones and is used during ketone oxidation

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13
Q

What happens when you have an accumulation of ketones or a mutation in MCT1?

A

Can have metabolic acidosis (ketoacidosis)

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14
Q

Can glucose be synthesized from fatty acids?

A

NO!!!

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