Lecture 32 - Coordinating Metabolism: Fuel Storage Flashcards
Why do we need fuel stores?
Because we can’t store ATP or transfer it to other tissues, it must be made in the cell requiring it at the time by oxidizing fuels
What is glucose stored as?
glycogen in liver and muscle
What are fatty acids stored as?
triacylglycerol droplets in adipose
Is there a protein store?
No
When may stored energy be required
between meals, overnight, for activity i.e. exercise
What is required to maintain glucose levels?
Fuel stores
How do we survive prolonged fasting or starvation?
With fuel stores
What is the energy equivalent in 15kg of TAG?
590000kJ
What can the liver NOT use for fuel?
Ketones
What fuels can muscles use?
All fuels
What can’t the brain use for fuel?
Fatty acids
Why can’t the brain use fatty acids?
They can’t cross the blood brain barrier (BBB)
What can’t RBCs use for fuel?
Fatty acids
Why can’t RBCs use fatty acids?
Because they don’t have mitochondria
What is adipose specialised in?
Storing and mobilising fats
Is there a limit on the amount of fat you store?
No unlimited
What are excess TAGs and glucose from diet converted to?
stored fat
What is TAG synthesis in adipocytes driven by?
Insulin
What things does insulin do to a adipocyte?
- Promotes glucose uptake via GLUT4
- Stimulates LPL
- Stimulates glycolysis via hexokinase
- Stimulates DNL
What does glucose provide to an adipocyte?
Glycerol-phosphate backbone, and provides acetyl-CoA for de novo lipogenesis (DNL)
What allows glucose uptake by adipose?
GLUT4
What allows glucose uptake by Liver?
GLUT2
Is GLUT 2 stimulated by insulin?
No
Is GLUT 4 stimulated by insulin?
Yes
What is dietary fat packaged into?
Chylomicrons
What is glucose metabolised to in adipocytes?
Glycerol-3-Phosphate, and then used as the backbone for TAG synthesis
What does stimulation of lipoprotein lipase (LPL) by insulin do?
hydrolyses TAGs to release FA into tissues where they are resynthesized into TAGs