Fuel storage (L35) Flashcards
Why do we need fuel stores?
Because the body cannot store ATP
What do we use fuel stores for? (3)
- Maintain a supply of glucose between meals
- To provide immediate fuel for increased activity
- For long periods when food intake may be inadequate
How is fat stored?
TAGs stored as fat droplets in adipose tissue
How are TAG’s synthesised?
Glycerol backbone and 3 FA tails
- FA from chylomicrons
- Glycerol backbone from glucose
How are fatty acids activated? (breif)
By being converted into fatty acyl-CoA
How are TAG’s mobilised?
Hydrolysis of TAGS
- Catalysed by hormone sensitive lipase
- Stimulated by: adrenaline and glucagon
- Releases free fatty acids and glycerol
What is glycogen?
Branched polysaccharide with 1,4 and 1,6 glycosidic bonds
Where is glycogen stored?
In liver and muscle
What inputs are needed (other than glucose) for glycogen synthesis?
Requires energy inputs ATP and UTP
What reaction is glycogen synthesis paired with?
G1P to UDP-glucose
What hormones are involved in stimulating the synthesis of fuel stores?
Insulin -> glycogen synthase and branching enzyme
What enzymes break down TAG stores?
adrenaline (stress) and glucagon (fasting) -> stimulate hormone sensitive lipase
What is the involvement of G-protein coupled receptors in the mobilisation of TAGs
Use GTP instead of ATP to activate enzyme
How and where is glucose converted to fatty acids?
complex, energy requiring process that occurs in the liver
What are the fuels for different tissues? (brain, RBCs, liver, heart, muscle)
Brain = glucose (cannot use fatty acids)
RBCs = glucose
Liver = mostly fatty acids
Heart = mostly fatty acids
Muscle = mostly fatty acids at rest, mix of fatty acids and glucose (mobilised glycogen) during exercise
