fuel storage with insulin Flashcards
What are our fuel reserves and the reasons why we require these
Glucose reserves:
small amount in glycogen 0.22Kg
small amount more made through gluconeogenesis
adipose:
large fuel reserves, TAGs 15Kg
Require for states of fasting and starvation:
10,000Kj energy used per day - we require energy avalipbe constantly
How can glucose be stored in adipose tissue
stored in adipose as TAGs
Uptaken glucose enters glycolysis leads to G-3-P which used in denovo lipolysis as glcerol blackbone
pyruvate used to denovo lipogenesis -> acetyl-coA coverted into FFA (reverse beta oxidation)
FFA from denovo lipogenesis + uptake from blood + glycerol -> TAGs -> stored in adipose
Where is glucose stored and how
Stored in the muscles and liver as glycogen
Branch change glucose polymer- 1-4 & 1-6 bonds (1-6 at branching)
Liver - stored as glycogen used to regulate blood glucose levels
skeletal muscle - stored glycogen, cannot be release as no glucose-6-phosphotase enzyme
How does the liver store and release excess glucose
Creates excess Acetyl-coa, used to make FFA converted to TAG -> released in VLDL broken down by lipoprotein lipase (LPL) at adipose tissue -> stored as TAGs
How is glycogen sythesised
Glucose diverted from glycolysis G-6-P -> G-1-P -> UDP-Glucose (UTP)
hexokinase + mutase
UDP remove -> glucose added to end of chian via glycosidic bond
branching enzyme makes new branches
How does insulin help to promote adipose and glycogen sythesis
Fat synthesis:
1. promote GSV movement increasing GLUT4 and glucose intake
2. stimulates glycolysis via hexokinase stimulation
3. stimultaes Lipoprotein lipase -> increased TAG breakdown and absoption
Glycogen synthesis:
1. Inhibits glucogen synthase kinase (GSK) -> prevents phosphorylation to keep glycogen synthase active. - glycogen synthase inactive form is phosphorylated
2. phosphatases activated to dephosphrylate any inactive glycogen synthases
