Energy Production Lipids Flashcards
(18 cards)
How are TAGs stores?
In anhydrous form in adipose tissue as they are hydrophobic
How is storage controlled?
Storage is under hormonal control
Insulin promotes storage
Glucagon, adrenaline, cortisol, growth hormone and thyroxine reduce storage
How are TAGs catabolised?
TAGs are hydrolysed by pancreatic lipase in the small intestine this releases glycerol and fatty acids.
What then happens to glycerol?
Glycerol is transported in the blood to the liver where it is metabolised.
Glycerol —-> glycerol phosphate (glycerol kinase)
Then either :
- Dihydroxyactone phosphate (DHAP)
-TAG synthesis
Where does b oxidation occur?
Mitochondria
Therefore what cells can’t do b-oxidation?
RBC no mitochondria
CNS fatty acids can’t cross blood brain barrier
How are fatty acids activated?
Activated by linking to acetyl~CoA which requires ATP and catalysed by fatty acyl~CoA synthase
How do activated fatty acids enter the mitochondria ?
Fatty acids shuttled across IMM via carnitine and is regulated my malonyl~CoA
^malonyl~CoA =inhibits
And it’s role is too prevent newly synthesised fatty acids in cytoplasm entering
What happens in B-oxidation?
Sequence of reactions that oxidise the fatty acid removing a C2 (acetate)repeatedly = giving reducing power in the form FAD2H and NADH
Acetate –> acetyl~CoA –> enter TCA cycle
The 3 ketone bodies produced in the body are……
Acetoacetate
Acetone
B-hydroxybutyrate
What are they formed from?
Hydroxymethyl glutaric acid
Where are they formed ?
- Acetoacetate+B-hydroxybutyrate are synthesised in the liver
- Acetone comes from the spontaneous decarboxylation of Acetoacetate
What is the normal level of ketone body ?
<1 mM
When can they increase and what to?
- in starvation to 2-5mM
* untreatedvtype 1 diabetes >10mM =ketoacidosis and can smell acetone on breath
What is ketone body synthesis controlled by?
Insulin:glucagon ratio
^ratio = lyase inhibited and reductase activated
Synthesis of ketone bodies requires….
- fatty acids to be available for oxidation in the liver following excessive lipolysis in adipose tissue =substrate
- plasma insulin:glucagon ratio to be low
Who can use ketone bodies?
*all tissues containing mitochondria including the CNS
What can ketone bodies be converted to ?
Acetyl~CoA via stage 3 catabolism
