In what physiological condition (fed or fasted) and in what tissues does lipolysis occur?
Occurs in the fasted state in the adipose tissue
Does a low carb diet induce lipolysis?
Yes because when there isn't a lot of glucose around the body needs to break down TAGs to be used for energy
How is lipolysis regulated by hormones (insulin, glucagons and catecholomine)?
A decrease in insulin will cause HSL-deP to be inactive.
An increase in glucagon and catecholamines will cause HSL-P to be activated
Together this causes an increase in TAGs being broken down to 3FFA + glycerol which will be converted to FFA
What is the difference between HSL and LPL? (HSL)
HSL hyrodlyzes fatty acids at the sn1 and sn3 position; catalyzes the release of the second fatty acid from DAG and release 1 FA forming MAG: key enzyme for breaking down TAGs into FA and glycerol needs to be phosphorylated. THis occurs in the adipose tissue when hormones epinephrine and glucagon are high
What is the difference between HSL and LPL? (LPL)
Synthesized and secreted into the circulation by adipose tissue and muscle; catalyzes the hydrolysis of TAGs to FFA and glycerol
Located in the luminal face of the endothelial cells of capillaries. Translocates to the surface of lipid droplets upon hormonal stimulation
Activated when in the fasted state and control uptake of FA; Fed state increased in adipose tissue; fasted state: increased in muscle
In what physiological conditions (fed or fasted state) and in what tissues does fatty acid oxidation increase?
In the fasting state in the muscle and liver
What is the relationship between fatty acid oxidation and plasma FFA?
As plasma levels of FFA increase, FA oxidation increases; plasma level of FFA are high in starvation and low in postprandial (fasting state)
How does malonyl CoA regulate CPT1?
Increased malonyl-CoA levels during fed inhibits CPT1 (acetyl-CoA from glycolysis from high carb diet)
If CTP1 activity is decreased, decrease in fatty acyl molecules going to mitochondria. Then decreased malonyl CoA levels during fasted stated stimulates CPT1 activity
Are odd chain fatty acids glucogenic?
Yes because odd chain fatty acids are oxidized and produce acetyl CoA molecules and addition 3 C molecules - precursor for gluconeogenesis
In what physiological conditions (fed or fasted state) and in what tissues does ketone body synthesis occur?
Fasted state in the mitochondria of the liver
How was this substrate produced?
In the well fed state acetyl CoA is produced during beta oxidation
In the fasted state fatty acid mobilization increases and the liver converts acetyl CoA to ketone bodies
What is the principal driver of ketone body synthesis?
Increased free fatty acids during prolonged starvation
Can the liver utilize ketone bodies? Why or why not?
The liver cannot because it doesn't have succinyl CoA transferase however the liver produces ketone bodies
What are ketone bodies?
Water soluble metabolites of fatty acids that are readily transported to other organs for oxidation of CO2 and H2O
What is the major lipid component of chyomicrons?
Highest % weight triacylglycerols