Physical Activity and Lipoprotein Metabolism Flashcards
What happens to risk of CHD as TAG level increases?
Risk of CHD increases
Why does it take longer for TG to appear in the blood (compared to glucose for example)?
TG are packaged in chylomicrons and have to pass through the lymphatic system and thoracic duct before entering bloodstream
How does the liver produce FFAs?
Liver has lipases, therefore when chylomicron (containing TG) passes through, fatty acids are broken off TG molecule.
What does liver do with excess fat after a meal?
Produces apo B100 (apolipoprotein) and repackages fatty acid back as TG, forming a VLDL. This is back in the circulation.
What does LPL (lipoprotein lipase) do?
Frees fatty acids from TG molecule, making them available (to muscle for oxidation, for example).
How is TAG and cholesterol transferred between lipoproteins?
In the blood, VLDL , LDL and HDL all bump into each other. As VLDL is packed with TAG it will knock this TAG onto other molecules, and in return receive their cholesterol. This process is made possible by cholesterol ester transfer protein (CETP).
What happens to TAG-rich HDL in Kidneys?
Catabolised - leading to fewer HDL particles.
What happens to TAG-rich LDL?
TAG gets hydrolysed leading to smaller, more dense LDL (far more dangerous!)
Why is having fewer HDL particles BAD?
- Less particles to engage in reverse cholesterol transport.
- HDL has antioxidant role on LDL
What is ‘postprandial lipaemia’?
Elevation of lipid in circulation seen in hours after eating a fat-containing meal.
When one exercises, what changes in terms of the livers response to fat?
The liver will esterify (put back into the blood) slightly less fat, and oxidise slightly MORE fat.
After exercise, where is more of your cardiac output directed to?
Liver
Regular exercise causes increased capillarisation, how does this have a positive impact?
Training increases LPL activity, this means improved delivery of FFA to active muscle.
What happens when VLDL interacts with LPL?
LPL will breakdown the TAG (producing FFA), but also transfer cholesterol from VLDL to HDL.
What does Hormone Sensitive Lipase (HSL) do?
Breaks down stored TG, in order for products to be released into the blood stream.
Essentially it ‘liberates’ fat from adipose tissue, putting it back into the blood stream.
