Lipid Transport Flashcards
What is the function of free fatty acids?
Act as ligands for transcription factors involved in energy metabolism especially polyunsatured FA
e.g role in regulating insulin metabolism
They upregulate lipid oxidation in liver and downregulation of lipogenesis in liver and adipose tissue
How are free fatty acids formed?
Form triacylglycerides stored in adipose tissue
Why are FA circulates bound to the serum albumin protein?
When transported on their own FA circulates will be transported as a Na+ salt bound to albumin. Unbound FA will act as a detergent and disrupt the cell membrane
What is the role of lipoproteins?
Transports triacylglyercerides and cholesterol in the blood between all tissues of the body mainly liver and adipocytes of adipose tissue
What are the five types of lipoproteins?
Chylomicrons VLDL IDL LDL HDL
What is the composition of a lipoprotein
Contains cholesterol ester, phospholipid, cholesterol and triacylglycerol aswell as apolipoprotein (different types of apolipoprotein depending on the type of lipoprotein e.g chylomicrons contain B48 only and have highest TG content)
What lipoprotein has the greatest density?
The lipoprotein with the greatest protein content which are HDLs
What are apolipoproteins?
Enable lipids to be soluble in an aqueous environment
Act as enzymes or co-factors for enzymes e.g ApoC2 and LPL
Tissue targeting e.g ApoE binds to Apo E receptors and enables cholesterol transfer
How are chylomicrons synthesised?
Carries lipids consumed from the diet hence a dietary lipid. Formed by the cells that line the gut. Apoliprotein is synthesised in the RER and packaged in the SER. Is released into the lymphatic system already associated with B48 where it will interact with HDL which will donate ApoE and ApoC2 to form a mature chylomicron
What are the features of chylomicrons?
High in TG content
Contain fat soluble vitamins A and E = inhibits the oxidation of lipids contained inside them = important as it prevents the deposition of fats
SHORT LIFE CYCLE (1hr) TG inside them have a life cycle of 5mins
What is the significance of chylomicrons being secreted by reverse pinocytosis in lymphatics?
Will drain into a thoracic duct and are carried to the superior vena cava = by this pathway the dietary chylomicron fats will bypass direct delivery to the liver and circulate once before the liver sees them therefore is made available to extrahepatic tissue.
(Different to carbohydrates which are released into the portal bein and directly delivered to the liver
