Dietary triglycerides are transported by
Ans. is 'a' i.e., Chylomicron : Chief carrier of exogenous TGs (dietary TGs) is -Chylomicrons*Chief carrier of endogenous TGs (i.e.,., synthesized in the liver) - VLDL*Circulation of lipids in the bodyLipid being insoluble (hydrophobic) cannot be transported in blood. So they are associated with 'polar' substances to form hydrophilic lipoprotein complexes 'Classification of lipoprotein on the basis of hydrated density: (As the proportion of lipids to protein decreases, the density of the lipoprotein complex increases)Chylomicrons lowest density*, highest content of lipids(TGs)*IDL (Intermediate density lipoproteins)LDL (low density lipoproteins)HDL (High density lipoproteins)After fat digestion, absorbed fatty acids are reesterified to form TGs and these TGs are converted to lipoprotein complex chylomicrons. These chylomicrons pass to blood circulation through the lymphatic ducts. In the capillaries, lipoprotein lipase (present on the surface of the endothelium) acts on the chylomicrons and removes most of the TGs from the chylomicrons Chylomicrons are thus converted into chylomicron remnants (CRs). There CRs are taken up by the liver.VLDLs are found in the liver and transport TGs formed in the liver to the extrahepatic tissues. In the blood capillaries, LPL acts on the YLDL and removes TGs from it. Thus VLDL is converted to IDL.Most of the IDL particles change into LDL (by losing their apoE and some of TGs). Some of IDL is taken up by liver and also the peripheral tissues.Most of LDL particles deliver the cholesterol to the extrahepatic tissues. Only some of the remaining LDL particles are taken up by the liver cells.HDL, is synthesized in the liver cells and removes cholesterol from the extrahepatic tissue and transfers it to the liver.So RememberMaximum exogenous TGs is seen in - Chylomicrons *Maximum endogenous TGs is seen in - VLDL* Maximum TGs is seen in - Chylomicrons*Maximum cholesterol is seen in - LDL*Cholesterol is transported from liver mainly as - VLDL*Carrier of cholesterol in plasma - LDL*Dietary cholesterol is transported to the extrahepatic tissues by - LDL*Cholesterol is transported from the extrahepatic tissues to the liver HDL*
Chylomicrons
VLDL
LDL
HDL
Cholesterol and Lipoproteins