Post on 08-Mar-2018
Lipid Transport Lipid Transport and Storageand Storage
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LIPIDS ARE TRANSPORTED IN LIPIDS ARE TRANSPORTED IN THE PLASMA AS THE PLASMA AS LIPOPROTEINSLIPOPROTEINS
Lipoproteins Consist of a Nonpolar Core & a Single Surface Layer of Amphipathic Lipids
The Distribution of Apolipoproteins Characterizes the Lipoprotein
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FREE FATTY ACIDSFREE FATTY ACIDS ARE RAPIDLY ARE RAPIDLY METABOLIZEDMETABOLIZED
TRIACYLGLYCEROLTRIACYLGLYCEROL IS IS TRANSPORTED FROM THE TRANSPORTED FROM THE INTESTINES IN CHYLOMICRONS & INTESTINES IN CHYLOMICRONS & FROM THE LIVER IN VERY LOW FROM THE LIVER IN VERY LOW DENSITY LIPOPROTEINSDENSITY LIPOPROTEINS
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Composition of the lipoproteinslipoproteins in plasma of humans.
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CHYLOMICRONSCHYLOMICRONS & VLDLVLDL ARE RAPIDLY CATABOLIZED
Triacylglycerols of Chylomicrons & VLDL Are Triacylglycerols of Chylomicrons & VLDL Are Hydrolyzed by Hydrolyzed by Lipoprotein LipaseLipoprotein Lipase
The Action of Lipoprotein Lipase Forms The Action of Lipoprotein Lipase Forms Remnant LipoproteinsRemnant Lipoproteins
The The LiverLiver Is Responsible for the Uptake of Is Responsible for the Uptake of Remnant LipoproteinsRemnant Lipoproteins
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Metabolic fate ofMetabolic fate of chylomicronschylomicrons
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Metabolic fate of Metabolic fate of VLDLVLDL and production of and production of LDLLDL
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LDLLDL IS METABOLIZED VIAIS METABOLIZED VIATHE THE LDL RECEPTORLDL RECEPTOR
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HDLHDL TAKES PART IN BOTH TAKES PART IN BOTHLIPOPROTEIN LIPOPROTEIN TRIACYLGLYCEROLTRIACYLGLYCEROL
& & CHOLESTEROLCHOLESTEROL METABOLISM METABOLISM
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CLINICAL ASPECTSCLINICAL ASPECTS
Imbalance in the Rate of TG Formation & Export Causes Fatty LiverFatty Liver
Ethanol Also Causes Fatty LiverFatty Liver
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ADIPOSE TISSUEADIPOSE TISSUE IS THE MAIN STOREOF TGTG IN THE BODY
The Provision of Glycerol 3-PhosphateGlycerol 3-Phosphate Regulates Esterification: Lipolysis Is Controlled by Hormone-Sensitive LipaseHormone-Sensitive Lipase (Figure 25–7)
Increased GlucoseGlucose Metabolism Reduces the Output of Free Fatty Acids
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HORMONESHORMONES REGULATEFAT MOBILIZATION
InsulinInsulin Reduces the Output of Free Reduces the Output of Free Fatty AcidsFatty Acids
Several HormonesSeveral Hormones Promote Lipolysis Promote Lipolysis
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LipolysisLipolysis increased by:
Epinephrine Norepinephrine Glucagon ACTH TSH Thyroid hormone
GH MSH Vasopressin Caffeine Theophylline Leptin
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LipolysisLipolysis decreased by:
Insulin Nicotinic acid Prostaglandin E1
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BROWN ADIPOSEBROWN ADIPOSE TISSUE TISSUEPROMOTES PROMOTES THERMOGENESISTHERMOGENESIS
Brown adipose tissue is involved in metabolism particularly at times when heat generation is necessary
Though not a prominent tissue in humans, it is present in normal individuals, where it could be responsible for “diet-induced thermogenesis.”
It is noteworthy that brown adipose tissue is reduced or absent in obese persons.
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The tissue is characterized by: well-developed bloodblood supply
high content of mitochondriamitochondria and cytochromescytochromes
but low activitylow activity of ATP synthase.
A thermogenic uncoupling protein, thermogeninthermogenin, acts as a proton conductance pathway dissipating the electrochemical potential across the mitochondrial membrane
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Thermogenesis increased by:
NorepinephineNorepinephine
FFAFFA
Acyl-CoAAcyl-CoA
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Thermogenesis decreased by:Thermogenesis decreased by:
Purine nucleotidesPurine nucleotides
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THE ENDTHE END