LipidMetabolismOverview andDiseases ofLipid Metabolism
Lipid Metabolism Overview and Diseases of Lipid Metabolism
Overview of lipidmetabolism Most important form of energy storage You'd have to store 67.5 lbs of hydrated glycogen to equal the energycontained in 10 lb of stored fat Relative proportion of stored energyCarbohydrates: 650 kcal [1 kcal = 1 cal (dietary))Protein:25,000kcalFat: 100,000 kcal
Overview of lipid metabolism Most important form of energy storage You’d have to store 67.5 lbs of hydrated glycogen to equal the energy contained in 10 lb of stored fat Relative proportion of stored energy • Carbohydrates: 650 kcal [1 kcal = 1 cal (dietary)] • Protein: 25,000 kcal • Fat: 100,000 kcal
Three sources Dietary triacylglycerols (TAGs) TAGs synthesized in liver TAGs stored in adipocytes Many diseases associated with disruptions in lipid metabolism
Three sources Dietary triacylglycerols (TAGs) TAGs synthesized in liver TAGs stored in adipocytes Many diseases associated with disruptions in lipid metabolism
Why Fatty Acids for energy storage?Tworeasons:: The carbon in fatty acids (mostly CH,) is almost completelyreduced (so its oxidation yields the most energy possible).·Fatty acids are not hydrated（水化）（as mono-andpolysaccharides are), so they can pack more closely in storagetissues
Why Fatty Acids for energy storage? Two reasons: • The carbon in fatty acids (mostly CH2) is almost completely reduced (so its oxidation yields the most energy possible). • Fatty acids are not hydrated（水化） (as mono- and polysaccharides are), so they can pack more closely in storage tissues
Fat fromDiet&AdiposeCellsTriacylglycerols either way: Triglycerides represent the major energy input in the modern diet(but it wasn't always this way).: Triglycerides are also the major form of stored energy in the body: Hormones (glucagon, epinephrine, ACTH) trigger the release of fattyacids from adiposetissue
Fat from Diet & Adipose Cells Triacylglycerols either way • Triglycerides represent the major energy input in the modern diet (but it wasn‘t always this way). • Triglycerides are also the major form of stored energy in the body. • Hormones (glucagon, epinephrine, ACTH) trigger the release of fatty acids from adipose tissue