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2015-06-30 16:41:23
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  1. Lipid digestion is __ in the mouth and stomach; lipids are __ to the small intestine __.
    • minimal
    • transported
    • essentialy intact
  2. emulsification
    mixing of two normally immiscible liquids (fat and water) to increase the surface area of the lipid, permitting greater enzymatic interaction and processing; aided by bile
  3. bile
    contains bile salts, pigments, and cholesterol

    secreteed by the liver and stored in the gallbladder
  4. Pancrease secretes what to hydrolyze lipids?
    pancreatic lipase, colipase, and cholesterol esterase
  5. miclees
    water-soluble spheres with a lipid-soluble interior; vital in digestion, transport, absorption of lipid-soluble substances starting from teh duodenum all the way to the end of the ileum
  6. Where are micelles absorbed?
    at the brush border of teh intestinal mucosal cells, where they are absorbed into teh mucosa and re-esterified to form triacylglycerols and cholesteryl esters and packaged into chylomicrons
  7. Chylomicrons leave the intestine via __, the vessels of teh lymphatic system, and re-enter the bloodstream via the __, a long lymphatic vessel that empties into the left __  at the base of the neck.
    • lacteals
    • thoracic duct
    • subclavian vein
  8. In the postabsorptive state, what happens?
    fats are released from adipose tissue and used for energy
  9. Although human adipose tissue does not respond directly to glucagon, a fall in insulin levels activates a __ that hydrolyzes triacylglycerols, yielding __ and __. 

    __ ad __ can also activate HSL.
    • hormone-sensitive lipase
    • epinephrine and cortisol
  10. Released glycerol from fat may be transported to theliver for _ or __.
    glycolysis or gluconeogenesis
  11. LPL
    necessary for teh metabolism of chylomicrons andVLDL

    it is an enzyme that can release free fatty acids from triacylglycerols in these lipoproteins
  12. How are free fatty acids transported through the blood?
    in association with albumin, a carrier protein
  13. How are triacylglycerol and cholesterol transported in the blood?
    as lipoproteins: aggregates of apolipoproteins and lipids
  14. chylomicron function
    transport dietary Triacylglycerols and cholesterol from intestine to tissues
  15. VLDL
    transport triacylglycerols from liver to tissues
  16. IDL
    pick up cholesterol from HDL to become LDL; picked up by the liver
  17. LDL
    deliver cholesterol into cells
  18. HDL
    • pick up cholesterol accumulating in blood vessels
    • delivers cholesterol to liver and steroidogenic tissues
    • transfers apolipoproteins to other lipoproteins
  19. Some IDL is what?
    reabsorbed by the liver by apolipoproteins on its exterior, and some is further processed in the bloodstream

    It is thus a transition particle between triacylglycerol transport (associated with chylomicrons adn VLDL) and cholesterol transport (associated with LDL and HDL)
  20. HDL contains __ used for __.

    cholesterol recovery, that is, teh cleaning up of excess cholesterol from blood vessels for excretion
  21. What are apolipoproteins?
    receptor molecules and are involved in signaling
  22. LCAT
    an enzyme that catalyzes cholesterol esterification

    activated by HDL apoproteins

    adds a fatty acid to cholesterol to produce soluble cholesteryl esters
  23. Explain de novo synthesis of cholesterol.
    it occurs in the liver and is driven by acetyl-CoA adn ATP

    The citrate shuttle carries mitochondrial acetyl-CoA into teh cytoplasm, where synthesis occurs, using NADPH as a reducer
  24. RLS in cholesterol synthesis
    synthesis of mevalonic acid in the SER; catalyzed by HMG CoA reductase
  25. What promotes cholesterol synthesis?
  26. CETP
    facilitates the transfer of cholesterols from HDL to LDL
  27. What are two important essential fatty acids?
    alpha-linolenic acid and linoleic acid

    both are polyunsaturated fatty acids
  28. What does the omega in the omega numbering system indicate?
    the position of the last double bond relative to teh end of the chain
  29. Where does fatty acid biosynthesis occur? 

    Where are its products transported?
    in the liver

    to adipose tissue for storage
  30. What are teh two major enzymes of fatty acid synthesis?
    • acetyl-CoA carboxylase
    • fatty acid synthases
  31. What is the primary end product of fatty acid synthesis?
    palmitic acid (palmitate)
  32. Int he cytosol, if there is an accumulation of citrate, what can happen?
    citrate lyase splits citrate back into acetyl-CoA and OAA, the latter of which can return to teh mitochondrion to continue moving acetyl CoA
  33. acetyl-CoA carboxylase
    activates acetyl-CoA in the cytoplasm for incorporation into fatty acids

    rate limiting enzyme of fatty acid biosynthesis

    activated by insulin and citrate
  34. fatty acid synthase (aka: palmitate synthase)
    palmitate is teh only fatty acid that humans can synthesis de novo; in teh cytosol; induced after a meal high in carbs due to elevated insulin levels

    contains an acyl carrier protein and uses NADPH
  35. Explain production of palmitate
    eight acetyl-CoA groups are required to produce it. 

    steps involve: attachment to ACP, bond formation between activated malonyl CoA and teh growing chain, reduction of carboxyl group, dehydration, reduction of the double bond
  36. alpha-oxidation
    branched chain fatty acids undergo this
  37. omega oxidation
    occurs in ER to produce dicarboxylic acids
  38. What number chain fatty acids can't diffuse freely into the mito?
    14 to 20 carbons; they require the carnitine shutle
  39. Beta oxidation
    repetition of four steps

    each four step cycle releases one acetyl-CoA adn reduces NAD+ and FAD, which are oxidized int eh ETC, producign ATP

    • 1) Oxidation of fatty acid to form a double bond
    • 2) Hydration of double bond to form hydroxyl grou
    • 3) oxidation of hydroxyl group to form carbonyl
    • 4) splitting into shorter acyl CoA and acetyl CoA
  40. DIn muscle and adipose tissue, acetyl-CoA does what?
    enters the CAC
  41. In the liver, acetyl-CoA does what?
    stimulates gluconeogenesis by activating pyruvate carboxylse because it can't be converted to glucose
  42. In a fasting state, the liver does what?
    produces more acetyl-Coa by beta ox than is used in the CAC. The acetyl CoA is then used to synthesize ketone bodies
  43. Difference between odd number fatty acids and even numbered?
    durign the final cycle, odd-numebred fatty acids yield one acetyl-CoA and one propionyl-CoA, which is converted to methylmalonyl-CoA-->converted to succinyl CoA
  44. What must unsaturated fatty acids undergo?
    they rearrange cis double bonds at the 3,4 position to trans double bonds at the 2,3 position
  45. For conjugated double bonds, what must happen?
    2,4-dienoyl-CoA reductase converts two conjugated double bonds to just one double bond at the 3,4 position
  46. In the fasting state, the liver converts excess acetyl-CoA from beta ox of fatty acids intot eh __.
    ketone bodies acetoacetate adn 3-hydroxybutyrate, which can be used for energy in various tissues
  47. What can cardiac tissue do with the ketones?
    can metabolize it to acetyl-CoA
  48. After a week of fasting, ketones reach a concentration in the blood that is high enough for the __.
    brain to begin metabolizing them
  49. ketogenesis
    occurs in the mito of liver cells when excess acetyl-CoA accumulates in the fasting state
  50. During ketolysis, what happens to 3-hydroxybutyrate?
    it is oxidized to acetoacetate
  51. Ketolysis in the brain
    brain derives 2/3 energy from ketone bodies, metabolizing it to acetyl-CoA, inhibiting pyruvate dehydrogenase

    glycolysis and glucose uptake in the brain decreases
  52. Absorption of amino acids and small peptides through the luminal membrane is accomplished by __.
    secondary active transport linked to sodium
  53. glucogenic amino acids
    can be converted into glucose through gluconeogenesis

    all but leucine and lysine
  54. ketogenic amino acids
    can be converted into acetyl-CoA and ketone bodies

    Leu, Lys, Isl, Phe, Thr, Trp, Tyr