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15 Cards in this Set
- Front
- Back
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unique feature of ketone metabolism
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synthesis is uncontrolled
-overflow pathway for ACoA (from excessive FA ox) |
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examples of ketones
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acetoacetate
beta hydroxybuterate (spon from acetoacetate) acetone |
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characteristics of beta hydroxybuterate
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very high energy
(more than acetoacetate-24 ATP) (27 ATP equivs) predominates in blood |
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function of ketones
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heart, muscle & brain (pituitary) use for energy
liver can't oxidize them fuel (metabolite) nitroprusside test genesis is source of H+ cation depletion (problem) (urinary ketone bodies, anionic) |
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mechanism to combat acidosis
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glutaminase & glutamate Dh
in renal cortex H+ excreted via urine alpha ketoglutarate used for gluconeogenesis ketogenesis inhibits urea cycle by using cytosolic glutamate for amonia removal |
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ketosis
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never underutilized
(problems always from overproduction) produced in liver, kidney (& brain) liver can't oxidize |
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# ketones produced from beta oxidation
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4
(should only be 1) |
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ketone body ratio
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beta hydroxybutyrate/acetoacetate
measurement of redox state of cell (analogous to lactate/pyruvate ratio) |
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ketogenesis (enzymes)
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ACoA (from beta ox, some PD)
beta keto thiolase (also in beta ox) HMG CoA synthase HMG CoA lyase beta hydroxybutyrate DH in liver mitochondria |
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ketogenesis (products)
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ACoA to beta hydroxybutyrate
ACoA acetoacetyl CoA HMG CoA Acetoacetate beta hydroxybutyrate |
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fates of ACoA in metabolism
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(from beta oxidation & pyruvate DH)
via ketothiolase FA synth Cholest synth ketone synth |
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utilization of ketones (enzymes)
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SCFA (no transporter needed)
convert (to acetoacetate) via beta HBDh trap (w/CoA- get NADH) -use acyl transferase or thiokinase release ACoA (via ketothiolase) |
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ketone enzymes not found in liver
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to trap acetoacetate w/CoA
acyl transferase -transfer CoA to Acetate from SCoA or -thiokinases |
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utilization of ketones (products)
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beta hydroxybutyrate
acetoacetate acetoacetyl CoA |
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fasting/starvation & ketone bodiesq
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liberate TAGs
FA to liver & musc (via albumin) -give ACoA for KB in liver -gives ACoA for TCA in musc glycerol to liver makes glucose for blood KBs from liver to muscle |
