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UWorld Review > Metabolism overview > Flashcards

Metabolism overview Flashcards

1
Q

Energy is extracted from food via

A

oxidation

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2
Q

4 stages of oxidation of food

A
  1. food is hydrolzyed in GI tract to monomeric building blocks
  2. building blocks degraded by various paths to make universal intermediate acetyl-CoA
  3. TCA cycle oxidizes acetyl-CoA to make CO2
  4. TCA cycle also makes 3 NADH and 1 FADH2 via dehydrogenases
  5. extraction of energy from food is ox. phosphorylation where energy of NADH and FADH2 released via ETC and used by ATP synthase to make ATP
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3
Q

What does mitochondria do

A
  1. FA oxidation (beta ox)
  2. acetyl-CoA production
  3. TCA
  4. ox. phosphorylation
  5. ketogenesis
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4
Q

what metabolism happens in cytoplasm

A
  1. glycolysis
  2. HMP shunt
  3. cholesterol synthesis (SER)
  4. protein synthesis (riubosomes, RER)
  5. FA’s
  6. nucleotides
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5
Q

What metabolic processes occur in both mitochondria and cytoplasm

A
  1. Heme synthesis
  2. Urea cycle
  3. Gluconeogenesis
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6
Q

When will sugars be used as source of acetyl-CoA to make ATP

A

when insulin is present

right after a meal

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7
Q

When is fat used as source of acetyl-CoA for ATP

A

inbetween meals when insulin is low

glucagon, cortisol, epinephrine are present

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8
Q

Fed state metabolism (after a meal)

A
  • glycolysis
  • aerobic respiration
  • insulin stimulates storage of lipids, proteins, glycogen
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9
Q

Fasting (between a meal) metabolism

A
  • hepatic glycogenolysis
  • hepatic gluconeogenesis
  • adippose release of FFA (minor)
    • glucagon and epinephrine stimulate use of fuel reserves
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10
Q

Starvation (1-3 days) metabolism

blood glucose levels maintained by

A
  • hepatic glycogenolysis
  • adipose release FFA
  • muscle and liver, shift fuel use from glucose to FFA
  • hepatic gluconeogenesis from peripheral tissue lactate and alanine
    • adipose tissue glycerol and propionyl CoA (from odd chain FFA)
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11
Q

Starvation after day 3

blood glucose levels maintained by

A
  • adipose stores = ketone bodies main source for brain
  • after adipose depleted, vital protein degradation accelerates = organ failure and death
  • amount of excess stores determines survival time
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12
Q

when will Glycogen stores will be depleted

A

after day 1

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13
Q

What is Kwashiorkor

A

severe protein malnutrition

  • skin lesions
  • edema d/t decreased plasma oncotic pressure
  • liver malfunction = fatty change
  • small child with swollen abdomen
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14
Q

Kwashiorkor liver malfunction d/t

A

decreased apolipoprotein synthesis causes fatty change

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15
Q

Kwashiorkor MEALS mneumonic

A

Malnutrition

Edema

Anemia

Liver (fatty)

Skin lesions (hyperkeratosis, dyspigmentation)

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16
Q

What is Marasmus

A

malnutrition that does not cause edema

diet is deficient in calories, but no nutrients entirely absent

17
Q

What does marasmus result in

A

muscle wasting

18
Q

Rate determining enzyme of glycolysis

A

phosphofructokinase-1

PFK-1

  • activated by: AMP, F-2,6-BP
  • deactivated by: ATP, citrate
19
Q

Rate determining enzyme of gluconeogenesis

A

Fructose-1,6-bisphosphatase

  • activated by: citrate
  • deactivated by: AMP, F-2,6-BP
20
Q

Rate determining enzyme of TCA cycle

A

Isocitrate dehydrogenase

  • activated by: ADP
  • deactivated by: ATP, NADH
21
Q

Rate determining enzyme of glycogenesis

A

glycogen synthase

  • activated by: G6P, insulin, cortisol
  • deactivated by: epinephrine, glucagon
22
Q

Rate determining enzyme of glycogenolysis

A

Glycogen phosphorylase

  • activated by: epinephrine, glucagon, AMP
  • deactivated by: G6P, insulin, ATP
23
Q

Rate determining enzyme of HMP shunt

A

G6PD

  • activated by: NADP+
  • deactivated by: NADPH
24
Q

Rate determining enzyme of de novo pyrimidine synthesis

A

Carbamoyl phosphate synthetase II

  • activated by: ATP, PRPP
  • deactivated by: UTP
25
Q

Rate determining enzyme of de novo purine synthesis

A

Glutamine-phosphoribosylphyrophosphate (PRPP) amidotransferase

  • deactivated by: AMP, IMP, GMP
26
Q

Rate determining enzyme of urea cycle

A

Carbamoyl phosphate synthetase I

  • activated by: N-acetylglutamate
27
Q

Rate determining enzyme of FA synthesis

A

Acetyl-CoA carboxylase (needs biotin)

  • activated by: insulin, citrate
  • deactivated by: glucagon, palmitoyl-CoA
28
Q

Rate determining enzyme of FA oxidation

A

Carnitine acyltransferase I

  • deactivated by: Malonyl-CoA
29
Q

Rate determining enzyme of ketogenesis

A

HMG-CoA synthase

30
Q

Rate determining enzyme of cholesterol synthesis

A

HMG-CoA reductase

  • activated by: insulin, thyroxine, estrogen
  • deactivated by: glucagon, cholesterol
31
Q

Glycolysis after arsenic ingestion makes how many ATPs

A

zero

32
Q

Aerobic metabolism makes how many ATP from 1 glucose

A

32 net ATP via malate-aspartate shuttle (heart/liver)

30 net ATP via glycerol-3-phosphate shuttle (muscle)

33
Q

Anaerobic glycolysis produces how many ATP

A

2 net ATP per glucose

34
Q

Nicotinamides (NAD+ and NADP+) are from

A

Vitamin B3

35
Q

Flavin nucleotides (FAD) is from

A

vitamin B2

36
Q

NAD+ is generally used in

A

catabolic proceses

carry reducing equivalents away as NADH

37
Q

NADPH is used in

A

anabolic processes (steroid and FA synthesis)

supply of reducing equivalents

38
Q

Where is NADPH made

A

HMP shunt in cytoplasm

39
Q

What are the 4 things NADPH is used in

A
  1. anabolic processes
  2. respiratory burst
  3. cytochrome P450 system
  4. glutathione reductase

UWorld Review (35 decks)

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