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Biochemistry FA > Fatty Acid Metabolism / Ketone Bodies / lipid transport > Flashcards

Fatty Acid Metabolism / Ketone Bodies / lipid transport Flashcards

1
Q

Long-chain fatty degradation requires

A

Carnitine dependent transport into mitochondrial matric

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1
Q

Inhibitor of carnitine acytransferase

A

Malonyl-coa

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2
Q

Steps of long chain degradation (and location

A
  1. Fatty acid + coa –> Fatty acyl - coa (fatty acid coa synthase) (cytoplasm)
  2. Carnitine dependent transportof Fatty acyl - coa into mitochondria
  3. β-oxidation –> Fatty acyl - coa –> Acetyl coa (Acyl CoA dehydrogenase)
  4. Acetyl coa –> Ketone bodies and TCA cycle
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4
Q

Systemic 1ry Carnitine deficiency - symptoms

A
  1. Weakness
  2. Hypotonia
  3. Hypoketotic hypoglycemia
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4
Q

Acyl-coa dehydrogenase

A

Initial enzyme for β-oxidation

FAD to FADH2

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5
Q

Systemic 1ry Carnitine deficiency - pathophysiology

A

Inherited defect in transport of long chain fatty acids into the mitochondria –> toxic accumulation

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7
Q

Medium-chain acyl-coa dehydrogenase deficiency - pathophysiology / mode of inheritance / presentation

A

AR disorder of fatty acid oxidation –> decreased ability to break down fatty acids into acetyl coa –> accumulation of 8- to 10 - carbon fatty acyl carnites and hypoketotic hypoglycemia
may present in infancy or early childhood with vomiting, lethargy, coma + liver dysfunction –> can leat to sudden death

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8
Q

Mechanism of hypoglycemia in acyl-coa dehydrogenase deficiency

A

Acetyl coa is an +allosteric regulator of pyruvate carboxylase

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8
Q

Ketogenesis fuel and purpose (and location)

A

N the liver, fatty acids and amino acids are metabolyized to acetoacetate and β hydroxybutyrate (to be used in muscle and brain)

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10
Q

Ketogenesis fuel and purpose (and location)

A

In the liver, fatty acids and amino acids are metabolyized to acetoacetate and β hydroxybutyrate (to be used in muscle and brain)

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11
Q

Breath with ketones

A

Smells loke acetone (fruity odor)

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12
Q

types of ketone bodies (and urine test)

A

types: acetoacetate and β hydroxybutyrate

Urine test does not detect β hydroxybutyrate

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12
Q

Ketogenesis in alcoholism

A

Excess NADH shunts oxaloacetate to malate . Buildup of acetyl coa which shunts glucose and FFA toward the production of ketone bodies

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13
Q

3 main situations of ketogenesis (why)

A
  1. Prolonged starvation (depletion of oxaloacetate for gluconeogenesis)
  2. Diabetic ketoacidosis (depletion of oxaloacetate for gluconeogenesis)
  3. Alcoholism (excess NADH shunts oxaloacetate to malate
    - -> buildup of acetyl-coa
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14
Q

Ketogenesis in prolonged starvation and diabetic ketogenesis

A

Oxaloacetate is depleted for gluconeogenesis. Buildup of acetyl coa which shunts glucose and FFA toward the production of ketone bodies

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16
Q

Ketogenesis in the liver - steps and metabolism

A

FA, aminoacids –> Acetyl-Coa –> HMG-CoA (HMG-CoA synthase) –> Autoacetate –> β-Hydroxybutyrate –> acetone (blood) –> expired by lungs
at extra hepatic tissue: β-Hydroxybutyrat –> acetoacetate –> Acetoacetyl-Coa (through TCA) –> Acetyl - Coa –> TCA

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17
Q

1g carbohydrate, 1g fat, 1g protein

A

fat –> 4 kca, carbohydrate –> 4 kca, alcohol –> 9Kcal

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17
Q

Metabolic priorities for fasting and starvation

A

Supply sufficient glucose to the brain and RBC and to preserve protein

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18
Q

energy source at exercise (time)

A

Ovreal performance: 0-1min declining and after plateau (peak at 0)
ATP: 0-2 sec (peak at 0)
Creatine phosphate: 0-10 sec (peak at 2)
aerobic metabolism: O-… (peak at 50 sec and then plateau)
Anaerobic metabolism: 0-1mon (peak at 25 sec)

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20
Q

Fed state (after a meal regulation) mechanism / regulation

A

Glycolysis and aerobic respiration

Insulin stimulates storage of lipids, proteins, glycogen

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21
Q

Fasting state (between meals) mechanism / regulation

A

Major: hepatic glycogenolysis
Minor: hepatic gluconeogenesis, adipose release of FFA
Glucagon, adrenaline stimulate use of fuel reserve

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22
Q

Fasting state (between meals) mechanism is regulated by

A

Glucagon, adrenaline stimulate use of fuel reserve

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22
Q

Glycogen serve depleted after how long

A

1 day

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23
Q

RBC cannot use ketones because

A

They lack mitochondria

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24
Q

Starvation after 3 days

A 
Adipose stores (ketone bodies become the main source)
After these are depleted, vital protein degration leading to organ faillure and death
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25
Q

Starvation day 1-3 Blood glucose maintained by

A
  1. hepatic gluconeogenesis
  2. Adipose relase of FFA
  3. Muscle and liver, which shift fuel use from glucose to FFA
  4. Hepatic gluconeogenesis from peripheral tissue lactate and alanine, and from adipose tissue glycerol and propionyl coa (from odd-chain FFA)
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26
Q

What does determine survival time at starvation

A

Amount of excess stores

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27
Q

Cholesterol synthesis rate limiting step is catalyzed by

A

HMG-CoA reductase

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28
Q

HMG-CoA reductase reaction

A

HMG-CoA to mevalonate

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29
Q

HMG-CoA regulation

A

Insulin+
Thyroxine +
Cholesterol -
Glucagon -

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30
Q

LCAT

A

lecithin cholesterol acyltransferase

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31
Q

2/3 of plasma cholesterol is esterified by

A

Lecithin cholesterol acyltransferase (LCAT)

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33
Q

LCAT reaction

A

Cholesterol to cholesterol ester

34
Q

Statins mechanism of action

A

HMG-CoA reductase inhibitor

35
Q

Cholesterol use

A

needed to 1. maintain cell membrane integrity, and to

2. synthesize bile acid, 3. steroids, and 4. vit D

36
Q

CETP

A

Cholesterol ester transfer protein

37
Q

CETP function

A

Mediates transfer of cholesterol esters to other lipoprotein particles and TGs to HDL

38
Q

type of lipases

A
  1. Pancreatic lipase
  2. Lipoprotein lipase (LPL)
  3. Hepatic TG lipase
  4. Hormone sensitive lipase
39
Q

type of lipases and their action

A
  1. Pancreatic lipase –> Degradation of dietary triglycerides in small intestine
  2. Lipoprotein lipase (LPL) –> Degradation of TG circulating In chylomicrons and VLDLs. Found on vascular endothelial surface
  3. Hepatic TG lipase –> Degradation of TG remaining in IDL
  4. Hormone sensitive lipase –> Degradation of TG stored in adipocytes
40
Q

Nascent HDL is produced from

A

Liver, intestine

41
Q

Nascent to mature HDL - enzyme

A

Lecithin cholesterol acyltransferase (LCAT)

42
Q

mature HDL - next step

A

CETP (Cholesterol ester transfer protein): mediates transfer of cholesterol esters to other lipoproteins particles (to VLDL, IDL, LDL)

43
Q

Major apolipopoteins - types

A

E, A-I, C-II, B-48, B-100

44
Q

Lipd particles

A
  1. Chylomycron
  2. Chylomycron remnants
  3. VLDL
  4. IDL
  5. HDL
  6. LDL
45
Q

Apolipoprotein E function

A

Mediates remnant uptake

46
Q

Apolipoprotein E is found at (particles)

A
  1. Chylomycron
  2. Chylomycron remnants
  3. VLDL
  4. IDL
  5. HDL
    (all except LDL)
47
Q

Apolipoprotein A-1 function

A

Activates Lecithin cholesterol acyltransferase (LCAT) – Cholesterol to cholesterol ester

48
Q

Apolipoprotein A-1 is founded

A

Chylomicrons

HDL

49
Q

Apolipoprotein C-II function

A

Lipoprotein lipase cofactor

50
Q

Apolipoprotein C-II is founded

A

Chylomicrons, VLDL, HDL

51
Q

Apolipoprotein B-48 function

A

Mediates chylomicrons secretion

52
Q

Apolipoprotein B-48 is founded

A
  1. Chylomycron

2. Chylomycron remnants

53
Q

B100 function

A

Binds LDL receptor

Composition and secretion of VLDL

54
Q

B100 is founded

A

VLDL
IDL
LDL

55
Q

Lipoproteins are composed of

A

Varying proportions of cholesterol, TGs and phospholipids

56
Q

Lipoproteins that carry the most cholesterol

A

LDL

HDL

57
Q

Transports cholesterol from liver to tissues

A

LDL

58
Q

Transports cholesterol from tissues to the liver

A

HDL

59
Q

Chylomicrons function / mechanism / source

A

secreted by Intestinal epithelial cells –> Deliver dietary TGs to peripheral tissue and becomes chylomicron remnants (by LPL) –> Chylomicron remnants (mostly depleted of their TGs) –> Deliver cholesterol to liver

60
Q

VLDL function / source

A

secreted by liver –> Delivers hepatic TGs to peripheral tissue

61
Q

IDL function / source

A

formed in the degradation of VLDL (by LPL) –> Delivers TGs and cholesterol to liver

62
Q

LDL - function / source

A

Formed in the degradation of IDL (by HL in the liver and the peripheral tissue). Delivers hepatic cholesterol to peripheral tissues –> taken up by target cells via receptor-mediated endocytosis

63
Q

HDL function

A
  1. Cholesterol transport from cholesterol transport from peripheral tissue to liver
  2. Act as a repository for apoC and apoE (needed for chylomicrons and VLDL metabolism)
64
Q

……increases HDL synthesis

A

Alcohol

65
Q

HDL is secreted from

A

Liver

Intestine

66
Q

Familial dyslipidemias - types and mode of inheritance

A
  • type 1 (Hyperchylomicronemia) - AR
  • type 2a (hypercholesterolemia) - AD
  • type 4 (Hypertriglyceridemia) - AD
67
Q

Familial dyslipidemias - type 1 (Hyperchylomicronemia) - pathogenesis

A

LPL or APO C-II deficiency

68
Q

Familial dyslipidemias - type 1 (Hyperchylomicronemia) - labs

A
  • Increased 1. Chylomycrons, 2. TG, 3. cholesterol in blood

- Creamy layer is supernatant

69
Q

Familial dyslipidemias - type 1 (Hyperchylomicronemia) - clinical presentation

A
  1. Pancreatitis
  2. Hepatosplenomegaly
  3. eruptive/pruritic xanthomas
    (NO HIGH RISK FOR ATHEROSCLEROSIS)
70
Q

Familial dyslipidemias - type 2a (hypercholesterolemia) - pathogenesis

A

Absent or defective LDL receptors

71
Q

Familial dyslipidemias - type 2a (hypercholesterolemia) - lab

A

High 1. LDL 2. cholesterol

72
Q

Familial dyslipidemias - type 2a (hypercholesterolemia) - values of cholesterol

A

heterozygotes –> 300mg/dl

homozygous –> 700+ mg/dl

73
Q

Familial dyslipidemias - type 2a (hypercholesterolemia) - heterozygous vs homozygous according to frequency and values of cholesterol

A

heterozygotes –> 1:500 –> 300mg/dl

homozygous –> very rare –> 700+ mg/dl

74
Q

Familial dyslipidemias - type 2a (hypercholesterolemia) - clinical presentation

A
  • accelerated atherosclerosis (may have MI before 20)
  • tendon (Achilles) xanthomas
  • corneal arcus
75
Q

Familial dyslipidemias - type 4 (Hypertriglyceridemia) - pathogenesis

A

Hepatic overproduction of VLDL

76
Q

Familial dyslipidemias - type 4 (Hypertriglyceridemia) - labs

A
  • High 1. VLDL, 2. TG

- Hypertriglyceridemia (more than 1000)

77
Q

Familial dyslipidemias - type 4 (Hypertriglyceridemia) - clinical presentation

A

pancreatitis

78
Q

Familial dyslipidemias - types and pathogenesis (and mode of inheritance)

A
  • type 1 (Hyperchylomicronemia) - AR –> LPL or apoC-II deficiency
  • type 2a (hypercholesterolemia) - AD –> Absent or deficient LDL receptors
  • type 4 (Hypertriglyceridemia) - AD –> Hepatic overproduction of VLDL
79
Q

Familial dyslipidemias - types and clinical presentation

A
  • type 1 (Hyperchylomicronemia) –> pancreatitis, hepatosplenomegaly, eruptive/pruritic xanthomas
  • type 2a (hypercholesterolemia) –> accelerated atherosclerosis (may have MI before 20), tendon (Achilles) xanthomas, corneal arcus
  • type 4 (Hypertriglyceridemia) –> pancreatitis
80
Q

Fatty acid metabolism 1ry occurs in

A
  1. liver
  2. lactating mammary glands
  3. adipose tissue
81
Q

fatty acid synthesis

A

citrate (mit) –> to cytoplasm through mit membrane –> acetyl-coa (ATP citrate)
acetyl coa + Biotin + CO2 –> Malonyl-CoA –>
fatty acid synthesis (palmitate, a 16C FA)

82
Q

Medium-chain acyl-coa dehydrogenase deficiency - treatment

A

treat by avoiding fasting

Biochemistry FA (16 decks)

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