Fatty Acid Metabolism / Ketone Bodies / lipid transport Flashcards Preview

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Flashcards in Fatty Acid Metabolism / Ketone Bodies / lipid transport Deck (82)
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1

Long-chain fatty degradation requires

Carnitine dependent transport into mitochondrial matric

1

Inhibitor of carnitine acytransferase

Malonyl-coa

2

Steps of long chain degradation (and location

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

4

Systemic 1ry Carnitine deficiency - symptoms

1. Weakness
2. Hypotonia
3. Hypoketotic hypoglycemia

4

Acyl-coa dehydrogenase

Initial enzyme for β-oxidation
FAD to FADH2

5

Systemic 1ry Carnitine deficiency - pathophysiology

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

7

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

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

8

Mechanism of hypoglycemia in acyl-coa dehydrogenase deficiency

Acetyl coa is an +allosteric regulator of pyruvate carboxylase

8

Ketogenesis fuel and purpose (and location)

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

10

Ketogenesis fuel and purpose (and location)

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

11

Breath with ketones

Smells loke acetone (fruity odor)

12

types of ketone bodies (and urine test)

types: acetoacetate and β hydroxybutyrate
Urine test does not detect β hydroxybutyrate

12

Ketogenesis in alcoholism

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

13

3 main situations of ketogenesis (why)

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

14

Ketogenesis in prolonged starvation and diabetic ketogenesis

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

16

Ketogenesis in the liver - steps and metabolism

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

17

1g carbohydrate, 1g fat, 1g protein

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

17

Metabolic priorities for fasting and starvation

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

18

energy source at exercise (time)

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)

20

Fed state (after a meal regulation) mechanism / regulation

Glycolysis and aerobic respiration
Insulin stimulates storage of lipids, proteins, glycogen

21

Fasting state (between meals) mechanism / regulation

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

22

Fasting state (between meals) mechanism is regulated by

Glucagon, adrenaline stimulate use of fuel reserve

22

Glycogen serve depleted after how long

1 day

23

RBC cannot use ketones because

They lack mitochondria

24

Starvation after 3 days

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

25

Starvation day 1-3 Blood glucose maintained by

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)

26

What does determine survival time at starvation

Amount of excess stores

27

Cholesterol synthesis rate limiting step is catalyzed by

HMG-CoA reductase

28

HMG-CoA reductase reaction

HMG-CoA to mevalonate

29

HMG-CoA regulation

Insulin+
Thyroxine +
Cholesterol -
Glucagon -