NME 2.29

Question 1

describe the processes involved in lipid metabolism during fed state

Answer 1

• dietary fats are hydrolysed by pancreatic lipase
• short chain fatty acid enter circulation directly
• most fatty acid are re-esterified with glycerol in epithelial cells
• triglyceride enter circulation as chylomicrons
• fatty acid stored as fat in adipose tissue or reesterified to triglycerides in liver and exported as VLDL

Question 2

describe the process of lipid metabolism for fasting state?

Answer 2

• fat in adipose tissue hydrolysed to give glycerol and fatty acids during both fasting and exercise
• fatty acid mobilised and exported to liver and muscles

Question 3

what does the combination of fatty acid and coenzyme A?

Answer 3

acyl-CoA

Question 4

what is carnitine used for?

Answer 4

transport acyl-CoA into mitochondria matrix

Question 5

what inhibits the transport process during fed state?

Answer 5

• malonyl-CoA

Question 6

what process does acyl-CoA undergo in the mitochondria?

Answer 6

• beta-oxidation

Question 7

what are the products of beta oxidation?

Answer 7

• FADH2
• NADH
• acetyl-CoA

Question 8

what is the difference between the beta oxidation in liver and muscle?

Answer 8

• in muscle acetyl CoA oxidise in TCA cycle

- in liver acetyl-CoA converts to ketone bodies

Question 9

what is the function of hormone sensitive lipase?

Answer 9

• catalyse breakdown of triglyceride to fatty acid

Question 10

what activates hormone sensitive lipase?

Answer 10

• adrenaline

- glucagon

Question 11

what inhibits hormone sensitive lipase?

Answer 11

• insulin

Question 12

describe the function of lipoprotein lipase?

Answer 12

• breaks down chylomicrons and VLDL into chylomicrons remnants which release fatty acid and glycerol

Question 13

what is lipoprotein lipase activated by?

Answer 13

apoCII

Question 14

what releases lipoprotein lipase?

Answer 14

endothelial cells in systemic capillaries

Question 15

where is ketone bodies synthesized?

Answer 15

liver mitochondria

Question 16

function of ketone bodies?

Answer 16

energy source for brain and muscle where they are reconverted to acetyl-CoA then oxidise in TCA cycle

Question 17

what is acetoacetate synthesized from?

Answer 17

acetyl CoA

Question 18

what are ketone bodies?

Answer 18

water soluble products of fatty acid beta-oxidation

Question 19

when are ketone bodies synthesized?

Answer 19

when there is high circulating fatty acids and low insulin concentration

Question 20

what does excessive ketone production cause?

Answer 20

metabolic acidosis

Question 21

describe why defects in mitochondrial fatty acid oxidation sometimes manifest as hypoglycaemia?

Answer 21

• defect cause body to be unable to break down adipose stores to provide energy
• body stores of glucose and glycogen will be depleted
• inability to produce glucose from mitochondria fatty acid oxidation cause low glucose levels