Exercise and starvation

Question 1

What does creatine/phosphocreatine act as a source for for the heart and muscles?

Answer 1

• Source of phosphate groups
• Can donate to ADP -> ATP
• Reserve when ATP falls rapidly in exercise

Question 2

What enzyme converts creatine to phsophocreatine?

Answer 2

Creatine kinase

Question 3

What can creatine kinase be an important biomarker for identifying?

Answer 3

MI

Question 4

What is creatinine?

Answer 4

Spontenously converesed from creatine

Question 5

What is the amount of creatinine proportional to?

Answer 5

Muscle mass

Question 6

What is creatinine excreted by?

Answer 6

Kidneys

Question 7

When is ATP and creatinine consumed (what period of time)?

Answer 7

Within seconds of exercise

• Used for short intense exertion
• > Heavy lifting
• > Sprinting

Question 8

Why does intensity of exercise diminish over time?`

Answer 8

Creatinine and ATP are consumed rapidly

- Other pathways are required for longer exercise (which have a slower metabolism)

Question 9

What does calcium (released from muscles) activate (what pathways)?

Answer 9

• Glycogenolysis

- TCA cycle

Question 10

What do Glucagon and epinephrine inhibit to stop fatty acid synthesis?

This occurs in intense aerobic exercise

Answer 10

Inhibit Acetyl-CoA Carboxylase (rate limiting step of fatty acid synthesis)

Acetyl CoA + CO2 -> Malonyl-CoA

Question 11

What process does Malonyl-CoA inhibit?

Answer 11

B-oxidation

Question 12

What vitamin is a cofactor for Acetyl-CoA carboxylase?

Answer 12

Biotin

Question 13

Levels of what molecule fall in intense aerobic exercise, signalling a drop in fattyacid synthesis?

Answer 13

Malonyl-CoA

Question 14

What molecule inhibits Carnitine Palmitoyl Transferase-1?

Answer 14

Malonyl-CoA

• Less fatty acid degraded

Question 15

What molecule is consumed in exercise which subsequently leads to muscle cramps?

Answer 15

NAD+ consumed

• NAD+ generated in Pyruvate to lactate conversion
• Increased lactate causes low pH and cramps

Question 16

What organelle is more abundant in the muscles of distance runners?

Answer 16

Mitochondria

Question 17

The presence of what chemical will cause NAD levels to increase (NADH to decrease)?

Answer 17

O2

- NADH can be converted to NAD in the ETC

Question 18

What are the effects of insulin?

Answer 18

• Glycogen synthesis
• Increases glycolysis
• Inhibits gluconeogenesis
• Promotes glucose -> adipose tissue (used to form triglycerides)
• Promotes uptake of amino acids by muscle
• Stimulates protein synthesis / inhibits breakdown

Question 19

What enzyme found in the liver and pancreas is induced by insulin?

Answer 19

Glucokinase (Glu -> G6P)

- ATP -> ADP

Question 20

What enzyme does insulin stimulate?

In regards to glucose/glycogen levels

Answer 20

Glycogen synthase

Question 21

What enzyme does glucagon (+epinephrine) stimulate?

In regards to glucose/glycogen levels

Answer 21

Glycogen phsophorylase (breaks down glycogen)

Question 22

What molecules/hormones stimulate acetyl-CoA carboxylase (fatty acid synthesis)?

Answer 22

• Insulin

- Citrate

Question 23

What are the effects of glucagon?

Answer 23

• Glycogen breakdown in liver
• Inhibits fatty acid synthesis
• Stimulates release of fatty acids from adipose tissue
• Stimulates gluconeogenesis

Question 24

After how much time fasting will glycogen stores be exhausted roughly?

Answer 24

~ 24 hours

Question 25

What is glutamate and pyruvate converted into in the alanine cycle in muscles?

Answer 25

- Alanine | - alpha-KG

Question 26

What substance does Glutmate require in the muscle cells to undergo the alanine cycle?

Answer 26

NH4+

Question 27

Where does alanine travel to to create glutamate and pyruvate?

Answer 27

The liver | - Also requires a-KG

Question 28

What is glutamate converted into in the liver?

Answer 28

NH4+

Question 29

Where does the pyruvate and subsequently glucose travel to to renter the alanine cycle?

Answer 29

Muscle tissue

Question 30

What molecule is involved in the cori cycle?

Answer 30

Lactate

Question 31

What 2 cycles maintain plasma blood sugar levels during starvation?

Answer 31

- Cori cycle - Lactate | - Alanine cycle

Question 32

Describe the steps involved in glycerol becoming Dihydroxyacetone Phosphate?

Answer 32

Glycerol | - > Glycerol-3-Phosphate (enzyme: Glycerol Kinase - > Dihydroxyacetone Phosphate enzyme: G-3-P Dehydrogenase)

Question 33

What is the 3-carbon fatty acid that B-oxidation stops at?

Answer 33

Propionyl-CoA

Question 34

What is propionyl-CoA converted into to join the TCA cycle?

Answer 34

Succinyl-CoA

Question 35

What enzyme converts propionyl-CoA (3C FA) to Succinyl-CoA (TCA cycle or gluconeogenesis)?

Answer 35

Propionyl-CoA Carboxylase

Question 36

What vitamin acts as a cofactor for Propionyl-CoA carboxylase?

Answer 36

Biotin

Question 37

What causes oedema in Kwashiorkor?

Answer 37

Inadequate protein intake | - Hypoalbuminemia -> oedema

Question 38

What is the other malnutrition disease that has normal protein but insufficient total calories?

Answer 38

Marasmus - Muscle and fat wasting - No oedema

Question 39

Hypoglycemia and ketosis in a child, after an overnight fast is can be due to what group of diseases?

Answer 39

Glycogen storage diseases

Question 40

What enzyme is deficient in hereditray fructose intolerance?

Answer 40

- Aldolase B

Question 41

When does hereditray fructose intolerance usually present?

Answer 41

After weaning from breast milk

Question 42

What is depleted and what can build-up in hereditray fructose intolerance?

Answer 42

- F1P builds up - ATP depletes - Glucose depleted

Question 43

Disorders of what organelle create hypoketotic hypoglycemias?

Answer 43

Mitochondrial disorders

Question 44

Explain how a disorder in the mitochondria can create a hypoketotic hypoglycemia?

Answer 44

- Loss of B-oxidation and gluconeogensis - FFA -> B-oxidation -> ketones (B-oxidation), cannot happen as mitochondria not functional - First step of gluconeogensis is pyruvate -> oxaloacetate, occurs in mitochondria also - Leads to hypoglycemia

Question 45

What are 2 disorders which cause hypoketotic hypoglycemia?

Answer 45

- Carnitine deficiency | - MCAS deficiecy

Question 46

What are the findings in carnitine deficiency?

Answer 46

- Hypoketosis - Hypoglycemia - Low serum carnitine - Low serum acylcarnitine

Question 47

What are the findings in MCAD deficiency?

Answer 47

- Hypoketotic hypoglycemia - Medium chain acyl-CoA dehydrogenase - Dicarboxylic acids 6-10 carbons in urine - High acylcarnitine levels