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1.1 POM Cells > Integration of Metabolism > Flashcards

Integration of Metabolism Flashcards

1
Q

How much of the total body weight is muscle?

A

40%

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2
Q

How much of the total body weight is brain and nervous tissue?

A

2%

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3
Q

How much of the total body weight is adipose tissue?

A

15%

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4
Q

How much of the total body weight is the heart?

A

1%

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5
Q

How much of the total body weight is the liver?

A

2.5%

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6
Q

What is muscle ATP requirement like?

A

High during vigorous contraction

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7
Q

What is brain and nervous tissue ATP requirement like?

A

Continuously high —> 20% BMR

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8
Q

What is the heart’s ATP requirement like?

A

Constant —> 10% BMR

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9
Q

What is the liver’s ATP requirement like?

A

Constantly high —> 20% BMR

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10
Q

Which 2 energy sources do skeletal muscle and the heart rely on?

A
  1. Carbohydrates
  2. Fatty acid oxidation
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11
Q

Which energy source does the brain and nervous tissue rely on?

A
  1. Glucose (needs continuous supply)
    - Ketone bodies can partially substitute
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12
Q

Why can’t the brain metabolise fatty acids?

A

Can’t cross blood-brain barrier

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13
Q

How does hypoglycaemia and hyperglycaemia affect the brain?

A
  • Hypoglycaemia —> faintness/coma
  • Hyperglycaemia —> irreversible damage
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14
Q

What is the source of energy for muscles during light vs vigorous contraction?

A
  • Light —> oxidative phosphorylation
  • Vigorous —> glycogen breakdown and lactate formation (supplies NAD+ for glycolysis)
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15
Q

What type of metabolism is the heart dependant on?

A

Aerobic

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16
Q

What happens to the heart when O2 is limited or energy demand > supply?

A

Cell death —> myocardial infarction

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17
Q

What are the 3 important functions of the liver for metabolism?

A
  1. Interconverts nutrient types
  2. Stores glycogen
  3. Lipoprotein metabolism (for triglyceride and cholesterol tranport)
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18
Q

What should blood glucose levels be maintained at?

A

4.0-5.5 mM

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19
Q

How does the body prevent hypoglycaemia? (3)

A
  1. Glycogenolysis
  2. Release free fatty acids from adipose tissue
  3. Ketone body production from acetyl CoA by the liver
20
Q

Which 3 molecules are important for gluconeogenesis?

A
  1. Lactate —> regenerate pyruvate via LDH
  2. Amino acids —> converted to TCA substrates
  3. Glycerol of triglycerides —> generates DHAP
21
Q

What is the ΔG of gluconeogenesis?

A

-38 kJ/mol

22
Q

Which bonds are needed to make gluconeogenesis energetically favourable and how many are needed?

A

6 Phosphoanhydride bonds

23
Q

What are the 6 steps of gluconeogenesis?

A
  1. Pyruvate —> oxaloacetate
    - Pyruvate carboxylase
  2. —> PEP
    - PEP carboxykinase
  3. —> F16BP
  4. —> F6P
    - F16BPase
  5. —> G6P
  6. —> Glucose
    - G6Pase
24
Q

How many ATPs are used in gluconeogenesis?

A

6

25
Q

Which gluconeogenesis reactions use ATP?

A
  1. Pyruvate —> oxaloacetate -2 ATP
  2. Oxaloacetate —> PEP -2 GTP
  3. PEP —> F16BP -2 ATP
26
Q

What are glucogenic amino acids?

A

Can generate glucose via gluconeogenesis

27
Q

What are ketogenic amino acids?

A

Can generate ketone bodies and fatty acids (via generating acetyl CoA)

28
Q

What 2 things does contracting muscle require?

A
  1. inc ATP
  2. inc Glucose transporters
29
Q

Why is adrenalin secreted during increased muscle contraction?

A
  1. Increases gluconeogenesis in liver
  2. Increases fatty acid release from adipocytes
30
Q

How is lactate involved in sourcing ATP when there is high demand? (2)

A
  1. Lactate synthesis regenerates NAD+ for glycolysis
  2. Lactate used in gluconeogenesis
31
Q

What is The Michaelis Constant?

A

Concentration of of substrate at which enzyme functions at half Vmax

32
Q

What is Km?

A

The Michaelis Constant
(concentration of of substrate at which enzyme functions at half Vmax)

33
Q

What is Vmax?

A

The maximum rate of an enzymatic reaction under saturated substrate conditions

34
Q

Which hexokinase is used in muscle?

A

I

35
Q

Which hexokinase is used in the liver?

A

IV

36
Q

What is the difference between hexokinase activity in muscles vs the liver?

A
  • Muscle HK I low —> control glucose metabolism
  • Liver HK IV high —> high G6P to G
37
Q

What is the difference between the Km of muscles vs the liver?

A
  • Muscle —> 0.1 mM
  • Liver —> 4 mM
    ∴ More substrate needed to reach Vmax for HK IV
38
Q

What is the difference between G-6-P inhibition sensitivity in muscles vs the liver?

A
  • Muscle —> high
  • Liver —> lower
39
Q

When is insulin secreted and why?

A

When glucose levels rise
- Stimulates glucose uptake
- Stimulates glycogen and fat storage

40
Q

When is glycogen secreted and why?

A

When glucose levels fall
- Stimulates gluconeogenesis
- Stimulates glycogen and fat breakdown

41
Q

Which 3 processes is adrenalin important for in metabolism?

A
  1. Glycogenolysis (liver)
  2. Glycolysis (skeletal muscle)
  3. Lipolysis (adipose tissue)
42
Q

Why are glucocorticosteroids important for metabolism?

A

Increase synthesis of metabolic enzymes controlling glucose availability

43
Q

How are blood glucose levels controlled when blood glucose is low? (not consuming glucose)

A
  • Glucagon secretion inc
  • Insulin secretion dec
44
Q

Which 4 metabolites are used during prolonged fasting and how?

A
  1. Fatty acids - released by hydrolysis of triglycerides stored in adipose tissue
  2. Amino acids - provide substrates for gluconeogenesis
  3. Ketone bodies - can partially substitute brain’s glucose requirements
  4. TCA intermediates - for gluconeogenesis
45
Q

What is Type 1 diabetes?

A

Failure to secrete sufficient insulin (B-cell dysfunction)

46
Q

What is Type 2 diabetes?

A

Failure to respond appropriately to insulin (insulin resistance)

47
Q

What are the 4 complications of diabetes?

A
  1. Hypoglycaemia
  2. Hyperglycaemia
  3. Cardiovascular issues
  4. Ketoacidosis

1.1 POM Cells (15 decks)

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