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BIOC192 > 36 > Flashcards

36 Flashcards

1
Q

You need to supply your brain with fuels - how much glucose per day?

A

Uses 120 g of glucose per day

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2
Q

What other fuel do other tissues (not brain) need?

A

Fatty acids mainly

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3
Q

We need to conserve _____ as much as possible to maintain ______ and ________

A

Protein
Strucuture
Function

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4
Q

What hormone is mainly involved during survauval while starving

A

glucagon is the main hormone involved - it is produced by pancreas a cells when blood glucose drops

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5
Q

What kind of hormone is glucagon? How many fatty acids?

A

Peptide hormone
29 amino acids

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6
Q

Triacylglycerol stored in adipose tissue amounts to at least…..

A

15kg of fat

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7
Q

Triacylglycerol stores in adipose tissue is enough energy to survive at least ___ days of starvation

A

40

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8
Q

What hormone stimulates lipolyis

A

Glucagon

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9
Q

What is used at fuel in aerobic tissues (except Brian?)

A

Fatty acids (via beta oxidation)

  • not brain, brain used glucose
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10
Q

How much energy per frames of fat?

A
  • 38-40kj
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11
Q

How long can we last without food? - calculation

A
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12
Q
A
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13
Q

Why can’t we just use glycerol to make glucose?

A

Brain needs ~120 g glucose per day
We get around 20 g of glucose from glycerol each day. Where do we get the extra glucose?

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14
Q

How many grams of glycogen in the liver?

A

90-120g

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15
Q

What happens to liver glycogen during starvation?

A

mobilised back to glucose

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16
Q

What hormone is mobilisation of liver glycogen stimulated by?

A

stimulated by the hormone, glucagon

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17
Q

Mobilisation of liver glycogen provides enough glucose for the brain for…

A

1 day

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18
Q

What breaks the 1-4 linkages in glucose

A

Glycogen phosphorylase

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19
Q

what breaks 1-6 linkages in glycogen

A

Debranching enzyme

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20
Q

Debranching enzyme
And Glycogen phosphorylase work together to..

A

Mobiles glucose for metabolism

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21
Q
A
  1. Glycogen phosphorlyse works with attaching an in-organic phosphate group onto a carbon of terminal glucose and cleaves the glycosidic bond between carbon 1 and 4 - producing glucose 1-P
  2. Glucose-1 phosphate is then converted by mutate to glucose-6P
  3. In the liver, NOT in muscle, only liver there is another enzymes called glucose-6-phosphatase

This glucose is for the Brian

22
Q

Gluconeogenesis
- where does it mainly occur?

A

Liver (also kidney cortex)

23
Q

Gluconeogenesis is the synthesis of glucose from:

A

lactate from muscle glycogen
alanine from muscle protein
glycerol from adipose tissue (TAG)

24
Q

What hormone is Gluconeogenesis stimulated by?

A

stimulated by glucagon

25
Q

Gluconeogenesis - what provides the energy required to do this?

A

fatty acid oxidation provides the energy required

26
Q

What is most of the glucose produced from gluconeogeneis used towards?

A

Brain

27
Q

What do lactate, Alanine and glycerol all have in common?

A

All 3 carbons in length
- used in gluconeiogenesis by the liver

28
Q

Can Fatty acids (acetylCoA) be used to make glucose ?

A

Fatty acids (acetylCoA) cannot be used to make glucose B ut can via β-oxidation provide ATP and NADH for gluconeogenesis

29
Q

Big diagram

A

Remember the NADH part

30
Q

Where the liver gets heat it needs to make glucose form (gluconeogeneis)

A
31
Q

Starvation metabolism

A

Burn ca. 200 g of TAG per day; - if we get 40 kJ g -1 then: = 200 x 40 or 8000 kJ per day

The glycerol released corresponds to about 20 g of glucose per day

Brain needs about 120 g of glucose per day

Proteolysis (alanine) to give 100 g of glucose per day corresponds to about 150 g of protein per day — this would deplete muscle reserves to critical in about 2 weeks!

How did James last 43 days?

32
Q

How many kg of protein in our body? Where is it stored?

A

• 10 - 15 kg protein in body
• BUT no specific storage proteins

33
Q

During starvation what happens to some protein?

A

must be degraded to amino acids to make glucose

34
Q

loss of too much protein causes…

A

structural and functional damage

• protein must be conserved as much as possible

35
Q

Protein conservation system in human is specific to only —-

A

Humans

36
Q
A
37
Q

Clinical Research at Harvard — Metabolic Ward

A

Experiment — 6 weeks starvation
New assays had been developed by the Krebb’s lab in Oxford

Obese patient: Ms B 5’ 8’’; 280 pounds (127 kg)

Measured Carotid artery entering and Jugular vein leaving and found 50 g ketone bodies used per day

Hence providing 50% of the brain’s requirement

38
Q
A
39
Q

What are Ketone Bodies synthesised from and where are they synthesised?

A

• synthesised in the liver from fatty acids

40
Q

When are ketone bodies used?

A

• used by starving brain as energy source

41
Q

/

A

Human only adaptation

42
Q

Metabolic adaptations to starvation

A

• fatty acids can be used as a fuel by all aerobic tissues
(except brain); essentially unlimited supply from TAGs
• ketone bodies used by brain
- Therefore, brain needs less glucose; now only about 50 g/day
- Therefore, muscle degradation can slow down (not so many amino acids needed for gluconeogenesis)
- Therefore, body can survive longer

43
Q

Glucose levels in blood over 40 days - Phases of starvation assessed from point of view of glucose metabolism

A
44
Q

How are you able to starve for so long

A

Fuel stores, gluconeogenesis and ketogenesis

45
Q

How does brain continue to function during starvation

A

Ketone bodies, glucose

46
Q

What happens to fat stores during starvation

A

Mobilised to fatty acids and glycerol

47
Q

What happens to muscle during starvation

A

Proteolysis to amino acids

48
Q

Did the energy from the chocolate bar help him survive?

A

About 1 h

49
Q
A
50
Q

Process of ketone body synthesis

A

BIOC192 (38 decks)

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