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Fundamentals of the Living Cell > Integration of Full Body Metabolism > Flashcards

Integration of Full Body Metabolism Flashcards

1
Q

how many grams of glucose does the brain use per day?

A

100-120g

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2
Q

what is half the energy supplied to the brain used for?

A

→Na-K transports to maintain membrane potential

→ synthesis of neurotransmitter

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3
Q

What does the brain lack and how is glucose transported in cardiac muscle?
Comment on the km of the transporter

A

→ Lacks energy stores
→ glucose is transported by GLUT3
→ has a low Km
→ meaning the transporter is active at most times

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4
Q

At what level of glucose is it deemed dangerous?

A

→ glucose levels drop below 2.2mM.

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5
Q

What are fatty acids usually used for and not usually used for?

A

→ Fatty acids not usually used for energy

→ used for membrane biosynthesis

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6
Q

comment on the glycogen stores in cardiac muscle

A

Little or no glycogen stores

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7
Q

what is the main energy source for cardiac muscle and what is that followed by?

A

→Fatty acid main source of energy

→followed by lactate and ketone bodies.

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8
Q

what is adipose tissue a store for?

A

Store for fatty acids

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9
Q

What do adipose tissue act as and in the form of what?

A

→ reservoir of metabolic energy

→ form of triglycerides

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10
Q

What are fatty acids synthesised by when a person is starved?

A

→person starved, FA synthesised by chylomicrons

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11
Q

How is glucose transported in adipose tissue?

A

Glucose is transported by GLUT 4

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12
Q

What is GLUT 4 sensitive to?

A

GLUT 4 is insulin sensitive

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13
Q

What do kidneys produce and how many times a day is it filtered?

A

Produces urine and plasma is filtered up to 60 times a day

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14
Q

Why is only a small volume of urine produced?

A

Only small volume of urine produced because water soluble material is largely reabsorbed to prevent loss

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15
Q

What do kidneys contribute during starvation?

A

kidney may contribute half of the blood glucose through gluconeogenesis

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16
Q

What does the liver regulate?

A

Regulates metabolism: carbs, fatty acids and amino acids

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17
Q

Where do most compounds absorbed by the gut pass through?

A

Most compounds absorbed by gut pass through the liver

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18
Q

What does the liver provide?

A

Provides fuel for brain muscle and other peripheral organs

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19
Q

Where does the liver take its energy from?

A

alpha ketoacids

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20
Q

What is glucose absorbed by hepatocytes used for more than the other?

A

→glucose absorbed by hepatocytes used for production of fat synthesis
→ more than the production of energy

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21
Q

How is blood glucose controlled by liver metabolism?

A

→glucose transported into hepatocytes by GLUT2 and immediately phosphorylated by glucokinase

→G6P from glycogen breakdown converted to glucose by the action of G6P and transported out the cell into the blood by GLUT-2

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22
Q

What is GLUT2 not sensitive to?

A

GLUT-2 is not insulin sensitive

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23
Q

What is GLUT2 driven by?

A

GLUT2 is driven by concentration gradient and is a means of regulating low blood glucose levels

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24
Q

what is glucose uptake by GLUT4 in muscles dependent on?

A

Glucose uptake by GLUT-4 is insulin dependent

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25
Q

what is glucose converted by into G6P in muscles?

A

Glucose converted to G6P by hexokinase

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26
Q

comment on the free glucose concentration in muscle cells

A

low free glucose concentration in cell

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27
Q

How is glucose mobilised in muscles during exercise?

A

Glucose is mobilised from glycogen in exercise

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28
Q

What is a rapid source of ATP in muscle cells?

A

Glycolysis of the G6P is a rapid source of ATP

29
Q

What does ATP directly power?

A

ATP directly powers myosin

30
Q

What are the sources of energy in 100m sprint?

A 
→ATP stores 
→ Glycolysis 
→Glycogen stores 
→Creatine phosphate 
-Small store of ATP
31
Q

How many seconds of reserve does creatine phosphate provide?

A

5-6 seconds

32
Q

What does anaerobic breakdown of glycogen stores give and the effect on pH?

A

Anaerobic respiration gives lactate and a fall in pH

33
Q

How many moles of ATP required roughly in a marathon?

A

150 moles of ATP needed

34
Q

How many moles will body glycogen provide in a marathon?

A

Body glycogen will provide only 103 moles

35
Q

What type of respiration is more efficient in marathons?

A

Aerobic respiration more efficient in marathons

36
Q

What cooperation is required in marathons and why?

A

→Co-operation between muscle, liver and adipose tissue required
→Because ATP required exceeds that stored by muscles

37
Q

What is a large source of ATP and comment on the metabolism of this source compared to others?

A

→Fats are a large source of ATP, metabolism even slower than glycogen
→x10 slower than creatine phosphate

38
Q

What is energy sources are more efficient to use in marathons?

A

More efficient to use both fat and glycogen

39
Q

How much glycogen is left at the end of a marathon?

A

At end of marathon, 1/2 glycogen left

40
Q

What are the interactions between the liver and muscle during exercise?

A

→During exercise, glycolysis exceeds the capacity of TCA,

→pyruvate converted to lactate in muscles and transported to livers cori cycle

41
Q

What happens to muscle proteins during exercise and the interactions between liver and muscle?

A

→Muscle protein also broken down into amino acids
→majority is converted to alanine and transported to liver.
→Used for gluconeogenesis

42
Q

What happens to amino acids in a fed state?

A

Amino acids used for protein synthesis

43
Q

What happens to excess amino acids in a fed state?

A

Made into keto acids

44
Q

In a fed state, where are fats delivered and with the aid of what?

A

Fats also delivered to muscle via the aid of VLDLs

45
Q

What do resting muscles use in a fed state?

A

Resting muscle use FA as source of energy

46
Q

What is excess glucose stored as in adipocytes and muscles in a fed state?

A

Excess glucose stored as FA in adipocytes or as glycogen in muscle

47
Q

What happens to blood glucose, insulin levels and glucagon levels in post absorptive phase?

A

Blood glucose falls, insulin level falls and glucagon levels rise

48
Q

Activity of what enzyme increases in post absorptive phase as well as what breakdown?

A

Phosphorylase a activity increases as does glycogen breakdown

49
Q

In post absorptive phase, what does a drop in insulin do?

A

Drop in insulin reduces glucose uptake by muscle and adipose tissue

50
Q

In early starvation(4-24hrs), where is glucose released from and due to what reason?

A

Glucose released from liver due to gluconeogenesis and glycogenolysis

51
Q

In early starvation, what is there a mobilisation of?

A

Mobilisation of FA from adipose tissue

52
Q

What happens to the glucose use in early starvation and due to what reason?

A

Glucose use falls as muscle switches to FA oxidation

53
Q

What does insulin drop cause in early starvation?

A

Insulin drops causing GLUT4 expression by muscle to fall reducing glucose uptake

54
Q

What happens after 12 hrs of starvation in terms of percentage of energy?

A

After 12hrs 45% of resting energy from FA and 40% from glucose

55
Q

What happens to glycogen stores after intermediate starvation(1-20 days)?

A

Glycogen stores almost completely depleted

56
Q

What process increase is there in intermediate starvation?

A

Increased lipolysis and ketogenesis and gluconeogenesis

57
Q

Why is there an increase in gluconeogenesis in intermediate starvation?

A

Increased gluconeogenesis to maintain blood glucose

58
Q

What does 60hrs of FA account for?

A

60hrs FA account for 3/4 energy provision

59
Q

What happens after 8 days in intermediate starvation?

A

After 8 days, beta-hydroxybutyrate is raised 50 fold

60
Q

What do you see in further starvation?

A

Further starvation sees kidney take over gluconeogenesis from liver

61
Q

In prolonged starvation(>3weeks)what plateaus at 20 day?

A

Βeta hydroxybutyrate plateaus at 20 days

62
Q

In prolonged starvation, what does the brain start to use and what amount of glucose needed in grams falls to?

A

As brain starts to move to using ketone bodies, the need for glucose falls from 100g to 40g/day

63
Q

What other sources are there for gluconeogenic precursors?

A

Other sources of gluconeogenic precursors are lactate and glycerol

64
Q

What is lactate recycled by in prolonged starvation?

A

Lactate recycled by the cori cycle

65
Q

What is oxidised in prolonged starvation?

A

Glycerol and amino acids are oxidized

66
Q

What are the proteins? from what precursors in prolonged starvation?

A

Proteins are broken down muscle forming amino acid precursors

67
Q

How else is alanine formed in skeletal muscles?

A

Alanine also formed by transamination of pyruvate

68
Q

What happens to the alanine formed in skeletal muscles?

A

released into blood where it is taken up by liver and converted to glucose

69
Q

Why does the liver release pyruvate from alanine?

A

Because muscle can use amino acids for carbon skeleton but cannot form urea therefore the liver removes nitrogen and release pyruvate

Fundamentals of the Living Cell (31 decks)

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