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Fundamentals Of The Living Cell > Integration of whole body metabolism > Flashcards

Integration of whole body metabolism Flashcards

1
Q

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

A

Uses 100-120g of glucose daily

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2
Q

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

A

Half the energy is used for Na-K transports to maintain membrane potential and synthesis of neurotransmitter

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3
Q

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

A

Lacks energy stores so glucose is transported by GLUT3 which 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

Dangerous when 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 but 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 for of what?

A

Acts as a reservoir of metabolic energy in the form of triglycerides

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10
Q

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

A

If 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

During starvation, 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 dependant on?

A

Glucose uptake by GLUT-4 is insulin dependant

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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 and 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 plateaux at 20 day?

A

Βeta hydroxybutyrate plateaux 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 and form 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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