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Physiology II Test II - Jourdan > Energy Balance and Metabolism I > Flashcards

Energy Balance and Metabolism I Flashcards

1
Q

To produce energy, what is metabolized?

A

Proteins, carbohydrates and fats are oxidized to form ATP

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2
Q

ΔG° = std free energy difference which is the difference in what?

A

Difference in free energy when 1 mole of each reactant is converted to 1 mole of each product at 1 atm pressure at 25°C

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3
Q

-ΔG° =

A

Exergonic reation

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4
Q

+ΔG° =

A

Endergonic reaction

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5
Q

ATP -> ADP + Pi

ΔG° = ?

A
  • 7300 cal/mole

- 12000 cal/mole

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6
Q

What becomes the final common pathway for the transport of almost all the carbohydrates to the tissue cells?

A

Glucose

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7
Q

What sugars are all interconvertible?

A

Galactose, glucose, and fuctose (all hexoses)

Each can be phosphorylated

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8
Q

What sugars can be converted to fuctose-6-phosphate and enter the glycolytic pathway?

A

Galactose and glucose

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9
Q

Transport of glucose into tissue cells is via what?

A

Active sodium-glucose co-transport
-Active transport of sodium provides energy for absorbing glucose against concentration gradient

Via facilitated transport
-only transported from higher to lower concentrations

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10
Q

What increased glucose transport x10?

A

insulin

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11
Q

What prevents diffusion of glucose out of the cell?

A

Phosphorylation

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12
Q

Where can phosphorylation of glucose be reversed?

A

In liver, renal, and intestinal cells

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13
Q

What are the roles of the following enzymes?
Glucokinase
Phosphatase
Phosphorylase

A

Blood glucose to glucose 6 phosphate
Glucose 6 phosphate to blood glucose
Glycogen to Glucose 1 phosphate

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14
Q

What are factors that can activate phosphorylase?

A

Epinephrine (from adrenal medulla)

Glucagon (from alpha cells of pancreas)

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15
Q

What are the effects of phosphorylase?

A

Promotes conversion of glycogen to glucose

Glucose can then be released into blood

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16
Q

What are the end products of glycolysis?

A

Pyruvic acid (2)
Hydrogens (4): release is catalyzed by dehydrogenase
ATP (2): 2 where needed at the beginning so 4 is total and net is 2

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17
Q

What are the end products of pyruvic acid -> Acetyl-CoA?

A

Acetyl-CoA (2)
Hydrogens (4): release is catalyzed by dehydrogenase
Carbon dioxide (2)

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18
Q

Where does the citric acid cycle occur?

A

Mitochondrial matrix

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19
Q

What are the end products of citric acid cycle?

A

Hydrogens (16): release by dehydrogenase
ATP(2)
Carbond dioxide (4)

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20
Q

What is the net reaction (excluding glycolysis) of the citric acid cycle?

A

2 Acetyl-CoA + 6 H2O + 2 ADP -> 4 CO2 + 16 H + 2 ATP

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21
Q

Where does oxidative phosphorylation take place?

A

Mitochondrial cristae

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22
Q

What is the fate of hydrogen atoms from cycles previous to oxidative phosphorylation?

A
  1. Hydrogens are removed in pairs
  2. One member of each pair becomes a hydrogen ion
  3. The other combines with NAD+->NADH
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23
Q

What is the fate of electrons removed from hydrogen ions?

A

They enter the electron transport chain

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24
Q

What are the major components of the electron transport chain?

A

Flavoprotein
Several iron sulfide proteins
Ubiquinone (Q)
Cytochrome A3 (cytochrome oxidase)

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25
Q

Where is Cytochrome A3 located? What role does it play?

A

Located on inner membrane

Can give up two electrons to oxygen

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26
Q

Describe the cheiosmotic mechanism part I

A

Electrons pass through chain: release large energy
Energy used to pump hydrogen ions from inner matrix into outer chamber between inner and outer membranes
High concentration of H+ in chamber
Strong negative potential created in inner matrix

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27
Q

Describe the cheiosmotic mechanism part II

A

H+ ions flow from high to low through ATP synthetase
Energy derived from H+ flow converts ADP to ATP
For each 2 electrons that pass through electron transport chain, up to 3 ATP molecules are synthesized

**note that the 2 pairs of hydrogens derived from citric acid cycle enter the ECC at a later point and provide energy for 2 ATP molecules per pair

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28
Q

In summary of oxidative phosphorylation,the number of ATPs formed per glucose molecule = ?

A

2 ATPs from glycolysis
2 ATPs from citric acid cycle
34 ATPs from oxidative phosphorylation

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29
Q

What is the maximum number of ATPs per glucose molecule ?

A

38

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30
Q

How many calories produced per mole of glucose?

A

38 x 12,000 cal/mole = 456,000

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31
Q

efficiency of calories/mole of glucose =

A

456,000/686,000 = 66% efficiency

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32
Q

What is the pentose phosphate pathway?

A

A cyclical pathway in which one molecule of glucose is metabolized for each revolution of the cycle

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33
Q

For every six molecules of glucose that enter the PPP, how many molecules of glucose are resynthesized?

A

five

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34
Q

What is the PPP mostly used for?

A

The synthesis of fats and other substances

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35
Q

Hydrogens generated from the PPP are bound to what?

A

NADP+ instead of NAD+

36
Q

What is NADP+ used for?

A

Used in the synthesis of fats from carbohydrates

37
Q

In the liver what is broken down by the PPP?

A

glucose is broken down producing excess NADPH

38
Q

What does NAPDH participate in?

A

The conversion of Acetyl-CoA into fatty acid chains

39
Q

Glucose is preferentially stored as what?

A

Glycogen until the storage cells (liver and muscle) are saturated

40
Q

What happens to excess glucose?

A

Converted into fat (liver and fat cells) and stored in fat cells

41
Q

Most triglycerides are digested into what?

A

Monoglycerides and fatty acids

42
Q

Intestinal epithelial cells resynthesize monoglycerides and fatty acids into what?

A

Triglycerides that enter the lymph as chylomicrons

43
Q

What is absorbed to the chylocmicron surfaces?

A

Apoprotein B

44
Q

Chylomicrons are transported to the venous system via what?

A

the thoracic duct

45
Q

Chylomicrons are removed from the blood by various tissues, especially:

A

Adipose tissue
Skeletal muscle
Heart

46
Q

Adipose tissue, skeletal muscle and heart synthesize lipoprotein lipase which:

A

Is transported to surface of capillary epithelial cells

Hydrolyzes chylomicron triglycerides, releasing fatty acids and glycerol

47
Q

Fatty acids can be used as what?

A

Fuel or again synthesized into triglycerides

48
Q

How much of the plasma fatty acid is replaced every 2-3 minutes?

A

50%

49
Q

All normal energy requirements of the body can be provided by what?

A

The oxidation of fatty acids without using carbohydrates or proteins as an energy source

50
Q

What conditions increase the utilization of fat for energy?

A

Starvation

Diabetes mellitus

51
Q

Lipoproteins synthesized by intestinal cells are:

A

Chylomicrons

52
Q

Liporoteins synthesized by the liver are:

A

Very low density L VLDLs
Intermediate density L IDLs
Low density L LDLs
High density L HDLs

53
Q

Lipoproteins transport what in the blood?

A

Lipids

54
Q

Describe VLDLs

A

High concentrations of triglycerides and moderate amounts of cholesterol and phospholipids
Transport lipids mainly from liver to adipose tissue

55
Q

Describe LDLs

A

High concentration of cholesterol and moderate concentration of phospholipids

56
Q

Describe HDLs

A

High concentration of proteins and low concentration of cholesterol and fatty acids

57
Q

What are the principal functions of the liver in lipid metabolism?

A

?

58
Q

Under what conditions do large quantities of triglycerides appear in the liver?

A

?

59
Q

Trigylcerides are hydrolyzed into what?

A

Fatty acids and glycerol which are transported in blood to tissues

60
Q

Almost all cells use fatty acids for energy except:

A

Brain cells and red blood cells

61
Q

What is glycerol converted to?

A

Glycerol-3-phosphate

62
Q

Fatty acids are converted to what in the mitochondria?

What process is used?

A

Acetyl-CoA

Beta oxidation

63
Q

What is used as a carrier molecule into the mitochondria?

A

Carnitine

64
Q

Acetyl-CoA enters the citric acid cycle by binding to what?

A

Oxaloacetic acid

65
Q

Hydrogens enter the ________ oxidative system

A

Chemiosmotic

66
Q

Products from beta-oxidation of one molecule of stearic acid:

A

9 aceytl-CoA molecules

146 molecules of ATP

67
Q

Degradation of fatty acids in the liver releases what?

A

Many acetyl-CoA not sued for metabolism

68
Q

2 acetyl-CoAs condense to form what?

A

Acetoactic acid

69
Q

Some of the acetoacetic acid is converted to:

A

B-hydroxybutryic acid

acetone

70
Q

Acetoacetic acid, β-hydroxybutryic acid, and acetone are all examples of what? They all diffuse back into cells and are converted to what?

A

ketone bodies

Acetyl CoA

71
Q

If concentration of ketone bodies increase above normal blood what occurs?

A

Ketosis occurs

72
Q

What are conditions favoring ketosis?

A

Starvation
Diabetes
Diet composed almost entirely of fat

73
Q

Synthesis of fatty acids is a 2 step process that involves what?

A

Malonyl-CoA and NADPH

74
Q

What is the importance of fat synthesis?

A

M0re fat can be stored in tissues than carbohydrates

Weight-for-weight, fat contains about 2.5x the energy of carbohydrates

75
Q

Why are fats poorly synthesized during insulin insufficiency?

A

?

76
Q

Why are carbohydrates preferred over fats for energy?

A

?

77
Q

Describe the development of atherosclerotic plaque

A

Damage to vascular endothelium
Circulating monocytes and LDLs accumulate at injury site
Monocytes become macrophages
Fatty streaks form
Surrounding fibrous and smooth muscle tissues form large plaques

78
Q

What does damage to vascular endothelium cause?

A

Increases the expression of adhesion molecules

Decreases release of NO and other substances that prevent adhesion of macromolecules and cells

79
Q

How do monocytes enter the injury site in the process of atherosclerotic plaque development?

A

Cross endothelium
Enter intima
And become macrophages

80
Q

What do macrophages do in the process of atherosclerotic plaque development?

A

Ingest lipoproteins
become foam cells
Form visible fatty streaks

81
Q

What happens to the fatty streaks in the process of atherosclerotic plaque development

A

Grow larger and coalesce

82
Q

Surrounding fibrous and smooth muscle tissues in the process of atherosclerotic plaque development go on to form what?

A

They proliferate and form large plaques

83
Q

Large plaques may occlude what?

A

lumen

84
Q

Large plaques may become what?

A

Sclerotic or fibrotic and may become calcified

85
Q

What are the basic causes of atherosclerosis?

A 
Increased LDLs 
Familial hypercholesterolemia (Defective LDL receptors)
86
Q

What lipoprotein may be able to absorb cholesterol crystals that are beginning to be deposited in arterial walls?

A

HDLs

Physiology II Test II - Jourdan (6 decks)

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