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Lecture 1 Flashcards

1
Q

Energy currency

A

ATP

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2
Q

ATP production ___ during exercise

A

increases

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3
Q

ATP has:
1.
2.
3.
energy systems

A
  1. Immediate
  2. Short term
  3. Long-term
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4
Q

Anaerobic metabolism

A

does NOT requite oxygen for the release of energy from fuels

  1. ATP-CP system
    * 2. Glycolysis (glucose → pyruvate)*
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5
Q

Sources of muscle glucose for glycolytic metabolism

A
  1. blood glucose from exogenous source
  2. glycogen (from muscle)
  3. blood glucose from liver glycogen
  4. ⇣ All go to: glycolytic sequence (ADP + Pi → ATP)
    1. Pyruvic acid in slow glycolysis
    2. Lactic acid in fast glycolysis
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6
Q

Energy release from carbs

A

Glucose: 36ATP

Avg carbohydrate = 4.2kcal/gm

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7
Q

Energy release from fats

A

146 ATP

trigylcerides: 457 ATP

average lipid 9.4kcal/gm

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8
Q

Energy release from proteins

A

average protein = 5.65 kcal/gm

in the body: 4.6kcal/gm (due to loss of H+ by urea)

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9
Q

Glycolysis occurs in the:

A

cytosol

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10
Q

Hexokinase & glycolysis

A

Hexokinase traps glucose in the cell by adding a phosphate group

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11
Q

Phosphofructokinase (PFK)

A

Rate-limiting enzyme for glycolysis which is under regulatory control

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12
Q

Glycolysis generates ATP very (fast/slow) without a requirement for ___ - but limited amounts are produced ( __ ATP per glucose)

A

Fast

no requirement for O2

limited amount - 2ATP/glucose

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13
Q

Glycolysis is an extremely important source of ATP especially at the ___ of exercise & when exercise is: __

or when:

A
  • onset of exercise (first 90s)
  • intense exercise
  • at maximal levels of exercise when demand for O2 outstrips deliver to the muscle cell

Example: exercise in patients with chronic CV or respiratory diseases

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14
Q

Small amounts of lactic acid are formed ___ in tissues and red blood cells

A

continuously

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15
Q

Accumulation of lactate in the blood means that production >> ___

A

production>>utilization by other tissues

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16
Q

Lactate can be metabolized by other cells for:

A

-energy (liver, heart, muscle)

or used for gluconeogenesis in the liver

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17
Q

Accumulation of blood lactate is associated with

A

significant levels of anerobic metabolism

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18
Q

formation of lactic acid (diagram)

A
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19
Q

Aerobic Metabolism

A

Requires oxygen for the release of energy from fuels

  • Krebs cycle oxidizes carb, fat, & protein breakdown products - liberate electrons (H+)*
  • O2 drives oxidative phosphorylation - the production of ATP from electrons*
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20
Q

Krebs Cycle is part of ___ metabolism

A

aerobic

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21
Q

Krebs cycle is the intersection of:

A

carbohydrate, fat, and protein catabolism

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22
Q

(Krebs Cycle) carbohydrates, fats, and some amino acids provide:

A

acetyl-CoA

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23
Q

(Krebs Cycle) proteins provide mostly

A

pyruvate (and other Krebs cycle intermediates)

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24
Q

Krebs cycle produces

A

FADH and NADH → used by electron transport chain to produce ATP

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25
Q

Metabolic Mill

A

describes the Krebs cycle as the convergence point for a carbohydrate, fat, and protein catabolism

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26
Q

Lipids burn in a:

A

carbohydrate flame

-pyruvate supplies oxaloacetate (an acceptor for Acetyl-CoA)

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27
Q

If the rate of glycolysis is too slow for the amount of lipid breakdown =

A

build-up of excessive Acetyl-CoA and FFA build up in the plasma → ketone body formation by the liver (diabetic ketoacidosis)

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28
Q

Acetyl-CoA is the ___ to the Krebs Cycle

A

entry point

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29
Q

Amino acids can enter the krebs cycle at __ points

A

several

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30
Q

Excess glucose can be stored as

31
Q

excess protein can be stored as (and also used as)

A
  1. fat
  2. Protein can be used to by the liver to make glucose (gluconeogenesis)
32
Q

Excess fat & glucose

A

excess fat cannot be used to make glucose

33
Q

Excess fat & the liver

A

in the liver, the glycerol derived from the breakdown of triglycerides can be used as the backbone for synthesis of glucose.

ONLY PROVIDES A SMALL AMOUNT OF GLUCOSE

34
Q

Carbohydrate (CHO) functions in the body

A
  1. Fuel for CNS and red blood cells
  2. Energy source during activity
  3. Helps preserve tissue protein
  4. Serve as a primer for fat metabolism
35
Q

Most of the time, CNS uses __ for energy exclusively

36
Q

Under chronic low carbohydrate conditions, like ketoacidosis or starvation (hypoglycemia), the CNS can adapt over time and metabolize ___ for energy.

37
Q

symptoms of hypoglycemia

A

weakness

hunger

dizziness

profound hypoglycemia can cause unconsiousness and irreversible brain damage

38
Q

Relationship between glycogen stores and fatigue

39
Q

Pre-exercise muscle glycogen depletion impairs vigorous exercise capacity

40
Q

Moderately Heavy Exercise (70% VO2 Max): note reliance on blood glucose and glycogen stores decline

41
Q

Glucose as an energy source during activity

Glycogen in liver and muscle can be broken down into

42
Q

Glucose as an energy source during activity

Muscle glycogen stores can be depleted after:

A

several hours → causing fatigue

43
Q

Glucose as an energy source during activity

Blood glucose is also taken up by ___ which increases with __ intensity

A

active muscle

uptake increases with exercise intensity

44
Q

Glucose as an energy source during activity

As muscle glycogen stores decline there is an increasing reliance on ___ as the source of carbohydrate

A

blood glucose

45
Q

Carbohydrate supplementation during prolonged exercise can ___ fatigue

A

delay

  • Carb intake is 1g/min or drinking 240mL (8oz) of a 5% carbohydrate solution every 15 mins*
  • Absorption from GI tract = limiting factor → igestion should take place early in the prolonged exercise (within first 90 mins) so carbohydrates are available during the latter stages of exercise*
46
Q

“Hitting the wall”

A

Correlation between low levels of muscle glycogen and fatigue

47
Q

Relationship between glycogen stores and fatigue

A
  1. muscle glycogen plays a role as a primer for lipid metabolism
  2. rate of energy production is slower from lipids than from glycolysis
  3. RESULT: slow ATP production and increasing cellular acidosis -→ promote fatigue
48
Q

Role of lipids in the body

A
  1. Energy source and storage
  2. Protection of Vital Organs (padding)
  3. Thermal insulation (subcutaneous fat)
    1. protective during prolonged cold exposure
    2. Hinders thermoregulation during heat stress
  4. Vitamin carrier and hunger supressor
49
Q

Fatty acids are stored as ____ in ___ and to a limited extent in ___

A

stored as: trigylcerides

in: adipocytes and limited extent in muscle cells

50
Q

fatty acids are liberated from triglycerides and enter ____ in ____

A

enter: beta-oxidation
in: mitochondria

51
Q

Beta-oxidation produces ___ for electron transport chain and ____ for Krebs Cycle

A

H+ for electron transport chain

and acetyl CoA for Krebs Cycle

52
Q

At rest, lipids provide ___% of energy

53
Q

the proportion of energy supplied by lipids increases with

A

duration of exercise

54
Q

proportion of energy suppled by lipid also depends on

A

intensity of exerucse

55
Q

At ___ to ___ intensity, the greatest % of energy requirements during steady state exercise is derived from lipids

A

light to moderate (60-70% VO2 Max)

At very heavy exercise intensities (e.g. >80% VO2 max) lipid oxidation drops off considerably → extra demand for ATP with heavy intensity is supplied by glucose

56
Q

***With higher intensity exercises, a reduction in the % of energy derived from fat doesn’t necessarily mean that the amount of fat burned goes down as well

57
Q

Lipids as an energy source after training

Training adaptations increase the ability to use ___ as an energy source especially those mobilized from

A

increase the ability to use fat as an energy source; especially those mobilized from muscle trigylceride stores

58
Q

Lipids as an energy source after training

Absolute rates of fat oxidation during submax exercise are higher after

A

aerobic exercise training

59
Q

Lipids as an energy source after training

Factors that contribute to increased endurance after exercise training

A
  1. Conserving limited glycogen stores
  2. enhanced lipid oxidation
60
Q

Sources of proteins

A

plasma, muscle, visceral tissue

61
Q

At rest __% of energy is supplied by protein catabolism

62
Q

Certain amino acids can be used for:

A
  1. Gluconeogenesis
  2. Energy source (Krebs Cycle)
  3. Fat synthesis (they can be a source of acetyl-CoA, the building block for fat)
63
Q

Proteins produce ___ (as well as other Kreb Cycle intermediates)

A

Acetyl-CoA

64
Q

Protein and ATP during exercise

A

protein is not a major source of ATP during exercise in a well-nourished individual

65
Q

branched chain amino acids & ATP during exercise

A

branch chain amino acids can be oxidized by skeletal muscle and thus can supply ATP

66
Q

Lack of CHO or lipid for metabolism results in a large increase in

A

protein catabolism

67
Q

protein use for energy greatly increases when subjects exercise in a ____ state.

A

glycogen-depleted

68
Q

the liver can produce glucose from precursors released from active muscle: (2 precursors)

A
  1. lactic acid
  2. alanine
69
Q

Alanine is converted to glucose in the ____

supplies plasma glucose to ______

A
  1. converted to glucose in the liver
  2. Supplies plasma glucose to muscle
70
Q

**Alanine is an important source for gluconeogenesis in

A

long-term (hours) endurance exercise

up to 45% of liver glucose release is due to alanine

71
Q

Estimate ___% of total energy requirement for prolonged exercise is supplied by alanine-glucose cycle

72
Q

Maximal absolute rates of fat oxidation occur over a wide range of light to moderate exercise

**Fat max 55 to 72% VO2 max, corresponses to ___ HR Max

73
Q

**% of energy derived from fat decreases as exercise intensity __\_

Exercise Phys (6 decks)

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