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EPHE 441 - Midterm (A) > Bioenergetics and energy metabolism > Flashcards

Bioenergetics and energy metabolism Flashcards

1
Q

Metabolism

A

Chemical Reactions, pathways that result in synthesis or breakdown of molecules

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2
Q

Bioenergetics

A

Metabolic processes involved in converting food sources into biologically usable energy.

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3
Q

EE rises by around what from rest to exercise

A

15-25 x

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4
Q

VO2

A

ability to deliver and use oxygen

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5
Q

Physiological factors influencing VO2

A
  1. Delivery of oxygen to working muscles: Cardiorespiratory system
  2. Utilization of oxygen by working muscles: Metabolic system (Aerobic)
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6
Q

Two types of factors that influence O2 consumption

A

Central and Peripheral

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7
Q

Central Factors

A

Cardiac output which is:
Heart Rate
Stroke Volume (Training improves this)

Cardiac output = Heart Rate x Stroke Volume

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8
Q

Peripheral Factors

A

Extraction by tissues (a-vO2)

Oxygen carrying storage capacity & ability for cells to take O2 
Training increases (3)
-Capillary density 
-Mitochondria number
-Hb, Mb
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9
Q

When exercising systemic changes happen because

A

Muscle demand increases force/speed of muscle contraction

  1. Rate of cross-bridge cycling
  2. Recruitment of motor units
  3. Recruitment of different fiber types
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10
Q

Increased in rate of energy system pathways are supported by: (3)

A
  1. Respiratory Changes: increase in ventilation
  2. Cardiovascular changes: increase in q (HR x SV)
    Vasodilation in working muscle
  3. Muscle Changes: increase Ca release/uptake by SR
    Increase myoglobin shuttling
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11
Q

Order of Energy Systems starting up

A

Creatine phosphate (alactic)
Lactic (glycolysis)
lastly aerobic

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12
Q

When our cells have a choice of the three energy systems for ATP synthesis what is our go to system? Why?

A

Go to system always aerobic

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13
Q

Anaerobic lactic system

A

Involves glycolysis only
Takes place in cytoplasm- close to contractile unit of muscle
Safety valve for the aerobic energy system for when O2 isnt available or ATP is being demanded at a greater rate than the aerobic system can supply itself

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14
Q

CP-ATP system (Anaerobic Alactic)

A

CP in cell is 4-6X greater than ATP
CP is a high energy phosphate reservoir (last 8-12 seconds in an untrained individual, highly trained 15)
Crucial during transition from low to high energy demand.

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15
Q

Process of CP system

A

CP-> C+Pi+ Energy (Creatine Kinase enzyme)

ADP + Pi + Energy -> ATP (ATPase enzyme)

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16
Q

What is the power and capacity of each system

A
  1. Alactic: Highest power, lowest capacity (run out of creatine phosphate) need to resynthesize or cannot use energy system again
  2. In the middle
  3. Aerobic: lowest power, highest capacity
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17
Q

Power

A

Rate at which an energy system can produce ATP

18
Q

Capacity

A

Total amount of ATP than an energy system can produce

19
Q

O2 Deficit

A

Difference between oxygen uptake in the first few minutes of exercise and an equal time period after steady state has been obtained.

20
Q

Factors contributing to excess post exercise oxygen consumption (6)

A
  1. Resynthesis of PC in muscle
  2. Lactate conversion to glucose
  3. Restoration of muscle and blood oxygen stores
  4. Elevated body temperature
  5. Post-exercise elevation of HR and Breathing
  6. Elevated Hormones
21
Q

How we get CrP stores back

A

ATP -> ADP + Pi + Energy
——–>
C + Pi + Energy –> CP

22
Q

Resynthesis of CP stores

A

15s - 68.7 %
60s - 81.0 %
180s - 92.0 %

For every second worked about 10-12 seconds of recovery is needed.

23
Q

Control Systems during exercise

A

Demands for energy vs Supply of Energy

24
Q

Energy Demand

A

How much energy is needed
What intensity is the muscle working
How long has the muscle been working at intensity (duration)

25
Q

Energy Supply

A

What fuels are available

Can metabolic process supply ATP at a high enough rate

26
Q

Short term high intensity =

A

Greater contribution of anaerobic energy systems

27
Q

Long term, low to moderate intensity

A

Majority ATP produced aerobically

28
Q

Energy Requirements at Rest

A 
Almost 100% of ATP produced by aerobic metabolism 
Blood lactate levels are low 
Resting O2 consumption 
0.25 L/min 
3.5 ml/kg/min
29
Q

Rest to Exercise Transitions

A

ATP production increases immediately
Oxygen uptake increases rapidly (Reaches steady state within 1-4 minutes)
Initial ATP production anaerobic
Oxygen deficit

30
Q

Steady State reached means

A

ATP requirement is met through aerobic ATP production.

31
Q

Trained subject have lower Oxygen Deficit why?

A

Better developed aerobic bioenergetic capacity
CVD and muscular adaptations
= Results in less production of lactate and H+

32
Q

Recovery from Exercise

A 
Oxygen uptake remains elevated above rest during recovery from exercise 
Oxygen debt (repayment for O2 deficit at onset of exercise) 
EPOC - terminology reflects only 20% elevated o2 consumption used to repay O2 deficit.
33
Q

Rapid portion of O2 debt

A
  1. Resynthesizes stored PC

2. Replenshes muscle and blood O2 stores

34
Q

Slow Portion of O2 debt

A
  1. Elevated heart rate and breathing= increases energy need
  2. Elevated body temperature= Increases in metabolic rate
  3. Elevated epinephrine and norepinephrine= Increase in metabolic rate
  4. Conversion of lactic acid to glucose (gluconeogenesis)
35
Q

Why EPOC greater following high intensity exercise

A
  1. Higher body temperature
  2. Greater depletion of PC (additional 02 required for resynthesis)
  3. Greater blood concentrations of lactic acid (additional o2 required for greater level of gluconeogenesis)
  4. Higher levels of blood epinephrine and norepinephrine.
36
Q

Removal of Lactic Acid following exercise

A

70% of lactic is oxidized by cells (Used as a substrate by heart and skeletal muscle)
20% converted to glucose
10% converted to amino acids

37
Q

Lactic Acid removed more rapidly from blood if

A

Light exercise performed during recovery.

Optimal intensity is 30-40% VO2 max.

38
Q

Metabolic Responses to Short Term High Intensity Exercise

A

First 1-5 Seconds of exercise: ATP produced via ATP-PC system
Intense exercise longer than 5s: Shift ATP production via glycolysis
Events lasting longer than 45 seconds: All three systems
60s: 70% anaerobic, 30% aerobic
120s: 50% anaerobic, 50% aerobic

39
Q

Metabolic responses to prolonged exercise (>10 minutes)

A

ATP production primarily aerobic
Steady state O2 uptake maintained during submax exercise
Hot Humid environment or High intensity: Upward drift in O2 uptake over time from increase in body temp and increases blood levels of epinephrine and norepinephirne.

40
Q

Lactate Threshold

A

Point at which blood lactic acid rises systematically during incremental exercise
Appears 50-60% VO2 max in untrained individuals
65-80% in trained subjects

Also called:
Anaerobic threshold
OBLA (When blood lactate levels reach 4 mmol/L)

41
Q

Reasons for Lactate Threshold (4)

A
  1. Low muscle oxygen (hypoxia)
  2. Accelerated glycolysis: -NADH produced faster than it is shuttled into mitochondria
    - Excess NADH in cytoplasm converts pyruvic acid to lactic acid.
  3. Recruitment of fast twitch muscle fibers: LDH isozyme in fast fibers promotes lactic acid formation
  4. Reduced rate of lactate removal from the blood: Liver removes lactate from blood.
42
Q

Practical Uses of Lactate Threshold

A

Prediction of Performance (Combined with exercise economy)

Planning training programs (marker of training intensity, choose a training HR based on LT)

EPHE 441 - Midterm (A) (6 decks)

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