SCT III - Muscle Energetics Flashcards
What are the types of muscle?
Speed of Contraction
- Fast
- Slow
Source of Energy
- Oxidative
- Glycolytic
Could be:
1. Fast oxidative
2. Fast glycolytic
3. Slow oxidative
4. Slow glycolytic
What is the classification of slow oxidative skeletal muscles (red)?
Myosin Isoenzyme: Slow
SR Calcium Pumping Capacity: Moderate
Diameter: Moderate
Oxidative capacity: High
Glycolytic capacity: Moderate
Mechanical response: Slow
Basically myosin isoenzyme ^^^
What is the classification of fast glycolytic skeletal muscle (white)?
Myosin Isoenzyme: Fast
SR calcium pumping capacity: High
Diameter: Large
Oxidative capacity: Low
Glycolytic capacity: High
Mechanical response: Fast
What is the classification of fast oxidative skeletal muscle (red)?
Myosin isoenzyme: Fast
SR calcium pumping capacity: High
Diameter: Small
Oxidative capacity: VERY high
Glycolytic capacity: High
Mechanical response: fast
What gives muscle fibers their red color?
Excess of mitochondria
How does the fast oxidative muscle fiber have high oxidative and high glycolytic activity?
High oxidative activity requires metabolites from glycolysis, therefore, it needs to do glycolysis thoroughly before running intense oxidative processes
What is the function of creatine phosphate?
To keep ATP sources constant by:
Creatine-phosphate → Creatine
ADP → ATP via the process
Is glycolysis an aerobic or anaerobic process?
Anaerobic
How is the limit of glycolysis mediated in the body?
Body reaches “anaerobe threshold” where it cannot take anymore lactic acid, and switches to aerobic respiration
What is the optimum load of muscle performance?
1/3 of the maximum force
How long does the creatine phosphate last for during intense exercise?
8-10 seconds
What happens at increased O2 consmption?
Respiratory rate (RR) ↑
Tidal volume (TV) ↑
Maximum stroke volume (SV) ↑
O2 alveolar diffusion ↑
Maximum AV O2 difference ↑
What is the local response to the muscles during physical exercise?
VASODILATION
- Due to sympathetic cholinergic activity
- Due to increased metabolites
- To bring the muscle more blood (nutrients)
What are the changes in systemic circulation that take place during physical exercise?
Heart rate (HR) ↑
Cardiac Output (CO) ↑
Stroke Volume (SV) ↑
Flow of pulmonary circulation ↑
Peripheral resistance (TPR) ↓ - Due to Vasodilation
Redistribution of the circulating blood volume
Summary of circulatory response by the brain to exercise (drawing)
Why does the skin blood flow decrease, then increase?
Decreases due to vasoconstriction for blood redistribution
Increases later due to vasodilation for heat loss (body gets hot during exercise)
How do you calculate the minute volume?
MV = Tidal Volume (TV) x Respiratory Rate (RR)
What happens to the minute volume and the heart rate during increasing exercise intensity?
Exercise Intensity ↑
Minute Volume ↑
Heart Rate ↑
What happens to stroke volume during exercise?
Initially, SV spikes higher than HR. However, later on, SV plateaus due to the heart compensating:
Filling time ↓
VR ↓
SV ↓ (Frank starling)
What are all the cardiovascular parameter changes that occur during exericse?
MAP ↑ (↑↑↑CO & TPR ↓ - CO dominant)
SP ↑ (Proportional to SV ↑)
EDV ↑ (Resp. pump - VR ↑)
DP ↓ (Proportional to TPR ↓)
ESV ↓ (SNS +ve Intropic)
What is reactive hyperemia and when does it take place?
temporary increase in blood flow (vasodilation) to an area following a period of reduced or obstructed blood supply.
This happens due to muscle pump (compression of vessels during muscle flexion)
How is heat regulated during exercise?
- Sweating
- Vasodilation of the skin vessels, bringing blood closer to surface
How is ventilation impacted during exercise?
Exercise ↑
Ventilation ↑
What is endurance?
Is the maximal oxygen uptake (liter per minute)
How is performance and time correlated?
What is oxygen debt?
Extra oxygen required after exercise to restore the body to its resting state:
- Replenishing O2 stores (myoglobin)
- Replenishing creatine-phosphate pool
- Eliminating lactic acid
What happens to heartrate during oxygen debt?
HR increases during oxygen debt
HR decreases during repayment of debt
