5.4 Acute responses of the respiratory and muscular system Flashcards
(17 cards)
What is respiratory rate / respiratory frequency and how does it change during exercise?
Respiratory rate is the number of breaths taken per minute. It increases from 12 at rest to 35-50 during maximal exercise.
What is tidal volume and how does it change during exercise?
tidal volume is the amount of air breathed in or out per breath. it increases from 0.5L at rest to 3-5 L at maximal workloads.
What is ventilation and how is it calculated
Ventilation is the amount of air breathed in or out per minute. It is calculated as:
Ventilation = Respiratory rate × Tidal volume
How does ventilation change from rest to maximal exercise?
Ventilation increases from ~5–6 L/min at rest to beyond 130–180 L/min during maximal exercise (higher for males due to larger lung volume).
What causes the initial increase in ventilation at the start of exericse?
Neural signals from the brain and muscles trigger the respiratory control centres.
What causes the further increase in ventilation as exercise continues?
Increased carbon dioxide and hydrogen ions in the blood stimulate chemoreceptors, which increase breathing rate and depth.
what is pulmonary diffusion
the gas exchange between alveoli and capillaries- oxygen in, carbon dioxide out
How does pulmonary diffusion change during exercise.
Oxygen diffusion capacity increases up to 3× its resting level (from ~21 mL/min), improving O₂ uptake and CO₂ removal.
Respiratory acute responses
- respiratory frequency
- tidal volume
- ventilation
- oxygen uptake
- maximum O2 uptake
What happens to motor unit and muscle fibre recruitment during exercise?
More motor units and muscle fibres are recruited to meet increased force demands.
what is the arteriovenous oxygen difference and how does it change during exercise?
it increases as working muscles extract more oxygen from the blood- up to 75% of available oxygen.
Why does muscle temperature increase during exercise
because it increases blood flow and ATP production generate heat, raising muscle temperature.
what happens to muscle enzyme activity during exercise?
It increases to help resynthesise ATP more rapidly via all three energy systems.
What role do enzymes like ATP synthase play in exercise?
They help convert ADP + Pi into ATP, providing energy for muscle contraction.
how does oxygen use in muscles change during exercise?
Muscles extract and use more oxygen to meet energy demands
What are the key muscle substrates that decrease during exercise?
ATP, creatine phosphate, glycogen, and triglycerides all decrease due to use for energy.
How does muscle blood flow change during exercise?
Increases from 15-20% of cardiac output at rest to 80-90% during exercise.
