Spirometry And Gas Transport Flashcards
How do you work out minute volume?
Minute volume = tidal volume x respiratory rate
What is alveolar ventilation?
Amount of air reaching the alveoli per minute
What is the difference between shallow and deep breathing?
Shallow - (150-150) x 40 = 0
Deep - (1000-150) x 6 = 5100
What does the respiratory exercise centre in the medulla do?
Innervates neural and humoral factors to produce a ventilatory pattern entirely appropriate to the metabolic demands of that particular time
What happens to ventilation at the onset of exercise?
Phase l
- neurogenic, from both cortex and periphery
Phase ll
- exponential increases, some chemoreceptor phasic input
Phase lll
- fine tuning, steady state, chemoreceptor drive
Describe the carriage of O2
67x carriage by plasma alone
Plateau of reserve
Releases to tissue made easy
Bohr effect
Temp effect
Describe the carriage of CO2
7% dissolved in plasma
23% as carb amino compounds (Hb)
Most important in bicarbonate
CO2 + H2O <> H2CO3 <> H+ + HCO3-
What happens to blood gases during exercise?
Increasing exercise increases ventilation linearly with VO2 until a certain point
- ventilators threshold
At this point it breaks linearity due to lactic acid stimulating chemoreceptors
Blood gases then fall for CO2 and rise for O2
What is the anaerobic threshold?
Below it the muscles demands O2 are met by aerobic respiration
Above it the muscles respire anaerobically and produce lactate
What happens above the anaerobic threshold?
Hyperventilation and change in respiration exchange ratio
Acidosis
Unmaintainable exercise level
Is it ventilation that limits athletic performance?
Not usually
Cardiovascular system normally limits performance
What is the Bohr effect?
Haemoglobin has a lower affinity to O2 secondary to increases in partial pressure of CO2 in the tissues
This allows a preference for unloading O2 and removing CO2
