Week 11 Flashcards
Minute ventilation is…
volume of air inspired/expired in 1 minute (in L/min)
Minute ventilation can increase by increasing ____ or ____
tidal volume or breathing frequency
Minute ventilation at rest is about ___L/min
8-10
Maximal rates of ventilation can exceed ___L/min in large endurance athletes
200
Ventilation increases in proportion to ___ uptake at lower intensities and disproportionately more as maximum VO2 is approached
O2
Circulatory & ventilatory responses to progressive exercise both involve:
a) A volume that is related to body mass (stroke volume, tidal volume)
b) A size-independent time-defined factor (HR, breathing frequency)
SV +/or heart rate —>
CO
Tidal volume +/or breathing frequency —>
Minute ventilation
Maximal minute ventilation is not an expression of the limits of ventilatory capacity. It also reflects the influences of excessive CO2 produced by the buffering of lactate and the need to reduce ____ _____.
metabolic acidosis
Vital capacity is the…
maximum amount of air that can be expelled from lungs during maximal inhalation
Vital capacity increases with age in direct/indirect proportion to body size
direct
Both absolute and relative (adjusted for body size) forced vital capacity is greater in ____ than _____ at ALL ages.
males, females
At rest, absolute tidal volume _____ with lung growth. However, the proportion of vital capacity used for ___ ____ declines as children age
increases, tidal volume
As children age, what three processes decline?
- Resting breathing frequency
- tidal volume as a % of vital capacity
- relative minute ventilation
Absolute minute ventilation _____ with age.
increases
At rest: Absolute increases in minute ventilation are driven by absolute increases in tidal volume whilst _____ _____ declines during childhood. However, when expressed relative to body size, resting ____ ____ decreases during childhood
breathing frequency, tidal volume
Absolute maximal minute ventilation increases as lung volume increases, but it can also be influenced by maturational changes in _____ ______ and factors governing cellular acidosis.
lactate production
A study found that maximal minute ventilation was relatively stable in ___ but declined in ___
boys, girls
A study found a fairly stable relative maximal minute ventilation in boys. Decline after ..?
Teenage years
Breathing frequency at maximal exercise slowly _____ with age during childhood, and values are independent of body size (no difference found in M vs F)
declines
Absolute values of tidal volume at maximal exercise _____ with growth in accord with greater lung dimensions—> The breathing frequency (fR) to tidal volume (VT) ratio therefore falls as a child grows–>Studies unsure whether greater ratio in boys or girls
increase
Maximal exercise: as children grow, maximal ______ _____ slows, and absolute maximal minute ventilation and absolute maximal tidal volume increase
breathing frequency
The energy expenditure of the breathing muscles to achieve minute ventilation is influenced by both …?
- the compliance of the lungs and chest wall
- resistance to airflow within the airways
The compliance of the lungs ______ during childhood, particularly in the early years, at the same time airway resistance ____
improves, diminishes
Suggests, energy demands of ventilation during exercise may be greater in _________, although evidence is lacking for high intensities
small children
Greater reliance on breathing frequency (as opposed to tidal volume) increases the ventilatory work needed to overcome ____ _____ (in children)
airway resistance
Adults: tidal volume increases to 60% vital capacity, and at higher intensities increases are provided by increased ???????
breathing frequency
Children: some evidence indicates a linear increase in tidal volume and plateau in breathing frequency at 67% peak exercise
However, other evidence suggests similar patterns to adults. i.e. increase reliance on _____ -_____ at higher intensities
breathing frequency
Does dead-space change with age?
A study found no age-related differences in dead space for a given tidal volume in boys aged 9-15, cycling at same workload
End tidal CO2 during exercise is ______ in children than in adults
lower
Lactate production is ___ in children compared with adults
lower
There is ____ metabolic acidosis (i.e. higher pH) in children than adults
less
Children ventilate ___ than adults during first rest intervals to exhale a given amount of CO2, allowing them to regulate their PaCO2 to a lower level.
more
Do adults or children ventilate (breathe) more?
Children (declines with age)
During exercise the transit time for O2 to move from the alveoli into the pulmonary capillaries is ___
reduced (can lead to arterial hypoxaemia)
Ventilatory drift:
increases in breathing frequency and minute ventilation, but decline in tidal volume
Ventilatory drift is generally linked to increase in…
metabolic heat production and core temperature
Lung compliance is ___ and airway resistance is ___ in children, but these approach adult values in the later years
less, greater
Normal arterial oxygenation is maintained in ____ at maximal exercise, but data in child athletes is lacking
children
Children demonstrate characteristics of ventilatory drift during sustained steady-state exercise similar/different to adults
similar
During childhood, increases in absolute minute ventilation at rest are driven by..?
Increases in absolute tidal volume
When considering maximal exercise, what happens to the breathing frequency to tidal volume ratio as children grow?
It falls, i.e. greater dependence on increases in tidal volume during exercise
Why might the energy demands of ventilation during exercise be greater in small children compared with older children or young adults?
Greater airway resistance
