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Lung growth & aging
Summary
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Spirometry
Lung growth & aging
Bronchial hyperresponsiveness
Global Lung Function Initiative
GOLD controversy
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Contours of Breathing
Summary
Body height can be used to empirically
scale lung volumes
and
ventilatory flows
. However, this does not contribute to a fundamental
understanding
of the laws that govern a successful growth pattern as it does not take into account
changing body dimensions
during growth.
Throughout the process of lung growth the normal functioning of the organism as a whole must be warranted. In the first years there is growth of the number of alveoli and bronchi, and subsequently they simply
grow larger
.
As from age 6 year lungs and airways appear to grow proportionally:
isometric growth
.
The lung growth pattern in patients with asthma is similarly
isometric
.
Asthma patients, as well as individuals who experienced recurrent respiratory symptoms during infancy, exhibit a normal isometric growth pattern and yet appear to have
narrower airways
.
Due to the
elastic properties of lungs and chest
, the changes that occur with
growth and aging
, and the changes that occur in the
shape and properties of the thorax
, neonates and elderly subjects have dependent lung areas that are
poorly
or nonventilated (
airway closure
) during normal tidal breathing. On account of the shape of the oxyhemoglobin dissociation curve the poorer oxygenation of capillary blood in such lung compartments cannot be compensated by increased ventilation elsewhere. This may explain the lower
arterial oxygen pressures
observed in these subjects. Neonates, infants, toddlers and elderly subjects are therefore at greater risk of more extensive airway closure in the case of
e.g
. viral infections, and thus to a
compromised oxygen supply
, particularly when supine.
Soon after birth the
arterial carbon dioxide
tension attains adults values, which are maintained to a very high age. This indicates that the lung is up to its task of exchanging gas across the alveolar-capillary membrane.
Last modified on 11.07.2017 13:26
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Spirometry
Lung growth & aging
Bronchial hyperresponsiveness
Global Lung Function Initiative
GOLD controversy
Download
Contours of Breathing