Obesity produces
decreased tidal volume and functional residual capacity,
both of which reduce the tidal stretch of smooth muscle thus,
the ability to respond to natural stress such as exercise is hampered
by small tidal volumes [45]. Also, Obesity increased
gastro-esophageal reflux due to accompanied esophageal
sphincter relaxation, resulting in esophageal acid reflux passing
into the trachea and airways. The direct contact of gastric acid
with the airways causes bronchoconstriction owing to the
resulting micro-aspiration or to the vagal reflex [46]. Leptin
plasma levels have been positively correlated with body fat,
stimulating the release of tumor necrosis factor (TNF-a) by
adipocytes and act on the sympathetic nervous system which
is crucial in controlling airway tone and diameter; important
factors in asthma [47]. TNF-a is elevated in asthma and is
related to the production of T helper-2 cytokines as IL-4
[48]. There are common genes, playing a role in both asthma
and obesity as chromosomes 5q, 6, 11q13, and 12q [45].
Adipose tissue contains the enzyme aromatase, which is
responsible for converting androgens into estrogens causing
airway hyper-reactivity and greater severity of irreversible airflow
obstruction [49].
Obesity producesdecreased tidal volume and functional residual capacity,both of which reduce the tidal stretch of smooth muscle thus,the ability to respond to natural stress such as exercise is hamperedby small tidal volumes [45]. Also, Obesity increasedgastro-esophageal reflux due to accompanied esophagealsphincter relaxation, resulting in esophageal acid reflux passinginto the trachea and airways. The direct contact of gastric acidwith the airways causes bronchoconstriction owing to theresulting micro-aspiration or to the vagal reflex [46]. Leptinplasma levels have been positively correlated with body fat,stimulating the release of tumor necrosis factor (TNF-a) byadipocytes and act on the sympathetic nervous system whichis crucial in controlling airway tone and diameter; importantfactors in asthma [47]. TNF-a is elevated in asthma and isrelated to the production of T helper-2 cytokines as IL-4[48]. There are common genes, playing a role in both asthmaand obesity as chromosomes 5q, 6, 11q13, and 12q [45].Adipose tissue contains the enzyme aromatase, which isresponsible for converting androgens into estrogens causingairway hyper-reactivity and greater severity of irreversible airflowobstruction [49].
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