Читать книгу Manual of Equine Anesthesia and Analgesia - Группа авторов - Страница 197

 Elastic resistance is a result of surface tension forces at the alveolar air‐liquid interface in addition to the elastic properties of the lung tissue matrix.

 Frictional resistance is primarily influenced by airway radius and length.The upper airways (nasal cavity, pharynx, and larynx) provide approximately 60% of the total resistance to breathing.The lower airway resistance primarily resides in the trachea and bronchi.The bronchioles provide only a small fraction of the total resistance due, in large part, to the low airflow in a high cross‐sectional area.

 Airway radius or diameter can be altered due to changes in the smooth muscle tone within the walls of airways.In the horse, smooth muscle extends from the trachea to the alveolar ducts.In general, parasympathetic mediated smooth muscle contraction results in airway narrowing and an increase in airway resistance.β‐adrenergic and nonadrenergic noncholinergic activation results in bronchodilation and a decrease in airway resistance.