Published On: Mon, Oct 1st, 2012

Regulation of Respiration, Musculature, Blood Vessels and Glands of Airways

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Regulation of Respiration

Respiration is regulated by the rhythmic discharges from the respiratory centre in the medulla. The discharges are modulated by input from pontine and higher (CNS) centers and vagal afferents from the lungs.

Various chemical factors affect the respiratory centre, including the partial pressure of carbon dioxide in the arterial blood by an action on medullary chemo receptors, and of oxygen by an action on the chemo receptors in the carotid bodies.

Some voluntary control can be superimposed on the autonomic regulation of breathing, by implying connections between the cortex and the motor neurons, innervating the muscles of respiration.
Bulbar poliomyelitis and lesions in the brain result in loss of the autonomic regulation of respiration without loss of voluntary regulation.

Regulation of Musculature, Blood Vessels and Glands of the Airways

Efferent pathways that control the airways consist of cholinergic parasympathetic nerves and non-noradrenergic non-cholinergic (NANC) inhibitory nerves. Inflammatory mediators and NANC bronchoconstrictor mediators play a role in the diseased airways. The afferent pathways include three different types of sensory receptors.

The airway resistance is influenced by the tone of the bronchial muscle, state of the mucosa and the activity of the glands in the with and bronchitis.

Airway resistance can be measured indirectly by the instruments that record the volume or flow of the forced expiration. FEV1 is the forced expiratory volume in 1 second. The peak expiratory flow rate (PEFR) is the maximal flow after a full inhalation. It is expressed as l/min. This is the simpler method than FEV1 as it can be measured at the bedside.

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