Related Experiment Video
Updated: Aug 16, 2026

Evaluation of Respiratory System Mechanics in Mice using the Forced Oscillation Technique
Published on: May 15, 2013
The effect of lung reflexes on the pattern of breathing in cats
Abstract:
Tidal volume (VT), and inspiratory (tI) AND EXPIRATORY (TE) durations have been measured in anaesthetized cats on stimulation of alveolar type J (nociceptive) and lung irritant receptors by intravenous injections of phenyl diguanide and of histamine acid phosphate respectively. The reflexes were studied during eupnoea, hypercapnic and hypoxic hyperpnoea, during rebreathing from hyperventilation apnoea and at different body temperatures. In all conditions the drugs caused rapid shallow breathing with reduction in VT, tI and tE. The VT/tI relationship for injection of the drugs was different from that caused by hypercapnic stimulation of breathing, but the tI/tE relationship was proportionally similar for all conditions. Recording single unit activity from phrenic motor fibres showed that the lung reflexes had little action on the initial frequency of discharge of the fibres, but cut short the discharge earlier than for the controls. The results are interpreted in terms of the ways in which lung reflexes can modify the pattern of breathing.
More Related Videos
Related Concept Videos
Respiratory Volumes and Capacities I
Assessment of Ventilation II: Respiratory Depth and Rhythm
Respiratory depth measures the volume of air inhaled or exhaled during a breath. It can vary from shallow to deep and typically remains consistent when a person is at rest or asleep. Occasionally, individuals will automatically inhale deeply, known as sighing, which inflates the lungs with more air than normal breathing.
To assess respiratory depth, observe the degree of chest excursion or movement:
Alterations in Respiration II
In Biot's breathing, the respiratory rate and depth are irregular, alternating between periods of deep gasping and apnea. Common causes include...
Factors Affecting Pulmonary Ventilation
Alveolar Surface Tension
The alveolar fluid lines the luminal surface of the alveoli and exerts a force called surface tension. This force is caused by the polar water molecules in the liquid being more strongly attracted to each...
Other Factors Affecting Respiration Centers
However, the ability to hold one's breath voluntarily is not limitless. When the CO2 concentration in the blood reaches a critical level,...
Physical Assessment of the Respiratory Tract II: Inspection
Chest Configuration
The chest configuration can...

