Related Experiment Video
Updated: Oct 20, 2026

Evaluation of Respiratory Muscle Activation Using Respiratory Motor Control Assessment (RMCA) in Individuals with Chronic Spinal Cord Injury
Published on: July 19, 2013
Postinspiratory-ramp activity of diaphragm under inspiratory resistive load
1Istituto di Fisiologia Umana I, Università di Milano, Italy.
Abstract:
Inspiratory ramp activity, postramp activity (PRA) of diaphragm and respiratory flow were studied in anesthetized rabbits and conscious humans under inspiratory resistive load. Under load with chloralose-urethane anesthesia neural inspiration lasted 124 +/- 12 msec more than under control conditions and end of mechanical inspiration lagged behind that of neural inspiration by 114 +/- 4 msec. With pentobarbital-urethane anesthesia corresponding changes under load were 67 +/- 18 msec and 44 +/- 6 msec; after SO2 block of slowly adapting stretch receptors in bronchi corresponding changes under load were nil and 65 +/- 7 msec. In humans corresponding changes under load were about 192 and 127 msec. Both in rabbits and humans time course of PRA under load was essentially unchanged. Hence, under load a considerable part of PRA (or all of it under pentobarbital-urethane anesthesia without SO2 block) occurred during inspiration and that occurring during expiration was smaller than under control conditions. Consequently, under load braking of expiratory flow was smaller and peak expiratory flow occurred earlier than under control conditions.
Related Concept Videos
Mechanism of Breathing I: Inspiration
The respiratory system, an essential network for breathing, comprises the conducting and respiratory zones, each playing a crucial role in the overall process of respiration. Let us explore the detailed mechanism of inspiration, or inhalation, which is the first phase of the respiratory cycle.
Pathway of Air during Inspiration
During inspiration, air enters our body through the nose or mouth and moves through the conducting zone,...
Mechanism of Breathing II: Expiration
Expiration, or exhaling, is a complex physiological process that begins as the inspiratory muscles begin to relax. This relaxation triggers a series of events that epitomize the efficiency of the respiratory system.
Mechanism of Expiration:
Mechanism of Breathing III: The Accessory Muscles
The respiratory system is a complex network that relies on primary respiratory muscles like the diaphragm, but also involves accessory muscles to enhance lung expansion and airflow during both inhalation and exhalation.
Enhancing Inhalation with Accessory Muscles:
Accessory muscles such as the sternocleidomastoid, scalene, intercostal, and abdominal muscles are crucial when additional respiratory effort is required, such as during deep...
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:
Pulmonary Ventilation: Inhalation
Boyle's law becomes particularly pertinent when examining respiratory...
Pulmonary Cycle: Exhalation

