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Abdominal muscle length during respiratory defensive reflexes
E van Lunteren1, J S Arnold, M A Haxhiu
1Department of Medicine (Pulmonary Division), Case Western Reserve University, Cleveland, Ohio.
Respiration Physiology
|November 1, 1991
Summary
Defensive reflexes like coughing and sneezing significantly increase the speed, but not the extent, of transversus abdominis muscle shortening. This expiratory muscle plays an active role in these vital respiratory actions.
Area of Science:
- Physiology
- Respiratory Mechanics
- Muscle Physiology
Background:
- The transversus abdominis is a key expiratory muscle involved in breathing and forceful expiratory events.
- Understanding its mechanical behavior during defensive reflexes is crucial for respiratory physiology.
Purpose of the Study:
- To investigate the mechanical properties of the transversus abdominis muscle during defensive reflexes (coughing and sneezing).
- To compare muscle length changes and shortening velocity during these reflexes versus normal breathing.
Main Methods:
- Utilized sonomicrometry to measure transversus abdominis muscle length changes in anesthetized dogs.
- Recorded muscle activity during spontaneous breathing, coughing, and sneezing.
Main Results:
- Transversus abdominis muscle shortened rapidly during the expiratory phase of coughs and sneezes.
- Muscle shortening extent was similar during coughing but doubled during sneezing compared to breathing.
- Peak shortening velocity was significantly higher during coughing (5-fold) and sneezing (10-fold) than during breathing.
Conclusions:
- Defensive reflexes elicit greater increases in the velocity than the extent of transversus abdominis muscle shortening.
- The transversus abdominis muscle actively contributes to respiratory function during defensive reflexes.
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