Ventilatory Muscle Activity in Intact Preparations of Aeshnid Dragonfly Larvae

1972 ◽  
Vol 56 (2) ◽  
pp. 527-536
Author(s):  
R. S. PICKARD ◽  
P. J. MILL
Keyword(s):  
Muscle Activity ◽  
Mechanical Effect ◽  
Critical Position ◽  
Normal Ventilation

1. The expiratory role of the segmental, respiratory dorso-ventral muscles, and the inspiratory role of the subintestinal muscle, have been confirmed using intact preparations of aeshnid dragonfly larvae. 2. The strain developed by individual respiratory dorso-ventral muscles has been measured. 3. The respiratory dorso-ventral muscles all cease firing simultaneously, about 100 msec before the sterna are fully raised, and do not have any mechanical effect on the sterna after this time. It is suggested that the delay is caused either because the role of these muscles is to lift the sterna past some critical position, and/or because of the inertia of the expiratory current. 4. Periodically the sterna are raised and then lowered slowly in a series of steps, each pause in the lowering coinciding with activity in the respiratory dorso-ventral muscles. This form of ventilation is compared with others previously described. 5. In normal ventilation, and in other types of ventilation, activity in the respiratory dorso-ventral muscles shows a pronounced tendency to begin in the most posterior segments and to continue for longer periods in those segments. 6. Some aspects of the central neural connexions involved in normal ventilation are discussed.

Role of Muscle Activity in Nerve-Muscle Interaction in vitro

Nature ◽  
1974 ◽  
Vol 248 (5443) ◽  
pp. 70-71 ◽  
Author(s):  
J. H. STEINBACH
Keyword(s):  
Muscle Activity ◽  
Nerve Muscle

Kinematic and Electromyographic Analysis of the functional role of the body axis during Terrestrial and Aquatic Locomotion in the Salamander Ambystoma Tigrinum

1992 ◽  
Vol 162 (1) ◽  
pp. 107-130 ◽  
Author(s):  
LARRY M. FROLICH ◽  
ANDREW A. BIEWENER
Keyword(s):  
Muscle Activity ◽  
Functional Role ◽  
The Body ◽  
Ambystoma Tigrinum ◽  
Terrestrial Locomotion ◽  
Aquatic Locomotion ◽  
Wave Patterns ◽  
Axial Morphology ◽  
Electromyographic Analysis

Aquatic neotenic and terrestrial metamorphosed salamanders {Ambystoma tigrinum) were videotaped simultaneously with electromyographic (EMG) recording from five epaxial myotomes along the animal's trunk during swimming in a flow tank and trotting on a treadmill to investigate axial function during aquatic and terrestrial locomotion. Neotenic and metamorphosed individuals swim using very similar axial wave patterns, despite significant differences in axial morphology. During swimming, both forms exhibit traveling waves of axial flexion and muscle activity, with an increasing EMG-mechanical delay as these waves travel down the trunk. In contrast to swimming, during trotting metamorphosed individuals exhibit a standing wave of axial flexion produced by synchronous activation of ipsilateral epaxial myotomes along the trunk. Thus, metamorphosed individuals employ two distinct axial motor programs -- one used during swimming and one used during trotting. The transition from a traveling axial wave during swimming to a standing axial wave during trotting in A. tigrinum may be an appropriate analogy for similar transitions in axial locomotor function during theoriginal evolution of terrestriality in early tetrapods.

Mechanics of the fast-start: muscle function and the role of intramuscular pressure in the escape behavior of amia calva and polypterus palmas

1998 ◽  
Vol 201 (22) ◽  
pp. 3041-3055 ◽  
Author(s):  
MW Westneat ◽  
ME Hale ◽  
MJ Mchenry ◽  
JH Long
Keyword(s):  
Muscle Activity ◽  
Escape Response ◽  
Muscle Force ◽  
Escape Behavior ◽  
Pressure Change ◽  
The Body ◽  
Intramuscular Pressure ◽  
Fast Start ◽  
Amia Calva

The fast-start escape response is a rapid, powerful body motion used to generate high accelerations of the body in virtually all fishes. Although the neurobiology and behavior of the fast-start are often studied, the patterns of muscle activity and muscle force production during escape are less well understood. We studied the fast-starts of two basal actinopterygian fishes (Amia calva and Polypterus palmas) to investigate the functional morphology of the fast-start and the role of intramuscular pressure (IMP) in escape behavior. Our goals were to determine whether IMP increases during fast starts, to look for associations between muscle activity and elevated IMP, and to determine the functional role of IMP in the mechanics of the escape response. We simultaneously recorded the kinematics, muscle activity patterns and IMP of four A. calva and three P. palmas during the escape response. Both species generated high IMPs of up to 90 kPa (nearly 1 atmosphere) above ambient during the fast-start. The two species showed similar pressure magnitudes but had significantly different motor patterns and escape performance. Stage 1 of the fast-start was generated by simultaneous contraction of locomotor muscle on both sides of the body, although electromyogram amplitudes on the contralateral (convex) side of the fish were significantly lower than on the ipsilateral (concave) side. Simultaneous recordings of IMP, escape motion and muscle activity suggest that pressure change is caused by the contraction and radial swelling of cone-shaped myomeres. We develop a model of IMP production that incorporates myomere geometry, the concept of constant-volume muscular hydrostats, the relationship between fiber angle and muscle force, and the forces that muscle fibers produce. The timing profile of pressure change, behavior and muscle action indicates that elevated muscle pressure is a mechanism of stiffening the body and functions in force transmission during the escape response.

Effects of postural changes and vestibular lesions on diaphragm and rectus abdominis activity in awake cats

2001 ◽  
Vol 91 (1) ◽  
pp. 137-144 ◽  
Author(s):  
L. A. Cotter ◽  
H. E. Arendt ◽  
J. G. Jasko ◽  
C. Sprando ◽  
S. P. Cass ◽  
...  
Keyword(s):  
Vestibular System ◽  
Muscle Activity ◽  
Abdominal Muscle ◽  
Rectus Abdominis ◽  
Abdominal Muscles ◽  
Body Rotation ◽  
Postural Changes ◽  
Before And After ◽  
Awake Cats

Changes in posture can affect the resting length of the diaphragm, requiring alterations in the activity of both the abdominal muscles and the diaphragm to maintain stable ventilation. To determine the role of the vestibular system in regulating respiratory muscle discharges during postural changes, spontaneous diaphragm and rectus abdominis activity and modulation of the firing of these muscles during nose-up and ear-down tilt were compared before and after removal of labyrinthine inputs in awake cats. In vestibular-intact animals, nose-up and ear-down tilts from the prone position altered rectus abdominis firing, whereas the effects of body rotation on diaphragm activity were not statistically significant. After peripheral vestibular lesions, spontaneous diaphragm and rectus abdominis discharges increased significantly (by ∼170%), and augmentation of rectus abdominis activity during nose-up body rotation was diminished. However, spontaneous muscle activity and responses to tilt began to recover after a few days after the lesions, presumably because of plasticity in the central vestibular system. These data suggest that the vestibular system provides tonic inhibitory influences on rectus abdominis and the diaphragm and in addition contributes to eliciting increases in abdominal muscle activity during some changes in body orientation.

Relation Between Activities of the Cortex and Vibrissae Muscles During High-Voltage Rhythmic Spike Discharges in Rats

2005 ◽  
Vol 93 (5) ◽  
pp. 2435-2448 ◽  
Author(s):  
Fu-Zen Shaw ◽  
Yi-Fang Liao
Keyword(s):  
High Voltage ◽  
Muscle Activity ◽  
Oscillation Frequency ◽  
Muscular Activity ◽  
Simultaneous Recording ◽  
Absence Seizure ◽  
Mu Rhythm ◽  
Oscillation Frequencies ◽  
Peripheral Sensory

Paroxysmal 5- to 12-Hz high-voltage rhythmic spike (HVRS) activities, which are accompanied by whisker twitching (WT), are found in Long Evans rats, but the function of these HVRS activities is still debated. In four major functional hypotheses of HVRS discharges, i.e., alpha tremor, attention/mu rhythm, idling/mu rhythm, and absence seizure, the first two hypotheses emphasize WT behavior in HVRS bouts. Whisker movement is primarily determined by activation of intrinsic and extrinsic muscles. To clarify the role of WT in HVRS activities, simultaneous recording of the activities from the cortex and intrinsic/extrinsic and neck muscles were performed. Most HVRS bouts (68.8%) revealed no time-locked WT behavior in a 2-h recording session. In addition, WT primarily arose from active protraction due to activation of intrinsic muscles followed by passive retraction. A small portion of WT resulted from activation of both vibrissae muscles with dynamic frequency-dependent phase shifts. Onset of the rhythmic vibrissae EMG significantly lagged behind HVRS onset, and the mean duration of vibrissae muscle activity was one-third to a one-half of a HVRS bout. Moreover, a greater number of HVRS bouts were associated with a longer HVRS duration and higher oscillation frequency. Oscillation frequencies of HVRS activities without WT behavior were significantly lower than those with WT. Under peripheral sensory/motor blockade by xylocaine injection, oscillation frequencies of HVRS bouts significantly decreased, but no remarkable changes in the number or duration of HVRS bouts were observed. Compared with vibrissa muscle activity during WT and exploratory whisking, the duration of muscular activity in each cycle was apparently longer during whisking bouts. Based on these results, overemphasis of the role of WT on HVRS activities might not be appropriate. Instead, HVRS discharges may be associated with absence seizure or idling state. In addition, peripheral inputs, including WT, may elevate the oscillation frequency of HVRS bouts. Moreover, different muscular controls may exist between WT and whisking.

Tour guides and the transnational promotion of human rights: Agency, structure and norm translators in responsible travel

2020 ◽  
Vol 20 (3) ◽  
pp. 314-335
Author(s):  
Jonathan Liljeblad
Keyword(s):  
Human Rights ◽  
Theoretical Concept ◽  
Case Study Approach ◽  
Critical Position ◽  
Tour Guide ◽  
Study Approach ◽  
Tour Guides ◽  
Tourism Studies

Within tourism studies, the movement for ‘responsible tourism’ seeks to direct tourism in support of ideals such as sustainability and human rights. Central to the promotion of such ideals, however, is the tour guide who holds a critical position influencing the orientation of a tourism encounter. This article explores the capacities of tour guides to direct tourism encounters in support of human rights. The analysis draws upon tourism and human rights literature to frame tour guides within the theoretical concept of norm translators. The analysis applies a case study approach to a case of an individual tour guide leading a Vietnam tour package under the employ of a responsible travel company supportive of human rights, with the purpose of clarifying the role of tour guides in promoting human rights and elaborating the theory of norm translators.

Decompression to altitude: assumptions, experimental evidence, and future directions

2009 ◽  
Vol 106 (2) ◽  
pp. 678-690 ◽  
Author(s):  
Philip P. Foster ◽  
Bruce D. Butler
Keyword(s):  
Skeletal Muscle ◽  
Experimental Evidence ◽  
Muscle Activity ◽  
Weight Bearing ◽  
Bubble Formation ◽  
Microgravity Environment ◽  
Physiological Variables ◽  
Orbital Space ◽  
Human Exploration

Although differences exist, hypobaric and hyperbaric exposures share common physiological, biochemical, and clinical features, and their comparison may provide further insight into the mechanisms of decompression stress. Although altitude decompression illness (DCI) has been experienced by high-altitude Air Force pilots and is common in ground-based experiments simulating decompression profiles of extravehicular activities (EVAs) or astronauts' space walks, no case has been reported during actual EVAs in the non-weight-bearing microgravity environment of orbital space missions. We are uncertain whether gravity influences decompression outcomes via nitrogen tissue washout or via alterations related to skeletal muscle activity. However, robust experimental evidence demonstrated the role of skeletal muscle exercise, activities, and/or movement in bubble formation and DCI occurrence. Dualism of effects of exercise, positive or negative, on bubble formation and DCI is a striking feature in hypobaric exposure. Therefore, the discussion and the structure of this review are centered on those highlighted unresolved topics about the relationship between muscle activity, decompression, and microgravity. This article also provides, in the context of altitude decompression, an overview of the role of denitrogenation, metabolic gases, gas micronuclei, stabilization of bubbles, biochemical pathways activated by bubbles, nitric oxide, oxygen, anthropometric or physiological variables, Doppler-detectable bubbles, and potential arterialization of bubbles. These findings and uncertainties will produce further physiological challenges to solve in order to line up for the programmed human return to the Moon, the preparation for human exploration of Mars, and the EVAs implementation in a non-zero gravity environment.

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