RESUMEN
Frequency and impulse responses were determined for isolated guinea pig outer hair cells by electrically stimulating the cells between two wire electrodes with white noise. Cells were attached to the bottom of a small culture dish at one end while the other end was freely moving. Results have the character of a damped second-order system, with a cut-off frequency of approximately 7 kHz. Correspondingly, impulse responses show a single narrow peak roughly 50 microseconds wide and have the shape of the impulse response for a critically damped harmonic oscillator.
Asunto(s)
Movimiento Celular/fisiología , Células Ciliadas Auditivas Externas/citología , Estimulación Acústica , Animales , Separación Celular , Cóclea/citología , Cóclea/fisiología , Estimulación Eléctrica , Cobayas , Células Ciliadas Auditivas Externas/fisiología , Concentración OsmolarRESUMEN
Whether the occlusion between hypopharynx and esophagus is established by anatomical relations and tissue elasticity or by a functional resting tone of the muscle fibers is not quite clear. This study describes simultaneous electromyography (EMG) and electromanometry in the pharyngoesophageal segment to solve this problem and investigate the complex mechanism of deglutition. To register the EMG from the hypopharyngeal constrictor muscle and the upper esophageal sphincter (UES), two copper wire electrode pairs with hooked bare ends were used. These electrodes were introduced into the muscles through a rigid esophagoscope. It is demonstrated that at rest muscle activity is present in the UES. This activity disappears during the relaxation period. Simultaneous manometry and EMG is a valuable supplement to diagnostic procedures in dysphagia patients.