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Frequency intervals
| Interval | Frequency (Hz) | Physiological origin |
|---|---|---|
| I | 0.6–2.0 | heartbeat |
| II | 0.145–0.6 | respiratory activity |
| III | 0.052–0.145 | intrinsic myogenic activity |
| IV | 0.021–0.052 | neurogenic (sympathetic) activity |
| V | 0.0095–0.021 | NO-dependent endothelial activity |
| VI | 0.005–0.0095 | non-NO-dependent endothelial activity |
