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Related Concept Videos

Line Loss01:10

Line Loss

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The different configurations of source-load connections include wye (star) and delta connections. The relationship between line and phase voltages and currents varies depending on the configuration. When the source is supplying power, it is transmitted through the wires to the load, and during this transmission, some power is absorbed by the wires, leading to line loss.
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Reducing Line Loss01:18

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In a three-phase circuit, line loss is an indicator of energy dissipated as heat due to the resistance of transmission lines. To address this, incorporating transformers into the system—a step-up transformer at the source and a step-down transformer at the load—is a strategic solution. Two three-phase transformers are introduced to improve this.
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Major Losses in Pipes01:28

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Energy Losses in Transformers01:21

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Related Experiment Video

Updated: Feb 14, 2026

Author Spotlight: Studying Neuromuscular Responses and Motor Neuron Plasticity in Neurodegenerative Diseases
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Phrenic motor neuron loss in aged rats.

Matthew J Fogarty1,2, Tanya S Omar1, Wen-Zhi Zhan1

  • 1Department of Physiology and Biomedical Engineering, Mayo Clinic , Rochester, Minnesota.

Journal of Neurophysiology
|February 8, 2018
PubMed
Summary

Aging leads to diaphragm muscle loss (sarcopenia) due to a significant decrease in phrenic motor neurons (PhMNs). This age-related denervation affects larger motor units, impacting muscle force and function.

Keywords:
neuro-motor controlphrenic motor neuronsarcopenia

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Area of Science:

  • Physiology
  • Neuroscience
  • Gerontology

Background:

  • Sarcopenia, the age-related loss of muscle mass and strength, affects various muscles, including the diaphragm.
  • Previous research indicated diaphragm muscle sarcopenia in aged rodents is linked to specific muscle fiber atrophy and reduced force.
  • The underlying cause of diaphragm sarcopenia, specifically the role of phrenic motor neurons (PhMNs), remained unexplored.

Purpose of the Study:

  • To test the hypothesis that sarcopenia of the diaphragm muscle is caused by an age-related loss of phrenic motor neurons.
  • To quantify the number and assess the morphology of PhMNs in young versus old Fischer 344 rats.
  • To investigate age-related changes in PhMN size and their potential link to specific muscle fiber types.

Main Methods:

  • Fischer 344 rats of two age groups (6 months and 24 months) were used.
  • Phrenic motor neurons were retrogradely labeled and visualized using confocal microscopy.
  • Quantitative analysis included counting PhMNs and measuring the surface area of their soma and proximal dendrites.

Main Results:

  • A significant reduction in PhMNs was observed in older rats (22% fewer) compared to younger rats.
  • Older rats exhibited decreased somal surface area (19% reduction) and dendritic surface area (21% reduction) of PhMNs.
  • The age-associated loss of PhMNs disproportionately affected larger neurons, suggesting denervation of specific motor units.

Conclusions:

  • The study provides evidence for a substantial loss of phrenic motor neurons in aged rats, supporting the hypothesis of denervation-induced sarcopenia.
  • Age-related changes in PhMN number and morphology indicate a loss of neuronal heterogeneity, impacting diaphragm muscle function.
  • These findings suggest that the denervation of larger, fatigable motor units contributes to age-related diaphragm muscle weakness and impaired airway clearance.