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相关概念视频

Production Efficiency01:01

Production Efficiency

Net production efficiency (NPE) is the efficiency at which organisms assimilate energy into biomass for the next trophic level. Due to low metabolic rates and less energy spent on thermoregulatory processes, the NPE of ectotherms (cold-blooded animals) is 10 times higher than endotherms (warm-blooded animals).
Trophic Efficiency00:46

Trophic Efficiency

Trophic level transfer efficiency (TLTE) is a measure of the total energy transfer from one trophic level to the next. Due to extensive energy loss as metabolic heat, an average of only 10% of the original energy obtained is passed on to the next level. This pattern of energy loss severely limits the possible number of trophic levels in a food chain.
Entropy within the Cell01:22

Entropy within the Cell

A living cell's primary tasks of obtaining, transforming, and using energy to do work may seem simple. However, the second law of thermodynamics explains why these tasks are harder than they appear. None of the energy transfers in the universe are completely efficient. In every energy transfer, some amount of energy is lost in a form that is unusable. In most cases, this form is heat energy. Thermodynamically, heat energy is defined as the energy transferred from one system to another that is...
Energy Losses in Transformers01:21

Energy Losses in Transformers

In an ideal transformer, it is assumed that there are no energy losses, and, hence, all the power at the primary winding is transferred to the secondary winding. However, in reality,  the transformers always have some energy losses, and, hence, the output power obtained at the secondary winding is less than the input power at the primary winding due to energy losses.
There are four main reasons for energy losses in transformers.
The first cause can be  the high resistance of the copper windings...
Chambers of the Heart01:16

Chambers of the Heart

The human heart is a complex organ made up of four chambers: the right and left atria and the right and left ventricles. These internal chambers are separated by partitions known as the interatrial and interventricular septa. The exterior of the heart features a groove known as the coronary sulcus that demarcates the atria from the ventricles, while the anterior and posterior interventricular sulci distinguish between the two ventricles.
Deoxygenated blood from the body is received in the right...
Lateralization01:28

Lateralization

Brain lateralization refers to the division of mental processes and functions between the two hemispheres of the brain, a phenomenon that optimizes neural efficiency and underpins complex abilities in humans. This specialization allows each hemisphere to perform tasks where it has a comparative advantage, facilitating more refined cognitive capabilities across different domains.

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相关实验视频

Updated: Jul 25, 2026

Assessment of Cardiac Function and Energetics in Isolated Mouse Hearts Using 31P NMR Spectroscopy
11:38

Assessment of Cardiac Function and Energetics in Isolated Mouse Hearts Using 31P NMR Spectroscopy

Published on: August 31, 2010

在人类左心室的能量转换效率.

T Kameyama1, H Asanoi, S Ishizaka

  • 1Second Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Japan.

Circulation
|March 1, 1992
PubMed
概括

尽管心脏功能发生了变化,但左心室的机械效率仍然稳定,只要收缩能力没有严重受损. 这项研究阐明了为什么机械效率对性能变化不敏感.

科学领域:

  • 心血管生理学心血管生理学
  • 心脏机械学 心脏机械学
  • 心脏衰竭研究研究

背景情况:

  • 左心室机械效率是心脏性能的一个关键指标.
  • 之前的研究指出,即使在心力衰竭中,机械效率也令人惊地稳定.
  • 机械效率对性能变化的不敏感性需要进一步研究.

研究的目的:

  • 用压力-体积面积 (PVA) 概念分析人类左心室的机械效率.
  • 为了澄清观察到机械效率对性能变化的不敏感性背后的原因.
  • 研究心肌氧消耗 (MVO2),PVA和外部工作之间的关系.

主要方法:

  • 在11名患有不同收缩状态的患者中确定了MVO2-PVA关系和外部作用.
  • 计算PVA/MVO2效率,工作效率和整体机械效率.
  • 构建左心室压力-体积循环和评估的末缩压力-体积关系 (Ees) 斜率.

主要成果:

  • 压力加载增加了外部工作,PVA和MVO2,降低了工作效率,但增加了PVA/MVO2效率.
  • 这些效率的相反变化保持了整体机械效率的不变.
  • PVA/MVO2效率与Ees相反相关,而工作效率与Ees线性相关.

更多相关视频

Measurement of Energy Metabolism in Explanted Retinal Tissue Using Extracellular Flux Analysis
10:19

Measurement of Energy Metabolism in Explanted Retinal Tissue Using Extracellular Flux Analysis

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Real-Time Analysis of Bioenergetics in Primary Human Retinal Pigment Epithelial Cells Using High-Resolution Respirometry
09:16

Real-Time Analysis of Bioenergetics in Primary Human Retinal Pigment Epithelial Cells Using High-Resolution Respirometry

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相关实验视频

Last Updated: Jul 25, 2026

Assessment of Cardiac Function and Energetics in Isolated Mouse Hearts Using 31P NMR Spectroscopy
11:38

Assessment of Cardiac Function and Energetics in Isolated Mouse Hearts Using 31P NMR Spectroscopy

Published on: August 31, 2010

Measurement of Energy Metabolism in Explanted Retinal Tissue Using Extracellular Flux Analysis
10:19

Measurement of Energy Metabolism in Explanted Retinal Tissue Using Extracellular Flux Analysis

Published on: January 7, 2019

Real-Time Analysis of Bioenergetics in Primary Human Retinal Pigment Epithelial Cells Using High-Resolution Respirometry
09:16

Real-Time Analysis of Bioenergetics in Primary Human Retinal Pigment Epithelial Cells Using High-Resolution Respirometry

Published on: February 3, 2023

结论:

  • 左心室的机械效率在很大程度上不受负载和无otropic条件的变化的影响.
  • 这种稳定性持续下去,除非左心室收缩率明显下降.
  • PVA概念有助于解释不同心脏状态的机械效率的稳定性.