A novel method for estimating the entropy generation rate in a human body

Rahman, Mohammad Azizur

doi:10.2298/tsci0701075r

Cited by 37 publications

(30 citation statements)

References 4 publications

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“…According to MREG, the natural death of BS is presumed to occur when the whole BS generates fixed amount entropy per unit mass over life span just like Rubner's hypothesis on fixed energy expenditure. MREG theory is supported by the works of Batato et al [17], Aoki [18,19,20] and Rahman [21] among others, who calculated the entropy generation rate for humans and found it to be within the same order of magnitude as Hershey and Wang and Silva and Annamalai. Higher metabolic efficiency () represents better use of nutrients in maintaining the healthy state of organs within BS.…”

Section: Modified Reg (Mreg)mentioning

confidence: 86%

Entropy Stress and Scaling of Vital Organs over Life Span Based on Allometric Laws

Annamalai

Silva

2012

Entropy

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Past theories on total lifetime energy expenditures and entropy generation in biological systems (BS) dealt with whole systems, but the recent literature suggests that the total metabolic rate of a BS, body (W) is a sum of product of specific metabolic rate k,m (W/kg of organ k) of each vital life organ, k {k = brain, heart, kidney and liver, or abbreviated as BHKL, and rest of the organ mass (R)} and mass of each organ k (m k ). Using this hypothesis, Kleiber's law on metabolic rate of BS ( body ) for animals of different sizes was validated. In this work, a similar procedure is adopted in estimating total entropy generation rate of whole human body ( body , W/K) as a sum of product of specific entropy generation rate for each organ, k , m (W/{K kg of organ k·}) and the organ mass at any given age (t). Further integrating over life span for each organ (t life ), the lifetime specific entropy generated by organ k, k,m,life (J of organ k/ {K kg organ k}) is calculated. Then lifetime entropy generation of unit body mass, body,M,life (J/{K kg body mass·}) is calculated as a sum of the corresponding values contributed by all vital organs to unit body mass and verified with previously published literature. The higher the k,m,life , the higher the entropy stress level (which is a measure of energy released by unit organ mass of k as heat) and the irreversibility within the organ, resulting in faster degradation of organ and the consequent health problems for the whole BS. In order to estimate k (W/K of organ k), data on energy release rate ( ) is needed over lifetime for each organ. While the Adequate Macronutrients Distribution Range (AMDR)/Adequate Intake (AI) publication can be used in estimating the energy intake of whole body vs. age for the human body, the energy expenditure data is not available at organ level. Hence the k,m,life was computed using existing allometric laws developed for the metabolism of the organs, the relation between OPEN ACCESSEntropy 2012, 14 2551 the m k of organ and body mass m B , and the body mass growth data m B (t) over the lifetime. Based on the values of k, m, life , the organs were ranked from highest to lowest entropy generation and the heart is found to be the most entropy-stressed organ. The entropy stress levels of the other organs are then normalized to the entropy stress level (NES H ) of the heart. The NES H values for organs are as follows: Heart: 1.0, Kidney: 0.92, Brain: 0.46, Liver: 0.41, Rest of BS: 0.027. If normalized to rest of body (R), NES R , heart: 37, Kidney: 34, Brain: 17, Liver: 15, Rest of BS: 1.0; so heart will fail first followed by kidney and other organs in order. Supporting data is provided.

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Section: Modified Reg (Mreg)mentioning

confidence: 86%

Entropy Stress and Scaling of Vital Organs over Life Span Based on Allometric Laws

Annamalai

Silva

2012

Entropy

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“…Although the entropy production and destroyed exergy were already calculated for the whole body [5,6,15,17] and for the lung [16] during physical activities, the exergy efficiency of this organ has not yet been discussed. In the present work, destroyed exergy and exergy efficiency are calculated as a function of altitude and intensity of physical activity.…”

Section: Introductionmentioning

confidence: 99%

The effect of altitude and intensity of physical activity on the exergy efficiency of respiratory system

Henriques¹,

Mady²,

Neto³

et al. 2014

Int. J. Thermo

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The effect of altitude on exercise performance of lowlanders has long been discussed, but it is still unclear whether the performance reduction is related to inefficiency of the respiratory system, body tissues or both. In the present work, exergy analysis was applied to the human body in order to compare its exergy efficiency under basal conditions and during physical activity at sea level and high altitudes for different periods of acclimatization. Two control volumes were analyzed: respiratory system and human body as a whole. Data concerning mass and energy balances of the body and respiratory system were obtained from models available in the literature, which were modified based on medical literature to simulate the responses to physical activity at high altitude for different periods of acclimatization. The results indicated that the respiratory system exergy efficiency is reduced at high altitudes and under physical activity, while exergy efficiency of the body increases for both parameters, which may indicate that the discomfort reported at high altitudes is mostly related to the respiratory system than to the other ones. Concerning the acclimatization period, its influence was more pronounced on the respiratory system.

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“…Segundo Rahman (2007), no período de um dia, a entrada de massa (alimentos, líquidos e ar inspirado) equivale à saída de massa (fezes, urina, ar expirado e vaporização pela pele). Se o indivíduo não estiver engordando ou emagrecendo, ou seja, se não houver acúmulos, a massa do corpo não deve se alterar com o passar de um dia.…”

Section: Balanços Diários De Massa Energia E Exergiaunclassified

“…A Figura 2.24 indica os valores obtidos por Rahman (2007). No entanto, foram realizadas algumas alterações nos seguintes termos:…”

Section: Balanços Diários De Massa Energia E Exergiaunclassified

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Desempenho termodinâmico do corpo humano e seus subsistemas: aplicações à medicina, desempenho esportivo e conforto térmico.

Mady¹

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A novel method for estimating the entropy generation rate in a human body

Cited by 37 publications

References 4 publications

Entropy Stress and Scaling of Vital Organs over Life Span Based on Allometric Laws

Entropy Stress and Scaling of Vital Organs over Life Span Based on Allometric Laws

The effect of altitude and intensity of physical activity on the exergy efficiency of respiratory system

Desempenho termodinâmico do corpo humano e seus subsistemas: aplicações à medicina, desempenho esportivo e conforto térmico.

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