Title: Organisms live at far-from-equilibrium with their surroundings while maintaining homeostasis, importing exergy and exporting entropy

Authors: Cennet Yildiz; Volkan Adem Bilgin; Bayram Yılmaz; Mustafa Özilgen

Addresses: Department of Food Engineering, Faculty of Engineering, Yeditepe University, Kayisdagi Cad., 34755, Istanbul Turkey ' Faculty of Medicine, Yeditepe University, Yeditepe University Hospital, Istanbul Turkey ' Faculty of Medicine, Yeditepe University, Yeditepe University Hospital, Istanbul Turkey ' Department of Food Engineering, Faculty of Engineering, Yeditepe University, Kayisdagi Cad., 34755, Istanbul Turkey

Abstract: Organisms live at far-from thermodynamic equilibrium with their surroundings. They import exergy, export entropy and maintain constancy of their vital internal physiological constituents via homeostasis. Calculations based on the data collected from literature showed that homeostasis helps organisms to save exergy in living processes. On the other hand, temperature homeostasis, which serves to maintain constant body temperature in endotherms is achieved by consuming exergy. The daily exergy expenditure rate of an animal depends on the rate of its metabolism, body weight and the nutritional exergy up take. While an endothermic (homeothermic) mammal, which spends 30% of its time on the field active metabolic mode and the rest of the day in resting mode needs 5.9 g of meat/kg day to satisfy its exergy need; an ectothermic reptile with the same field active and resting metabolic pattern would need 0.5 kg of meat to satisfy its daily exergy need.

Keywords: temperature homeostasis; mass homeostasis; energy homeostasis; endothermy; exergetic cost.

DOI: 10.1504/IJEX.2020.106457

International Journal of Exergy, 2020 Vol.31 No.3, pp.287 - 301

Received: 03 Jul 2019
Accepted: 26 Oct 2019
Published online: 07 Apr 2020 *

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