Our existence depends upon second law dS ⥠0, so life to sustain any Universe should start at low entropy not high as life and other dissipative structures need ...
BIOLOGICAL THERMODYNAMICS: A REVIEW Nitin Krishna Sai L1,G a r i m a V e r m a 1, A m r i t a P r e e t a m1 a n d A r v i nd K S ha r m a * 1 *
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AIM: 1. To review the evolution of life on the Earth, initial low entropy state of the
universe and the origin of structures . 2. The human heart (Biological system) is considered for the study on which the thermodynamic approach is used to generalize a relation between oxygen consumption and cardiac output.
WORK DONE BY HEART:
INTRODUCTION:
1. Universe started in a low entropy state and didn’t reach equilibrium yet and the low initial entropy was due to the low gravitational entropy of uniformly distributed matter. 2. There is general agreement that life on earth depends on the non equilibrium of the universe and requires free energy to live and life always dissipates energy and creates entropy in order to maintain its structure.
SOURCE OF EARTH’S FREE ENERGY—SUN
Assuming that the earth is in steady state but not in equilibrium,
(Fig.3)
HEART EFFICIENCY :
The definition of entropy, dSa,in = dQin / Tsun and dSa,out = Qout /Tearth
The heart can be viewed as a thermodynamic engine that transforms part of the expended power (P) into external power (W*f ).
According to 1st law,
above equation shows that the earth exports about 20 times entropy it receives from the sun and this decrease is compensated by the dissipative structures on the earth.
Average amount of blood flow (volume) per unit time:
Similarly for free-energy,
The net entropy flux of absorption of incoming solar photon and emission of infrared photons from the earth can be expressed as
The energy released in metabolic reactions, for a typical diet, is E=5.0 kcal/ (liter of O2) then Q changes to, Where r is the efficiency index [r = cη]
CARDIAC RESPONSE OUTPUT TO EXERCISE :
Similarly for free-energy,
By equating similar terms,
Thus, 95% of solar energy can be used to do work.
Exercise can be referred to as a vigorous work done continuously by the muscles. Exercise more than any other work taxes the regulatory ability of the cardiovascular system. Cardiac Index I is defined as :
(Fig.4)
(Fig.5)
CONCLUSION:
(Fig.1)
THERMODYNAMICS OF HEART:
The heart rate (heart beats per minute) is related to the cardiac output (volume of blood pumped by the heart per unit time) and the respiratory rate (rate of oxygen consumption).
Our existence depends upon second law dS ≥ 0, so life to sustain any Universe should start at low entropy not high as life and other dissipative structures need gradients to survive and hence the Earth is not in equilibrium. From first law, energy is conserved and hence ΔU = 0 and free energy is equal to free energy available to do work( -TΔS) and as long as ΔS ≥ 0, free energy will be flowing and life is possible. If either of T or ΔS tends to zero, ΔF also tends to zero and hence it is impossible to survive. Relation between heart’s beat rate and rate of oxygen consumption is linear that means as we do more work we will take in more amount of oxygen to supply enough energy, simultaneously ATP production also should take place at same pace and hence more oxygen is required.
REFERENCES:
1.
The rate of oxygen consumption by the heart,
2. 3.
ΩH = [Ω * c]
4.
The energy consumed by the heart,
5. 6. 7.
P = [E * c * Ω ] (Fig.2)
Charles H. Lineweaver, Chas A. Egan, Life, Gravity and the Second law of Thermodynamics, Physics of Life Reviews (2008), 225-242. Uehara, Mituo and Sakane, Kumiko Koibuchi, Thermodynamics of the Heart, www.intech.com W.A.Cramer and G.M.Soriano, Thermodynamics of Energy Transduction in Biological Membrane, Chapter one, BTOL-Bio-Energetics (2002). Kleidon A. Global Energy Balance. In: Jorgensen S, Editor. Encyclopedia of Ecology Elsevier; 2008. Donald T. Haynie, Biological Thermodynamics, Second Edition, Cambridge University press. Roger Penrose, The Road to Reality, First Edition, Jonathan Cape London. Blick, E. F. & Stein, P. D., Work of the Heart: A general Thermodynamic Analysis, Journal of Biomechanics, Vol. 10, No. 9, (Sept 1977) 589-595, ISSN 0021-9290.
