LAWS OF THERMODYNAMICS 



173 



TABLE 7-3. (Con/in.) 



(7) Perfect osmotic system, osmotic 

 pressure difference due to dif- 

 ference of 1 mole of solute be- 

 tween the two solutions. Water 

 flow to equilibrium 



(8) Relaxation of stretched, elastic 

 tissue, per kcal of work done 



C. Free Energy-consuming Biological Reactions 



{ 1 ) Peptide bond formation in protein 

 synthesis: 

 R - COOH + NH, - /?' 



= R - CONH -- R' + H 2 



(2) Pyruvate or acetoacetate synthesis: 

 R - COOH + tf'COOH 



= R -COR' - COOH + H 2 



(3) Blood flow, per complete cycle 



(4) Man walking at 2 miles per hr 



AH 



(kcol/mole) 



ca -1000 



Af 

 (kcdl/mole) 



1.38 



1.0 



+ 3.0 



+ 16.0 

 ca +0.002 

 ca +0.010 



AS 

 (col/deg mole) 



+ 4.6 



ca +400 



(negative) 



(negative) 



(positive) 



(positive) 



Note: The values given under B and C are difficult to measure, depending as they do on pH, buffer. et< 

 and are subject to revision. For example in B (4), the hydrolysis of ATP in muscle, values of -9.2 and - 10.5 

 for A /-'have also been measured, and O. Meyerhof's (1927) experimental value of ±11 = - 12.0 is quoted ex- 

 tensively. The values change markedly with dielectric constant of the medium. (Some values have been 

 taken from the review by Wilkie, 1960.) 



metabolic heat loss, q', is numerically equal to the internal work done, 

 A.JF'in, . The rest of the metabolic heat loss, q' irr , is a result of irreversibility 

 in the chemical and physical processes (i.e., less than 100 per cent. The 

 efficiency is not 100%, as is often implied in disucssions of this sort). There- 

 fore 



and both q' irr and A9"' inl make appreciable contributions to q' . An estimate 

 of 8 for one specific case is given later. The value, 37 per cent, is probably 

 an upper limit to 8 , because it refers to a very efficient part of the human 

 being — the respiratory enzyme system. 



For purposes of cataloguing further, the metabolic heat loss, q', can be 

 considered to be the sum of two parts: (a) the basal metabolic heat, q' bm , 

 and (b) the extra heat, q' rx ; in excess of the basal metabolic heat. The 

 former is a minimum value, measured under carefully defined conditions of 

 rest. Thus (q' cx + q' hm ) is the heat loss (measurable) from the body during 

 exertion; and q' hm is the value measured when q' ex is zero. 



