512 



ANIMAL BIOCHEMISTRY 



relaxed 

 muscle 



Glycogen 



lactate 



creatine 



contracted 

 muscle + HPO4 



creatine 



phosphate 



FIGURE 21 -T. The overall energ} transfers in muscle contraction. 



the supply of ATP for proper muscle function and operates through 

 the reversible reaction 



CH3 



CHa 



ADP + H2N+=C— N— COO- <- > ATP + H2N+=C— N— COO" 



kinase 



HN— P03= 



creatine phosphate 



NH2 



creatine 



Energy Allowances 



As was indicated in Table 21-9, the energy needs depend upon the 

 muscular activity as well as on the size, age, sex, etc., of animals. Hu- 

 man beings at work expend energy at the rates shown in the table 

 with each of their occupations corresponding to one of the variotis 

 degrees of exercise. Average values for people in different types of 

 jobs are shown in Table 21-10. These allowances must be adjusted for 

 individual differences according to the principles outlined earlier. 

 See the Appendix for additional data. Activities similar to these in 

 level of exertion have similar energy allowances. Note that the basal 

 metabolic rate depends on daily muscular activity to some extent as 



