The Control of Respiration and Body 

 Temperature 



(a) RESPIRATION 



As with other rhythmic motor activities, the control of respir- 

 atory movements involves two sorts of problem. The first is 

 concerned with co-ordination of the many different muscles 

 which produce the respiratory movements. Each of these can 

 vary the strength of its contraction and must function at a par- 

 ticular phase of the cycle, otherwise the whole system would 

 become disco-ordinated and ineffective. The second problem is 

 one of regulation, i.e., the way in which the respiratory mechan- 

 ism adjusts to changes in environmental conditions both within 

 and outside the body. This usually involves modifications of the 

 rhythm and ventilation volume. It is difficult always to separate 

 these two problems but once it has been established how the 

 rhythm is produced, then mechanisms which modify the extent 

 and frequency of its action can be more readily understood. 



When considering the determination of rhythmic muscular 

 activities the nervous system can be considered in two parts, the 

 central nervous system and the peripheral input from sense 

 organs. That these two cannot be independent is clear, but the 

 precise ways in which they interact and their relative importance 

 are variable. Three main theories (fig. 24) have been proposed 

 for respiration : (i) The rhythmic movements are determined and 

 controlled entirely by the nature of the sensory inflow to the 

 c.n.s. This reflex view supposes that all movements result from 

 stimuli arising from preceding movements and is no longer 

 strongly held for respiration, as it omits the rhythmic properties 



