Sentence:  In our attempt to interpret the emotions in their physiological and pathological range , we emphasized the importance of the degree of activity of the parasympathetic and sympathetic <WSD>divisions</WSD> of the hypothalamic system and their influence on the inhibitory and excitatory systems , respectively . 
Meaning of the word marked with <WSD> tags:  one of the portions into which something is regarded as divided and which together constitute a whole