17677
The micro-circulation - the arterioles , capillaries , and venules - constitutes most of the area of the vascular system and is the site of the transfer of O , glucose , and enzyme substrates into the cells .
 location: O
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: O 
Answer:
 location: O