First, it pulls {HEAD ~ liquid water} from {TAIL ~ the flow channels}, keeping them free from blockage 
from
First , it pulls { HEAD ~ liquid water } from { TAIL ~ the flow channels } , keeping them free from blockage
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH