( ( Relation ( of ( between ( filtration ( , ( reabsorption ( ( secretion and ) excretion ) ) ) ) ) ) ) . )
(ROOT (NP (NP (NNP Relation)) (PP (IN of) (PP (IN between) (NP (NN filtration) (, ,) (NN reabsorption) (NN secretion) (CC and) (NN excretion)))) (. .)))
Relation of between filtration, reabsorption secretion and excretion.
(ROOT (S (NP (NP (DT The) (JJ main) (NNS functions)) (PP (IN of) (NP (NN epithelia)))) (VP (VBP are) (NP (NP (NN protection)) (PP (IN from) (NP (NP (DT the) (NN environment) (, ,) (NN coverage) (, ,) (NN secretion) (CC and) (NN excretion)) (, ,) (NP (NN absorption)) (, ,) (CC and) (NP (NN filtration)))))) (. .)))