Which material is secreted into the fi ltrate in the kidney tubule? A. H 2 O B. urea C. Na + D. albumin
Option B. Urea is secreted into the filtrate in the kidney tubule. Urea (a waste product) is lipid soluble so can passively pass out of the fi ltrate into the tubule cells. It is secreted back into the fi ltrate to effect its excretion.
