Why do urea and Ammonia levels increase after filtration occurs in the human body?

Question

The filter being glomerulus

Answer 1

posted by some dude on a forum:

Are you talking about the filtration at the level of the nephron?
If so, then the answer is simple: after filtration, along the nephron, through processes of secretion and excretion ureea and ammonia and other stuff is dumped into the nephron

Apparently, someone asked the EXACT same question as you. hmm..weird. =)