The three distinct processes involved in the production of urine
are :
Glomerular filtration : Filtration of blood in
glomerulus capillaries across filtration membrane that filters
substances in blood except proteins and blood cells.
Selective reabsorption : Nutrients, water and
certain ions are selectively reabsorbed from segments of renal
tubules into the peritubular capillaries.
Tubular secretion : Harmful nitrogenous waste
products such as urea, ammonia, H+ ions, drugs are secreted from
peritubular capillaries into tubule lumen.