Diaphragm Kidney 1. Excretion Ureter 2. Pathway for excretion Bladder Urethra The paired kidneys form a filtrate of the blood that is modified by reabsorption and secretion; urine designated for excretion moves along the ureters to the bladder.The paired kidneys form a filtrate of the blood that is modified by reabsorption and secretion; urine designated for excretion moves along the ureters to the bladder. 1. Excretion 2. Pathway for excretion