In a nephron, ultra-filtration occurs in the renal corpuscle (glomerulus + Bowman’s capsule). Glomerular filtration of blood is also known as ultra filtration. It is a non-selective process and filtration is so fine that every component of plasma (water, glucose, amino acids, urea, etc) except proteins pass into the Bowman’s capsule. The epithelium of renal corpuscle has tiny filtration slits (also called slit pores) that help in ultra-filtration. This process ensures that only waste products and excess water are removed from the body and it also helps to concentrate the urine.