The kidney is composed of about 1 million functional units, called nephron
glomerular capsule (Bowman’s capsule) as a network of arterial capillaries

the nephron is about 3 cm long and its parts:

1) the proximal convoluted tubule 2) the descending loop of Henle 3) the ascending loop of Henle 4) the distal convoluted tubule 5) the collecting tubule and duct