[Solved] Which structure receives the penis for delivery of sperm? A) A B) B C) C D) D Nephron: The structural and functional unit of the kidney. Kidney: A pair of organs in the urinary system that filter waste products from the blood and excrete them in urine. Microscopic Units: Small units of measurement typically used to describe dimensions of cells and microorganisms, not visible to the naked eye. Calyx: The cuplike division of the kidney pelvis.