The renal pelvis.
D000818:Animals; D001834:Body Water / Q000378:metabolism; D006801:Humans; D007671:Kidney Concentrating Ability; D007679:Kidney Medulla / Q000033:anatomy & histology; D007682:Kidney Pelvis / Q000033:anatomy & histology / Q000502:physiology*; D007685:Kidney Tubules, Collecting / Q000502:physiology; D009119:Muscle Contraction