Urinary System
The kidneys, ureters, bladder, and urethra, which filter blood, remove nitrogenous waste as urine, and regulate fluid volume, electrolytes, blood pressure, and pH.
Flow order: kidney, ureter, bladder, urethra. The hormone ADH increases water reabsorption to concentrate urine when the body is dehydrated, and the kidneys also release erythropoietin, which tells bone marrow to make red blood cells.