Most animals have excretory systems to eliminate toxic soluble wastes. Human beings have a urinary system, which is made up of the kidneys, ureters, urinary bladder, and urethra, which excretes the toxic soluble wastes. The kidneys extract the soluble wastes from the bloodstream, as well as excess water, sugars, and a variety of other compounds. Remaining fluid contains high concentrations of urea and other substances, including toxins. Urine flows through these structures: the kidney, ureter, bladder, and finally the urethra. Urine is produced by a process of filtration, reabsorption, and tubular secretion.
Urine is amber-yellowish to white in color and odorless. Urine is produced by a process of filtration, reabsorption, and tubular secretion of the nephron. Urine is composed of 95% water, urea, inorganic salts, uric acid, creatinine, ammonia, and broken-down blood pigments, including urochrome, which makes urine yellow, plus any unusual substances not reabsorbed into the blood. When the kidneys are malfunctioning blood, protein, and urinary casts can also be found in urine.