The =urinary organs= (Organa uropoiëtica) are the kidneys, ureters,
bladder, and urethra. The =kidneys= are the glands which secrete the
urine; they are red-brown in color, and are situated against the dorsal
wall of the abdomen, being in most animals almost symmetrically placed
on either side of the spine. The =ureters= are tubes which convey the
urine to the =bladder=. The latter is an ovoid or pyriform sac, situated
on the pelvic floor when empty or nearly so; it is a reservoir for the
urine. The urine accumulates in the bladder until that organ is full,
and is then expelled through the =urethra=.
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