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Human Body Study

Ureters

A pair of thin muscular tubes carrying urine from the kidneys down to the bladder.

The urinary tract Two kidneys at top with ureters descending to a single bladder and urethra exiting below; a separate inset shows a nephron, the kidney's microscopic functional unit. Each label links to the article for that part. Nephron Kidneys Ureters Bladder Urethra The urinary tract — kidneys, ureters, bladder, urethra; the nephron is the kidney's microscopic functional unit.

What they do

Section titled “What they do”
  • Transport urine continuously, one ureter from each kidney.
  • Move it by peristalsis — waves of muscle contraction — rather than relying on gravity.
  • Prevent backflow — they enter the bladder at an angle, so a flap-like seal stops urine flowing back toward the kidneys.

Key idea

Section titled “Key idea”

The ureters are simple transport tubes; their one-way design protects the kidneys from backflow and infection. They are also where painful kidney stones can lodge.