3.2 Transport of Urine From the Kidney Through the Ureters

• What is the composition of urine expelled from the bladder?

  Same as fluid from collecting ducts
• What initiates peristaltic contractions in the ureters?

  Stretching of renal calyces by urine
• How long are the ureters in adults?

  25 to 35 centimeters
• What type of muscle is found in the walls of the ureters?

  Smooth muscle
• How are the ureters innervated?

  By sympathetic and parasympathetic nerves
• What enhances peristaltic contractions in the ureters?

  Parasympathetic stimulation
• What prevents backflow of urine from the bladder?

  Normal tone of the detrusor muscle
• What happens during micturition regarding the ureters?

  Pressure builds, allowing urine flow
• What is vesicoureteral reflux?

  Urine propelled backward into the ureter
• What can severe vesicoureteral reflux lead to?

  Enlargement of the ureters
• What is the ureterorenal reflex?

  Sympathetic reflex to constrict renal arterioles
• What happens when a ureter becomes blocked?

  Intense reflex constriction occurs
• What is the intravesicular pressure when the bladder is empty?

  About 0 centimeters of water
• What happens to intravesicular pressure as urine fills the bladder?

  Pressure rises with urine volume
• What is the pressure range when 30 to 50 milliliters of urine are collected?

  5 to 10 centimeters of water
• What occurs beyond 300 to 400 milliliters of urine in the bladder?

  Pressure rises rapidly
• What are micturition waves?

  Periodic acute increases in bladder pressure
• What causes micturition waves in the cystometrogram?

  The micturition reflex