title: New valve-mechanical model of urinary tract function: the theory of biological dual valves.
abstract: BACKGROUND
  Until now, peristalsis has been the only known method of urine transport. The main objective of this paper was to study urinary tract function - especially the upper urinary tract, the ureter - from a new mechanical point of view. The physical (physical dual valves) and biological basis (biological dual valves) of a new functional model is presented based on previous observations and knowledge.
  
  
  METHODS
  A review of the literature was performed, with special emphasis on ureter motility.
  
  
  RESULTS
  After analyzing the anatomy and physiology of the urinary tract, complemented by basic physical observations, the authors have developed a new valve-mechanical model of urinary tract function. A comprehensive mechanical hypothesis is also presented, integrating the role of peristalsis.
  
  
  CONCLUSIONS
  The authors believe that the new theory enhances previous knowledge. From a structural point of view, the urinary tract may be considered to consist of dualvalves. The dual-valve mechanism combined with peristalsis allows better explanation of the function of the upper urinary tract in particular. The main conclusion is that the flow in the urinary tract must be studied integrally within the body. This new theory does not contradict well-known and acknowledged theories, and moreover, it may help solve certain medical problems.
authors.affiliation: Lausitzer Seenland Klinikum, Hoyerswerda, Germany.
authors.forename: Arpad
authors.initials: A
authors.lastname: Dani
authors.affiliation: Faculty of Mechanical Engineering, Szent Istvan University, Gödöllő, Hungary.
authors.forename: Peter
authors.initials: P
authors.lastname: Szendrő
keywords: new biological model; peristalsis; urinary tract physiology