Final answer:
The ascent of the kidneys is prevented by their anatomic position, attachments to adjacent organs and structures, ureteric attachment and function, and physiological mechanisms that regulate blood flow and pressure such as vasoconstriction, and hormonal control through renin, angiotensin II, and aldosterone.
Step-by-step explanation:
The ascent of the kidneys is stopped by several physiological barriers and functional mechanisms. Anatomically, the kidneys are held in place by surrounding tissues and organs, and structurally reinforced by the renal fascia and fat. They are located in the retroperitoneal space underneath the diaphragm, preventing them from moving upward. Additionally, the kidneys are connected to the rest of the urinary system, namely to the ureters, which effectively anchor the kidneys. These ureters propel urine to the bladder through peristalsis, ensuring no backflow into the kidneys, while the bladder's oblique course of the ureters forming a one-way valve prevents reflux.
On a functional level, the kidneys rely on tight regulation of blood flow and pressure to perform their duties of filtration and water recovery. The sympathetic nervous system can induce vasoconstriction, while the production of renin, angiotensin II, and aldosterone serves to ensure appropriate blood volume and pressure. This intricate interplay of systems helps to maintain the kidneys in their proper location, contributing to the cessation of any potential ascent.