Final answer:
The combining form for renal pelvis is 'pyelo-' or 'pelvi-'. This structure collects urine from the calyces and conveys it through the ureters to the bladder, while also preventing urinary reflux.
Step-by-step explanation:
The combining form for the renal pelvis is 'pyelo-' or 'pelvi-'. This region in the kidney is where the calyces join the ureters, functioning as a funnel-like end to collect urine before it is transported through the ureter to the bladder. Located in the hilum of the kidney, the renal pelvis narrows down to become the ureter. It is vital in the process of urine transportation as it ensures that urine collected from the calyces drains into the ureter correctly. The ureters have an important physiological function, as they prevent reflux of urine from the bladder back into the ureter, which could significantly increase the risk of urinary tract infections (UTIs).