Final answer:
The renal pelvis is the funnel-like end of a ureter in the kidney where urine collects before it is transported through the ureter to the bladder. It serves as a vital reservoir in the excretory process, collecting urine from the calyces and directing it toward the ureter.
Step-by-step explanation:
The renal pelvis is a funnel-like end of a ureter located in the region called the hilum of the kidney. Internally, the kidney is divided into three regions: an outer cortex, a medulla in the middle, and the renal pelvis. The renal cortex contains numerous functional units called nephrons, which are responsible for filtering blood and generating urine. The medulla consists of conical structures known as renal pyramids, and the tips of these pyramids point toward the renal pelvis. The urine collected from the nephrons passes through the collecting ducts into the calyces which are cup-like structures. These calyces merge to form the renal pelvis, which collects the urine and transports it through the ureter to eventually reach the urinary bladder. The ureter arises from the renal pelvis and its passage is not simply gravity-driven but involves peristaltic movements which aid in the transport of urine.
The hilum is where blood vessels, nerves, and the ureter enter and exit the kidney, and the renal pelvis in this region collects and channels urine into the ureter. The ureter then funnels the urine into the urinary bladder. It is essential in the excretory system, acting as a reservoir before urine is discharged from the body.