Final answer:
The renal medulla is the inner portion of the kidney where the collecting ducts, situated within the renal pyramids, gather urine and drain it into the renal pelvis and ureter.
Step-by-step explanation:
The inner portion of the kidney, which consists of collecting tubules that empty into the renal pelvis, is known as the renal medulla. The medulla is organized into triangular structures called renal pyramids. These pyramids contain the collecting ducts that receive urine from the nephrons and transport it to the renal pelvis, eventually leading to the ureter and urinary bladder.
The renal cortex is the outer region of the kidney, housing the nephrons responsible for filtering blood and processing urine. Meanwhile, the renal medulla is composed of the renal pyramids and the renal papillae, where the collecting ducts are found. The collecting ducts converge as they pass through the medulla, at the apex of the renal papillae, and enter the minor calyces. These minor calyces then join to form major calyces, ultimately draining into the renal pelvis.