Final answer:
The outer layer of the kidney is called the renal capsule. The kidney also features an outer cortex and a middle medulla internally, with the renal capsule protecting the outermost part of the kidney's structure.
Step-by-step explanation:
The outer layer of the kidney is called the renal capsule. The kidneys have three main external layers: the outermost renal fascia, the middle perirenal fat capsule which helps to anchor the kidneys in place, and the third, innermost layer being the renal capsule. Internally, there are also three layers within the kidney: the outer cortex, the middle medulla, and the inner renal pelvis. The renal cortex, which contains all of the nephrons—the functional units of the kidney—is granular in appearance and is where most of the filtration process occurs. The medulla, consisting of the renal pyramids and renal columns, supports the cortex and is involved in the collection and transport of urine. Lastly, the renal pelvis collects the urine and channels it into the ureters, which then lead to the urinary bladder.