Considering the attached figure; the functional area of the kidney at letter b; is the Renal pyramid.
Kidney pyramid or renal pyramid consist of tubules that transport urine from the cortical, or outer part of the kidney, where the urine is produced, to the calyces, or cup-shaped cavities where the urine collects before passing to the bladder through the ureter.
Kidney pyramid or renal pyramid consist of tubules that transport urine from the cortical, or outer part of the kidney, where the urine is produced, to the calyces, or cup-shaped cavities where the urine collects before passing to the bladder through the ureter.