14.1.4—Kidney gross structure

The kidney is organised into an outer cortex, an inner medulla and a central renal pelvis that leads to the ureter. This gross arrangement separates the region where blood is processed from the collecting route by which urine leaves the kidney.

Blood route and role

• The renal artery brings blood containing dissolved wastes and excess substances to the kidney.
• Processing occurs within the kidney; the renal vein carries the treated blood away.
• The cortex and medulla are regions of the kidney, not separate blood vessels or urine tubes.

Urine route and role

1. Urine formed within the kidney drains towards the renal pelvis.
2. The ureter carries urine from each kidney to the bladder for temporary storage.
3. The urethra carries urine from the bladder to the outside of the body.

The renal pelvis is therefore a collection and routing region; the ureter and urethra are transport/outflow structures.

Trace blood and urine as separate routes: the renal artery does not carry urine, and the renal vein does not carry filtrate. This card stays at whole-kidney anatomy; nephron microstructure, osmoregulation mechanisms and test-strip detection belong to later cards.