Comprehensive Overview of the
Urinary System
Urinary System Notes
Urinary System Organs
Kidneys - major excretory organs
Ureters - transport urine from kidneys to urinary bladder
Urinary bladder - temporary storage reservoir for urine
Urethra - transports urine out of the body
Kidney Anatomy
Retroperitoneal, in the superior lumbar region; around T12 to L5
Right kidney is crowded by the liver and is lower than the left kidney
Adrenal (suprarenal) gland atop each kidney
Convex lateral surface, concave medial surface
Ureters, renal blood vessels, lymphatics, and nerves enter and exit at
the hilum
Internal Anatomy
Renal cortex - granular-appearing superficial region
Renal medulla - composed of cone-shaped medullary (renal) pyramids,
separated by renal columns (inward extensions of cortical tissue)
Papilla - tip of the pyramid; releases urine into minor calyx
Lobe - medullary pyramid and its surrounding cortical tissue;
approximately 8 per kidney
Renal pelvis - funnel-shaped tube continuous with the ureter
Minor calyces - drain the pyramids at the papillae
Major calyces - collect urine from the minor calyces and empty it into
the renal pelvis
Urine flow: Renal pyramid → minor calyx → major calyx → renal pelvis
→ ureter
Blood and Nerve Supply
Kidneys cleanse the blood and adjust its composition; they have a rich
blood supply.
Renal arteries deliver approximately 1/4 (1200 ml) of the cardiac output
to the kidneys each minute.
Arterial flow into and venous flow out of the kidneys follow similar
paths.
Nerve supply via sympathetic fibers from the renal plexus.
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