The Urinary System Functions of the Urinary System

The Urinary System

Functions of the Urinary System n n Elimination of waste products n Nitrogenous wastes n Toxins n Drugs Regulate aspects of homeostasis n Water balance n Electrolytes n Acid-base balance in the blood n Blood pressure n Releases erythropoietin (stimulates RBC production) n Produces an active form of Vitamin D

Urinary System • Two Kidneys – Perform all filtering functions (but not excretion) • Two Ureters – Bring urine from Kidneys to Urinary Bladder • Urinary Bladder – Holds Urine until excretion – Can stretch • Urethra – Moves urine from bladder to outside of body

kidneys Organs of the Urinary System ureters urinary bladder urethra

Kidney Location Against the dorsal body wall (retroperitoneal) n Superior dorsal region (T 12 to L 3) n The right kidney is slightly lower than the left (due to position of the liver) n *An adrenal gland sits atop each kidney

Kidney Anatomy (External) n Renal hilum (hilus- singular) n A medial indentation where several structures enter or exit the kidney (ureters, renal artery, renal vein)

Coverings of the Kidneys n Renal Capsule n n Perirenal fat capsule n n Surrounds each kidney Surrounds the kidney and cushions against blows Renal fascia n Outermost capsule that helps hold the kidney in place against the muscles of the trunk wall

Regions of the Kidney(Internal) Renal cortex—outer region n Renal medulla—inside the cortex n Renal pelvis—inner collecting tubes, lead to the ureter n

Internal Kidney Structures n n n Renal or medullary pyramids -triangular shaped striped regions of tissue in the medulla Calyx(ces) -cup-shaped structures, drain urine from pyramids into pelvis Renal columns extensions that separate the pyramids in the medulla

Blood Supply n n n One-quarter of the total blood supply of the body passes through the kidneys each minute Approximately 200 quarts of blood are processed every 24 hours Approximately 2 quarts of fluid are removed during that time