The Urinary System

Functions of the Urinary System Elimination of waste products Nitrogenous wastes Toxins Drugs Regulate aspects of homeostasis Water balance Electrolytes Acid-base balance in the blood Blood pressure Releases erythropoietin

Urinary System Two Kidneys Two Ureters Urinary Bladder Urethra 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

Organs of the Urinary System kidneys ureters Organs of the Urinary System urinary bladder urethra

Kidney Location Against the dorsal body wall (retroperitoneal) Superior dorsal region (T12 to L3) The right kidney is slightly lower than the left (due to position of the liver) *An adrenal gland sits atop each kidney

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

Coverings of the Kidneys Renal Capsule Surrounds each kidney Perirenal fat capsule Surrounds the kidney and cushions against blows Renal fascia 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 Renal medulla—inside the cortex Renal pelvis—inner collecting tubes, lead to the ureter

Internal Kidney Structures 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

Figure 15.2b

Blood Supply One-quarter of the total blood supply of the body passes through the kidneys each minute