Urinary System

• Kidneys


  • Filter gallons of fluid from the bloodstream
  • Process the filtrate, allowing wastes and excess ions to leave the body in urine while returning needed substances to the blood in just the right proportions
• Organs of the urinary system


  • Kidneys
  • Ureters
  • Urinary bladder
  • Urethra
• Kidney


  Pair of small dark red organs that had a kidney-bean shape. Adult kidney is about 12cm long & 6cm wide and 3 cm thick. It lies against the dorsal body wall, right at the border at the thoracic and lumbar region (which gives them a little bit of protection from the lower part of the rib cage)
• Parts of the kidney


  • Renal cortex
  • Renal medulla
  • Renal pelvis
• Ureters


  Two slender tubes each about 25 to 30 cm long, Passage way to carry urine from the kidney to the bladder
• Ureters


  • Smooth muscle in the walls to propel urine to the bladder (similarly to the esophagus propelling food from the mouth to the stomach)
• Urinary bladder


  Smooth, collapsible muscular sac; Made of transitional epithelium (allows for stretching) and reticular connective tissue (allows for it to not collapse when empty)
• Layers of the urinary bladder


  • Three layers of smooth muscle
• Urethra


  Thin-walled tube that carries urine from the bladder to the outside of the body; it also has smooth muscles in its walls to carry the flow of urine in correct the direction
• Sphincters of the urethra


  • Internal urethral sphincter
  • External urethral sphincter
• For females, the urethra is for urine only. But for males it is for both urine and semen (part of the reproductive system)