The Urinary System

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The Urinary System

• Chapter 37.3

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Urinary System

• Function Helps maintain the homeostasis of body
  fluids.
• Structure
• 2 kidneys
• 2 ureters
• 1 urinary bladder
• 1 urethra

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The Kidney

• The kidneys are main organs of the urinary
  system.
• Function
• Filters and removes
  waste from blood
• Regulates body water
  volume, blood volume
  and blood pressure
• Regulates the amount
  of ions and salt in
  the body.
• Produces urine.

4

• Protein is broken down for energy in the body
  this releases ammonia (very toxic)
• Ammonia is converted into urea by the liver (less
  toxic)
• Some of the urea is removed by the skin in
  perspiration (sweating). Most is removed from
  the blood by the kidneys.

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Waste is removed in the kidney by Nephrons.

• 1 million nephrons per kidney
• Blood entering the nephron carries water,
  glucose, salt, vitamins, amino acids, ions, urea
  and waste.
• 1st step is filtration
• Small molecules, salt and water, and other waste
  are removed from the blood.
• 2nd step is reabsorption
• Important material (water, glucose, and salt) are
  reabsorbed into the blood.

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The remaining fluid is urine.

• Urine is water and solutes.
• Solutes excess elements, ions, salt, and
  vitamins, urea, toxic substances and drugs
• Approx. 1-2 Liters of urine produced a day.
• Ureters
• Carries urine from the kidneys to the bladder.
• About 25 cm long

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• Urinary Bladder
• Stores the urine
• Muscular sac on the bottom of the pelvic
  cavity.
• Average volume ½ Liter
• Max capacity ¾ Liter
• Urethra
• Passes urine out of the body
• Female approx 3-4 cm
• Male approx 18 cm