Excretory System

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Excretory System

• Chapter 38-3

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• Kidney
• filters blood
• salt and water absorption
• located behind the intestines

• Ureter
• carries urine from kidney to bladder

• Bladder
• holds urine

• Urethra
• carries urine from bladder out of body

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Nephron- functional unit of kidney
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Kidneys Maintain Homeostasis

• Homeostasis
• process of maintaining a stable internal
  environment
• Kidneys filter the blood to remove waste (sugars,
  amino acids, salts, drugs)
• Maintains water and salt balance in the blood
• Maintains pH

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How long does it take the kidney to filter the
blood?

• About 45 minutes!
• Your blood passes through the kidneys 300 times a
  day.
• Every day the kidney sends about six cups of
  urine to the bladder.
• The kidney has one million nephrons that filter
  the blood.

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Kidney Stones

• Kidney stones are made of calcium, magnesium, and
  uric acid salts
• Ultrasound waves break the stone into smaller
  fragments that can pass out of the body

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Urinary Tract Infections

• Urine does not normally contain bacteria.
• Bacteria can enter the urinary tract from the
  skin around the rectum and genitals by traveling
  up the urethra into the bladder.
• The bacteria can infect and inflame the bladder
  and cause swelling and pain in the lower abdomen
  and side.
• If the bacteria travel up through the ureters to
  the kidneys, a kidney infection can develop.

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Dialysis

• Uses a machine to filter blood when the kidneys
  do not work