The Human Body: The Excretory System

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The Human BodyThe Excretory System

• Textbook Chapter 34
• Review Topic 1

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Function

• Removes toxins and wastes which build up in the
  body as a result of metabolism
• Regulates the amount of fluid and salts in the
  body and maintains pH of the blood
• Helps regulate homeostasis

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Parts

• Lungs
• Excretes carbon dioxide
• Skin
• Excretes water and salts contained in sweat
• Kidneys
• Major excretory organ in the body

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Kidneys

• Bean-shaped
• Filters out wastes, water and salts from the
  blood
• Two regions
• Renal cortex outer region
• Renal medulla inner region

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• Contains microscopic tubules and blood vessels
• Renal pelvis center of kidney where these
  filters are found

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• Nephron filtration
• Each kidney has 1 million filtering units called
  nephrons
• Blood enters each Nephron through a long tube
  surrounded by capillaries called a glomerulus
• Surrounded by the Bowmans capsule

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• Renal artery transports nutrients and wastes to
  the kidney
• Branches into smaller blood vessels forming the
  glomerulus
• Blood vessel walls are thin and under high
  pressure

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• Urea nitrogenous waste product containing water
  and substances dissolved in water
• Pushed through capillary walls into the Bowmans
  capsule
• Red blood cells and proteins are too large and
  remain in the blood stream

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• Reabsorption/formation of urine
• Filtrate collects in the Bowmans capsule and
  flows through renal tubules (loop of Henle and
  collecting tubule)
• Most water and useful substances (ex. glucose,
  minerals) are reabsorbed back into blood stream
  (reabsorption)

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• Excess fluids and toxic substances are collected
  to form urine
• Leaves the kidneys through ducts called ureters
• Urine is stored in the urinary bladder
• Exits the body through the urethra

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• Each kidney filters 180 L of blood a day in
  adults to produce 1.5 L of urine
• Process requires large amounts of energy
• Use 20-25 of your bodys oxygen intake for their
  internal energy requirements!
• Controls pH balance by absorbing or filtering out
  acids or bases to regulate pH of the blood

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• Urinary System BrainPop

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Kidney Disorders

• Infections
• Start as bladder infections which spread to
  kidney
• Fever, chills, mid-/lower-back pain
• Can be caused by blockages
• If untreated, kidneys can scar causing a loss in
  function
• Can be treated with antibiotics

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• Nephritis
• Inflammation (painful swelling) of the glomeruli
• Cause by blockages
• Blood in urine, swelling of body tissues, protein
  in urine
• Can improve on its own but may require a special
  diet or prescription drugs to treat the infection

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• Kidney Stones
• Crystallized solid (calcium compound) which forms
  in the kidney
• Small stones can be passed out in urine
• Larger stones are broken up using ultrasonic
  sound waves or removed using surgery

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• Diabetes/High Blood Pressure
• Causes reduced kidney function or kidney failure
• Illegal/Prescription Drugs
• Can cause kidney damage

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Treatments

• Dialysis
• An artificial
• kidney machine
• filters out wastes
• and toxins from
• a patients blood

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• Two types
• Blood is passed through the machine temporarily
  to be filtered and cleaned, then returned (3-4
  hours/3 days week)
• Membrane lining the abdomen acts as an artificial
  kidney by injecting it with a special fluid
  through a small tube attached to the patients
  body to collect draining wastes (30-40 min/daily)

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