The Excretory System

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The Excretory System

• Getting rid of metabolic wastes!

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Excretory System

• A. Purpose
• Excretion is the elimination (removal) of
  metabolic wastes from the cells.
• B. Why?
• 1.To maintain homeostasis by
• regulating the water content of the blood (blood
  volume)
• maintaining blood pH
• removing waste products from the blood
• 2. How is the human excretory system similar to a
  one celled organisms?
• Analogous to the cell membrane
• Wastes and CO2 diffuse out of cells

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C. How? Using the excretory organs

• SKIN
• Rids body of excess water and salt (SWEAT)
  largest gland
• regulates body temperature through perspiration
• LUNGS
• Rids body of CO2
• LIVER
• Recycling of red blood cells, production of urea
• Urea is made from the breakdown of proteins
  (amino acids)
• KIDNEYS
• Filter (clean) the blood
• Maintain blood pH
• Maintain water content of blood volume

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Regents question

• Which is NOT a role of the kidney?
• Removal of waste products from the blood
• Maintenance of blood pH
• Regulation of water content of the blood
• Maintenance of homeostasis
• Excretion of carbon dioxide

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The Kidneys

• RENAL
• Refers to anything doing with the kidneys
• Kidneys involved w/ these structures
• Ureter
• Tubes that carry urine to bladder from kidneys
• Urinary bladder
• Collects urine for excretion
• Urethra
• Transports urine out of body from bladder

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Kidney Structure

• Renal Artery
• Carries unfiltered (dirty) blood from heart TO
  kidneys
• Renal Vein
• Carries filtered (clean) blood from kidneys TO
  heart
• Renal Cortex
• Outer portion
• Renal Medulla
• Corn shaped inner portion
• Nephrons
• Functional unit of the kidneys!
• Lie between cortex and medulla
• Millions of them!

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Excretory Homeostasis Disorders

• 1. Gout Caused by deposits of uric acid in
  joints. This disease is common with high protein
  diets. Suffer from stiffness and pain in joints.
• 2. Kidney Stones caused by a calcium buildup due
  to improper diet. Painful in the ureter.
•  
• 3. Cirrhosis cause by the consumption of too
  much alcohol. The liver works extra hard and
  produces an excess of fats which scar the liver
  causing liver to shut down.

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Excretory System The Nephron
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Excretory System The Nephron

• Nephrons are the functional units of the kidney
• This is where filtration, pH balance, and blood
  volume are maintained!
• Glomerulus
• Bundle of capillaries
• Bowmans Capsule
• Surround glomerulus
• Loop of Henle
• Maintains water balance
• Collecting Duct
• Collects wastes from filtered blood
• Connected to ureter

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Excretory System Nephron Process

• Nephrons clean and maintain blood in 3 steps
• Filtration (filtering of blood)
• Glomerulus ? PRESSURE ? Bowmans Capsule
• Blood is filtered of water, urea, salts, and
  other materials
• These filtered materials called FILTRATE
• Reabsorption (maintaining blood volume and
  nutrients)
• The good part of filtrate is reabsorbed by
  blood
• Most filtered water re-enters blood to maintain
  volume
• Secretion (maintaining blood pH)
• The bad part of filtrate is secreted back into
  filtrate
• H ions, some water, salts, and urea
• These together are called URINE!
• Urination
• Urine in Loop of Henle ? Collecting Duct ? Ureter
  ? Bladder ? Urethra