Excretion vs. Elimination

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Excretion vs. Elimination
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Excretion vs. Elimination

• Your body makes several kinds of waste, which
  fall into two groups
• Undigested solid wastes
• Wastes made by cells

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Elimination

• Undigested solid waste leaves your body through
  the large intestine
• Water is removed from the wastes in the large
  intestine, which allows for the formation of a
  solid (feces).

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• The solid wastes moves from the large intestine
  to the rectum.
• From the rectum, the solid waste is excreted
  through the anus.

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Excretion

• When waste products made by cells (water, heat,
  carbon dioxide, salts, urea) leave your body
• In many animals, CO2 leaves the body through the
  lungs
• The liquid waste, urine, is made in the kidneys

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• Urine made up of water, heat, harmful chemicals
  (urea), and some salts
• Perspiration when heat, water, and salt are
  excreted by the body through skin (i.e. sweating)

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• Write the correct waste product next to the
  excretory organ
• 1. Skin
• 2. Large intestine
• 3. Lungs
• 4. Kidneys
• (word bank carbon dioxide, solid wastes, salt,
  harmful chemicals, water, heat)

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• The waste products are
• Skin water, heat, salt
• Large Intestine solid waste
• Lungs carbon dioxide
• Kidneys harmful chemicals, heat, salt

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The Excretory System

• The group of organs responsible for removing
  waste products from the body the excretory
  system
• The main organs are
• Lungs
• Kidneys
• Skin

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Lungs

• When we breathe, we excrete CO2 waste, and small
  amounts of heat and water
• Fact your lungs are capable of removing alcohol
  from the blood this is how a breathalyzer is
  able to determine a persons blood alcohol level

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Skin

• Largest organ excretes most of the bodys waste
  heat
• Also removes some water, salts, and very small
  amounts of urea
• Perspiration helps the body cool off
• When sweat evaporates from the skin, it cools the
  body, removing heat

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Kidneys

• Fist sized, bean shaped (i.e. kidney bean) organs
  found on either side of the lower spine
• Main job is to filter out wastes from the blood,
  making them more concentrated in preparation for
  excretion and, in the process of doing this,
  retaining as much water as possible

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• The blood enters the kidney through the renal
  arteries renal veins carry blood back from the
  kidneys to the body
• A ureter connects each kidney to the urinary
  bladder once urine has formed, the ureter
  carries the urine (produced after the blood has
  been filtered for wastes) from the kidney to the
  bladder

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• Another tube, the urethra, carries the urine out
  of the body
• In males, the urethra passes through the penis
  in females, it lies between the pubic bone and
  the front wall of the vagina

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Label the diagram bladder, kidney, renal artery
and vein, ureter, urethra
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Nephrons

• The filtration of the blood takes place in minute
  structures called nephrons, found in the cortex,
  which is the outer layer of the kidney
• The nephrons estimate at more than 1 million per
  kidney

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• In spite of their size, the kidneys filter more
  than 180 L of blood every 24 hours
• Most is reclaimed by the body, only 1.5 L of
  urine is passed each day
• Your blood passes through the kidneys 300 times
  per day

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Label the Kidney cortex, medulla, renal artery,
renal pelvis, renal vein, ureter
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Liver

• A secondary organ of excretion
• Does not excrete wastes, but is important for
  excretion
• Handles cell wastes in several ways
• 1) Breaks down dead red blood cells pass into
  digestive tract, then eliminated with solid waste
  by the bowels

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• 2) Weakens certain harmful substances
• 3) Changes some harmful substances
• Ex the liver makes bile from harmful substances
  bile is important in fat digestion after bile
  works on fat, it is eliminated from the bowels
• 4) Combines certain harmful chemicals
• Ex) liver combines ammonia and some CO2 forms
  urea, which the blood carries to the kidneys
  where it becomes part of the urine