A closer look at the excretory system for Year 8 Science students at Saint Ignatius College Geelong.

1. FUNCTIONING ORGANISMS.
05. Excretory system.
Ian Anderson
Saint Ignatius College Geelong

2. EXCRETORY SYSTEM.
 Responsible for
 Processing and elimination of
metabolic wastes.
 CO2 is excreted through your lungs.
 Urea & salts are excreted by your
kidneys and removed from your
body as urine.
 Controls amount of water in our
body.
Source: http://www.cakechooser.com/

3. EXCRETORY SYSTEM.
 As our cells undergo their many metabolic
processes, harmful wastes are continually being
produced.
 Metabolic wastes include CO2, urea, salts, water, etc.
 These wastes must be collected and removed
before they increase in concentration to poisonous
levels.
 The process of removing these metabolic wastes is
called excretion.

4. EXCRETORY SYSTEM.
 Faeces is waste from your digestive system,
however it is not metabolic waste and therefore its
removal is not excretion.
 Faeces is undigested food that your body has not been
able to process.
 Removing digestive wastes is
called egestion.
Source:
http://flickrhivemind.net/Tags/diarrhea/Timeline

5. EXCRETORY SYSTEM.
The organs of excretion are the:
 Lungs.
 Skin.
 Liver.
 Kidneys.

6. EXCRETORY SYSTEM.
The lungs.
 Releases CO2 into the air from
the bloodstream.
 CO2 is a waste product of
cellular respiration that occurs
in all our cells.
 Our blood collects CO2 from
our cells and transports it to
our lungs where it diffuses into
the alveoli and is then breathed
out. Source:
http://www.uic.edu/classes/bios/bios100/lecturesf04am/lect20.htm

7. EXCRETORY SYSTEM.
The skin.
 Sweat is a mixture of three
metabolic wastes.
 Water, salts & urea.
 Sweat has a cooling effect on
your body (evaporative
cooling).
Source:
http://www.youtube.com/watch?v=RJItaB8M24c

8. EXCRETORY SYSTEM.
The liver.
 Has several functions (not all
are involved with excretion).
 Breaks down protein waste
products into urea.
 Detoxifies blood (e.g. alcohol).
 Breaks down old red blood cells.
 Stores glucose as glycogen.
 Produces bile.
Source: http://11uexcretorysystem.wordpress.com/

9. EXCRETORY SYSTEM.
The kidneys.
 The primary organ of the
urinary system.
 Urinary system is made up of:
 Kidneys.
 Ureters.
 Bladder.
 Urethra.
Source: Sharwood (2005)

10. EXCRETORY SYSTEM.
The kidneys.
 Made of ~2.4 million
tiny structures
called nephrons.
 Each nephron is a
filtering machine.
Source: http://www.beltina.org/health-dictionary/nephron-
function-kidney-definition.html

11. EXCRETORY SYSTEM.
The nephron.
 Blood is pumped into
kidneys and forced
under pressure via specialised
capillaries
called a glomerulus
into the Bowman’s
capsule.
Source: http://www.beltina.org/health-dictionary/nephron-
function-kidney-definition.html

12. EXCRETORY SYSTEM.
The nephron.
 The filtrate then travels
through the
proximal tubules
and Loop of Henlé
where wanted
substances such as
glucose, vitamins,
minerals and water
are reabsorbed into the
bloodstream.
 The filtered waste (now
called urine) then leaves
the kidney and moves
into ureter.
Source: http://www.beltina.org/health-dictionary/nephron-
function-kidney-definition.html

13. EXCRETORY SYSTEM.
The kidneys.
 Once urine leaves the kidney it
enters the ureter and travels to
the bladder, where it is stored.
 Urine then travels through the
urethra out of the body when
your urinate.
Source: Sharwood (2005)

14. BIBLIOGRAPHY.
Sharwood, J. (Ed.). (2005). Science Edge 2.
Melbourne: Thomson Learning.

15. http://sickscience8.wikispaces.com/