The Excretory System
By Kara Weisman
*Organs of the excretory system include
kidneys, liver, bladder, lungs, urethra and
the skin.*
What is the excretory system?
• The excretory system
provides a way for various
wastes to be removed
from the body.
• The Excretory system
balances the chemical
composition of body fluids
by removing wastes and
retaining the proper
amounts of water, salts,
and nutrients.
The Kidneys
• Kidneys are the main organs of the
excretory system.
• They are dark purple in color and are
shaped like kidney beans, hence the
name.
• Kidneys act as the body’s filter.
• There is one kidney on each side of
the spinal column, just above the
waist.
• Our kidney’s filter one liter of blood
per minute, pumped into them from
the largest artery , called the aorta.
• The actual filtering process takes
place within the kidney’s millions of
microscopic nephrons. Nephrons are
made up of tubes and closed in an
even more complex network of
capillaries.
• Kidneys excrete salts, water, and
nitrogen wastes
The Liver
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The liver is considered both part of the
digestive system and the excretory
system.
The liver can regenerate, or grow
back, cells that have been destroyed
by some short-term injury or disease
The liver is the body's largest organ.
It is located in the right part of the
abdomen over the stomach and is
protected by the lower ribs.
The liver of an average sized adult
weighs a little less than four and a half
pounds.
One of the liver’s primary jobs is to
store energy in the form of glycogen,
which is made from a type of sugar
called glucose.
The liver also functions as the body’s
chemical factory. Several important
proteins found in the blood are
produced in the liver.
Proteins & other nitrogenous
compounds are broken down in the
liver by deamination. As a result of
these reactions, a nitrogenous waste
called urea is formed.
The Bladder
• The urinary bladder is the
organ in the excretory system
that stores urine after its
formation by the kidneys
finish the filtering process.
• Urine enters the bladder from
the kidneys through two
ureters and is discharged
through the urethra.
• The bladder releases all of
the urine.
• Average capacity of the adult
bladder is about half a liter.
The Lungs
• The lungs excrete spices of
the excretory system.
• As respiration occurs carbon
dioxide is produced as a
waste product.
• As carbon dioxide builds up
in body cells, it eventually
diffuses out of the cells and
into the bloodstream, which
then circulates to the lungs.
• Water vapor also leaves the
body from exhaling.
The Urethra
• Produces and excretes urine
from the body.
• Urine is a transparent yellow
fluid containing unwanted
wastes, mostly excess water,
salts, and nitrogen wastes.
• the body needs, at a
minimum, to excrete about
0.5 liter (1 pint) of urine
daily to get rid of its waste
products .
• If blood sugar, or glucose is
found in urine, that is a sign
of diabetes.
• The one million microscopic
nephrons that the kidney
filters, performs this critical
blood-filtering function and
produces urine in the
process.
The Skin
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An adult human has between
one and four million sweat
glands.
Most eccrine glands are found
on almost all of the surface of
the body and the outside of the
palms and soles.
Cells at the base of the gland
make sweat, a mixture of water,
salt, and small amounts of
metabolic waste products.
As the sweat moves along ,
much of the salt is reabsorbed,
preventing loss of this
substance.
When sweat reaches the outer
surface of the skin, it
evaporates, helping to cool the
body in hot environments or
during physical excersise.
How do theses structures work together to
accomplish the functions of the system?
As carbon dioxide builds up in body
cells in the lungs, it eventually diffuses
out of the cells and into the
bloodstream, which then circulates to
the kidneys which filters the blood and
other excess wastes, which flows
through the ureter and down into the
urinary bladder which fills up and then
you excrete the urine from your system
through the urethra.
Helpful Websites to find more information:
www.innerbody.com
www.encarta.com
www.google.com/images/excretorysystem
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