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Excretory System
Excretion: Removing Metabolic Waste
Do Now – Name as many wastes as you can that must leave the
body in order to be healthy
EXCRETORY SYSTEM FUNCTION
To remove waste from the body. It includes the SKIN,
LIVER, KIDNEYS, and LUNGS.
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The SKIN removes
heat from the body
by releasing
SWEAT which
evaporates and cools
our body.
The skin also
removes some of the
same substances as
urine including urea
and salts.
Regents Question
Which human excretory structure aids in
the maintenance of normal body
temperature?
1)Urinary bladder
2)Nephrons
3)Liver
4)Sweat glands
Regents Answer
4)Sweat glands
What is Cellular Waste?
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Cellular waste is one of the products of
cellular metabolism.
These materials are: excess water and salts,
carbon dioxide, and urea.
They must be eliminated from the
organism or they can lead to its death.
Cellular Waste
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When carbon dioxide
builds up in the blood,
the brain signals the
lungs to inhale and
exhale.
Carbon dioxide, a
little water vapor and
heat are removed as
waste products by the
lungs.
The Urinary Tract
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The renal artery brings
oxygen rich, ‘dirty’
blood to the kidneys.
The kidneys remove
toxins, waste and excess
water from the blood.
The urine is sent from
the kidney through the
ureters to the bladder
where it leaves the body
through the urethra.
Regents Question
Which sequence represents the correct
pathway for the removal of urine from
the human body?
1)Kidney-ureter-urinary bladder-urethra
2)Kidney-uretra-urinary bladder-ureter
3)ureter-kidney-urinary bladder-urethra
4)urethra-kidney-urinary bladder-ureter
Regents Answer
1)Kidney-ureter-urinary bladder-urethra
Bowman
Capsule
Glomenul
us Descending
Loop
Ascendin
g Loop
The Kidney
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The kidney is an
excretory organ
composed of many
working units called
nephrons.
Each nephron will filter
the organisms blood
and concentrate the
cellular waste for
removal.
The nephrons filter the
blood and send the
Urine to the ureters to
the bladder where it is
excreted via the
urethra.
How the Nephron Works

Bowman’s Capsule &
Loop of Henle
The capsule will take
out water, amino
acids,
glucose,
salts,
Bowman
Capsule
and urea.
 The Loop of Henle
will reabsorb the
Glomenul
Ascendin
us Descending
g Loop
amino acids, glucose
Loop
and, salt. (makes
urine concentrated)
http://video.about.com/surgery/Kidney-Transplant.htm
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Regents Question
In humans, which substance is normally
excreted through both alveoli and
nephrons?
1)Water
2)Ammonia
3)Glucose
4)Uric acid
Regents Answer
1)Water
The Liver
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The liver makes bile to
emulsify fats.
The liver filters the blood
to remove the dead red
blood cells
The liver makes digestive
enzymes.
The liver makes some
amino acids
The liver removes toxic
ammonia by turning it
into urea and excreted as
part of the urine.
Elimination from the Body
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The concentrated urine will be dumped into
the collecting tubules of the kidney.
Each kidney will pass the urine to a large
muscular organ called the urinary bladder
via tubes called ureters.
The Bladder will eliminate the urine from
the body via a tube called the urethra.
The Large Intestine
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Undigested food in a
solid form passes to
the large intestine
Water is reabsorbed
into the body from
the undigested
material
Solid waste is stored
until it is excreted
from the body.
Summary of the Excretory System Video Clip