Download The Excretory System

The Excretory System
Aaron Wong
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What does it do?
Every cell produces metabolic wastes such as:
 Salt
 Carbon dioxide
 Urea (toxic compound produced when making
energy)
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The excretory system’s job is to remove these usele
and harmful wastes from the body.
The Organs
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The main organs of the excretory system are:
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Kidneys
SKIN
Lungs
skin covers and protects your body
lungs located in chest and protected by ribcage
kidneys found on either side of backbone and about the size of a
fist
Kidneys Structure
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Made of Inner (renal medulla) and
outer (renal cortex)
The functional units of the kidney are
nephrons
Each nephron has its own blood
supply through the use of 4 parts.
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Ateriole :: Where the blood enters
Capillaries :: Filtration
Collecting duct :: Waste from blood
ends up here which leads to
ureter
Venule :: Where the purified blood
exits
Blood Purification
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It is broken into three processes: filtration, reabsorption, and secretion.
Filtration
:: Blood enters nephron and flows into the
glomerulus, a small network of capillaries is
held in the upper end of the nephron by Bowman’s
capsules
:: Because the blood is under pressure and the
capillaries are permeable fluid flows into Bowman’s
capsule
:: The filtrate (filtered materials) contains water, urea, glucose, salts, amino
acids, and some vitamins
Blood Purification
Filtration, reabsorption, and secretion
animation
Reabsorption
:: Most material removed from the blood
goes back into the blood through
reabsorption
:: The nutrients are taken out of the filtrate
with active transport and then put back
in the blood
Secretion
:: The cells of the tubules remove certain molecules and ions from the blood
and deposite these into the fluid within the tubules.
: Tubular secretion of H+- is important in maintaining control of the pH of the
blood..
Urinary system
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Urine is the material that remains after reabsorption
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It is concentrated in the loop of Henle where water is conserved and
the volume of urine minimized
Urine is collected in the urinary bladder
while purified blood goes back into normal
circulation
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Urine is released through the urethra
tube
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The Kidneys and Homeostasis
:: The kidneys regulate water content in the blood, which controls blood volume, pH, and
waste in the blood.
:: How do they do it?
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Liquid that you consume goes
into the blood
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This increased concentration should
force water into cells, swelling your body
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However the kidneys control this by
lowering the rate of reabsorption of water
As for salt, the more you eat,
the less that is returned to the blood
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Skin and Lungs
Skin excretes waste products from
the body through perspiration
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This includes water, salt, and a small
amount of urea and other toxic substances
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The lungs excrete carbon
dioxide during respiration
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CO2 is produced when
energy is taken from food
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Simple breathing animation >>>>>>>
Blue: oxygen, purple: CO2
When something goes wrong…
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The major disease to the excretory system is kidney disease
This can lead to kidney failure, and the inability to remove waste
products
Many kidney problems can be treated by dialysis, where a machine acts as
a kidney. However, it is very expensive and time consuming. Kidney
transplants are an alternative to dialysis.
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Dialysis Animation
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:: Medical science is working
on developing an artificial
kidney transplant for the future!
A Healthy Excretory System
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As with all of your body systems eating well promotes a healthy excretory system,
especially getting enough dietary fiber
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Diabetic kidney disease can be prevented by keeping blood sugar in your target
range
For more information visit:
http://www.emedicinehealth.com/chronic_kidney_disease/article_em.htm (kidney
disease)
http://health.howstuffworks.com/kidney3.htm (detailed explanation of reabsorption)
http://www.quazen.com/Science/Biology/Human-Body-the-Excretory-System-.18801
(overview)
Bibliography
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http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/K/Kidney.html (slide 6, “Secretion”)
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http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookEXCRET.html (slide 9)
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http://www.skin-care-information.org/how-the-skin-works.html (slide 10, “Skin”)
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http://www.diabetes.org/type-1-diabetes/kidney-disease.jsp (slide 11)