1. The Excretory System
Aaron Wong

2. What does it do? Every cell produces metabolic wastes such as: Salt
Carbon dioxide
Urea (toxic compound produced when making energy)
The excretory system’s job is to remove these useless and harmful wastes from the body.

3. The Organs The main organs of the excretory system are:
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

4. Kidneys Structure
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.
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

5. Blood Purification
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

6. Blood Purification Reabsorption
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..

7. Urinary system Urine is the material that remains after reabsorption
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
Urine is released through the urethra
tube

8. 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?
Liquid that you consume goes
into the blood
This increased concentration should
force water into cells, swelling your body
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

9. Skin and Lungs Skin excretes waste products from
the body through perspiration
This includes water, salt, and a small
amount of urea and other toxic substances
The lungs excrete carbon
dioxide during respiration
CO2 is produced when
energy is taken from food
Simple breathing animation >>>>>>>
Blue: oxygen, purple: CO2

10. When something goes wrong…
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.
Dialysis Animation
:: Medical science is working
on developing an artificial
kidney transplant for the future!

11. A Healthy Excretory System
As with all of your body systems eating well promotes a healthy excretory system, especially getting enough dietary fiber
Diabetic kidney disease can be prevented by keeping blood sugar in your target range
For more information visit:
(kidney disease)
(detailed explanation of reabsorption)
(overview)

12. Bibliography
(slide 6, “Secretion”)
(slide 9)
(slide 10, “Skin”)
(slide 11)