3.4 Excretory System
What does it do?The body produces a number of different
types of wastes
If not removed these can cause serious harm
The job of this system is the removal of these wastes…called EXCRETION
How does it work?In order for it to do its job properly this
system must use organs from other body systems
Such as;IntestinesRectumLungsAny others????
Waste ProductsCarbon dioxide – from oxygen being
released by the blood cells
Ammonia – a VERY toxic compound caused from protein breakdown by cells
Urine – a result of chemical processes that create salt and water as waste products
The Main Organs InvolvedThe Liver The Kidneys
The LiverIs involved in the digestive system as well
Its primary job is to take the toxic ammonia produced by the cells and change it to something less harmful
It turns ammonia into UREA
The LiverUrea is far less toxic than ammonia, but it
still needs to be disposed of
The liver releases the urea into the blood stream to head towards its next filter point
The KidneysIs the main organ in the excretory system
It produces the urine for the body
**They are the filters of the blood, they strain out all the unwanted;SaltsWater Urea
KidneysFilters every drop of your blood about 300X a
day; that’s once every 4 minutes
During this filtering, urine is created by water, salt and urea being pulled out
Kidneys keep the water levels in your body balanced, the more water you drink the more you urine you create.
Ureters, Bladder and UrethraUreters – Long tubes that connect the
kidneys to the bladder
Urethra – Tube where the urine exits the body
Bladder – Is a sac covered in muscle tissue that expands when urine enters it.Can store about 1L or urine – When full
muscles contract and push out urine through the urethra
Your SkinHave you ever tasted Sweat?
What does it taste like?
Sugary? Sweet? Sour? Bitter? NO, its salty
Your SkinYour skin has thousands of tiny sweat glands
just below the surface
These glands assist your body by helping to keep your body cool (sweating)
They also help by removing any excess salt
How does Urine Form?1. Blood enters the kidneys through the
renal artery
2. This artery splits into smaller and smaller vessels
3. These small capillaries enter filtering units called nephrons
The kidney has millions of nephrons
How does Urine Form?4. These microscopic units remove the wastes
from blood and produce urine
5. The “clean” blood returns to the body through the renal vein
6. Urine flows through a separate vessel and into the ureter
Urine in DetectionSeveral diseases have been detected by
testing patients urine samplesDiabetes – detection of glucose (sugar) in the
urine because the kidneys have problems filtering it
Sports athletes undergo urine tests before and after competition to check for any illegal/banned substances in their system.
Olympics
DialysisPeople with kidney or liver problems can lead
normal healthy lives due to dialysis
It is a machine that will remove the wastes of the body that the kidneys normal would remove
The patients blood flows out of the person through a special Selectively Permeable Membrane and them back into the person – takes 4-6 hours, 3x a week
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