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