The document discusses the human excretory system and its function. It defines excretion as the process of removing metabolic waste from cells. The primary function of the excretory system is to eliminate useless by-products, eradicate harmful chemical buildups, and maintain steady chemical concentrations. The main human excretory organs are the kidneys, skin, lungs, and liver, each of which removes different waste substances from the body.

2. waste
activities
eat
drink
breath
waste waste
It’s not about eat or drink …..
It’s about discharging process

3. production and
release of a
useful substance
(enzyme &
hormone) by a
gland or cell
the discharging
process of
waste matter of
metabolism
product
the act of
eliminating solid
or semisolid
waste materials
(feces) from the
digestive tract
Discharging process
defecation
excretion
secretion

4. Liver
Lung
Kidney
Excretion
Skin
You’ll learn…

5. § Excretion is the discharging process of
removing metabolic wastes.
§ The primary function of the excretory
system is:
ü Eliminates useless by-products excreted
from cells
ü Eradicates harmful chemical build-ups
ü Maintains a steady, balanced chemical
concentration
§ Human excretory organs:
The Kidneys The Skin
The Lungs The Liver

6. Excretory organ Function Substance
produced
The urinary system is
responsible for maintaining a
stable internal environment
for the body
Urine
Breathing and cellular
respiration that provides
energy for cellular activities.
Carbon
Dioxide (CO2)
and Water
(H2O) vapor
Protecting body from physical
destruction, controlling body
temperature, receiving stimuli
water, salts, &
urea
Broken down some proteins &
other nitrogenous compounds
a nitrogenous
waste called
Urea