Do Now - Give as many
examples of EXCRETION
as you can.
And it’s not this
The metabolic activities of living cells
produce waste materials.
EXCRETION – is the life process by which the wastes of
metabolism are removed from the body.
The metabolic wastes that are removed are
Waste can be converted into AMMONIA
Ammonia is a toxic substance.
Ammonia must be washed out of and away from
organisms immediately so they aren’t poisoned.
Organisms that live in a watery
environment can excrete ammonia directly
into the environment by diffusion.
Fresh water Paramecium's can excrete a large amount
of water using their CONTRACTILE VACUOLES.
In humans and other mammals, ammonia is
converted into UREA by the liver.
It is moderately toxic.
Urea is soluble in water, and can be
eliminated in urine and sweat.
Some organisms convert ammonia to URIC ACID.
It takes a lot of energy to produce uric acid,
but there’s a big payoff.
URIC ACID can be excreted as a dry waste.
This helps organisms like birds conserve water.
Looking like bird poop can be good!
Other waste products of plant metabolism
can be stored in the plant cell VACUOLES.
All the cells of the hydra are in contact with the water.
Excretion takes place by diffusion
through the cell membranes.
Freshwater hydras excrete CO2
and the nitrogenous waste product ammonia.
In the earthworm, carbon dioxide is excreted
by diffusion through the thin, moist skin.
Water, mineral salts, and urea are excreted by pairs of
excretory organs called NEPHRIDIA.
Wastes are filtered out of the body fluid by the nephridia
and excreted through pores into the environment.
NEPHRIDIA are found in most of an
earthworm’s body segments.
In the GRASSHOPPER, carbon dioxide from the
body cells diffuses into the tracheal tubes.
It leaves the body through the SPIRACLES.
Water, salts, and uric acid crystals accumulate in the
MALPIGHIAN TUBULES, which are the excretory organs.
From the
the wastes pass into the
digestive tube,
where most of the water
is reabsorbed.
The metabolic wastes of humans include
carbon dioxide, water, salts, and urea.
Excretory wastes pass from the cells into the blood,
and are carried to the excretory organs
that expel them from the body.
Brain Pop
The human excretory organs
include the
In humans, carbon dioxide and water vapor are
excreted by the LUNGS when we exhale.
This is what happens to your lungs when you smoke.
The LIVER is a large organ that performs
many functions essential to human survival.
The liver is also responsible for the breakdown
of red blood cells.
This is what happens to your liver when you abuse alcohol.
Water, salts, and UREA are excreted by the
Human KIDNEYS remove urea from the blood
and regulate water and salts in the blood.
As water is reabsorbed
by the kidney,
URINE is formed.
The urine passes through
the URETERS to the
where it is stored.
Urine is eliminated from
the body through the
People who suffer
kidney failure
undergo DIALYSIS
which filters the
blood through a
machine to remove
the wastes.
Can you drink your own urine to stay alive?
click here
Medicine from URINE??
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excrete wastes
including water, salts,
and a small amount of urea.
The mixture of wastes and
water excreted by the sweat
glands is called sweat, or
PERSPIRATION functions primarily in the
regulation of body temperature.
As sweat evaporates from
the skin, heat is absorbed
from skin cells.
The absorption of heat
lowers body temperature.
Temperature regulation is an example of homeostasis.
The normal human body temperature is 98.6◦F.
When your body temperature is out of balance,
it is a sign of illness.