Plants and the lower members of the animal kingdom can obtain their O2 and eliminate
their CO2 by diffusion.
Higheranimals, including humans, require a breathing apparatus in order to exchange
these gases.
Artificial Respiration’ (also known as ‘TheKissofLife’) you can help save someone’s life by helping them to breathe, but you can’t do their
respiration for them.
Also in a dusty or dangerous atmosphere/ underwater you might use a respirator to help you to breathe more easily, but it
doesn’t do your respiration for you.
Breathing happens in your lungs, and your diaphragm help with this. Your lungs are part of the respiratory system.
Respiration happens in every cell in your body (and in fact every living cell in plants and animals).
In unicellularorganisms, gases exchange with the
surrounding medium by
diffusion across the moist
cell membrane of the cell.
The membrane must be moist. It is more difficult
for gases to diffuse across a
dry membrane.
Gases enter and exit the air spaces of leaves
via the stomates. The
openings of stomates
are controlled by guard
cells.
Older stems are usually impermeable to gases. Some
trees have lenticels that let air
into the cambium.
In many largetrees, there are enough cracks in the bark so
that air is available for the
cambium and living phloem
cells.
Roots can exchange gases with the soil.
This is done via the
moistcell
membranes of the
cells in the lower
parts of the roots.
Hydra does not have any specialized breathing apparatus. It only has twocelllayers and therefore does not need one.
Gills are used by marine worms,
molluscs (clams),
and fishes. The gill
lamellae (layers)
have a large area
for exchange of
gases.
The afferent vessel carries blood toward the gill. This blood is high in CO2
and low in O2.
The blood in the gill exchanges gases with the water.
The CO2
leaves the gill and enters the water while
the O2 leaves the water and enters the gill
Then, the efferent vessel carries blood away from
the gill. This
blood is high in O2
and low in CO2
Each cell in the body of an insect or spider is in contact or near a breathing tube known as a trachiole.
A group of trachioles will be combined to form a larger
breathing tube called a trachea.
Grasshoppers have numerous tracheas that exit through holes on the side of the body called spiracles.
These spiracles are used for gas exchange, the "spir" part is
also found in the word "respiration.
Frog and other amphibians, about half of the gas exchange
takes place across the skin.
The other half of the respiration is
done using lungs.
Frogs do not have a diaphragm so they must force air into the lungs.
This is called positivepressure
breathing.
Humans have a diaphragm so their
breathing is by negative pressure.
Birds have a complicated respiratory system consisting of lungs and airsacs in the bones. Air is cycled
through the air sacs in the hollow
spaces in the bones.
The human respiratory system consists of the lungs, bronchi and
trachea.
The lungs are located in the
thoracic (chest) cavity, the area in
the chest above the diaphragm. The
heart is also located in the chest
cavity.
In humans, the diaphragm
contracts and makes the
chest cavity larger.
The air that enters the
lungs from the outside is
high in O2
and low in CO2.
Inspiration is the term used for inhaling air. When the diaphragm relaxes, the pressure in the chest
increases and forces the air out. Expiration is term used for exhaling air The
air that leaves the lungs is low in O2
and high in CO2.
Control of breathing is done by the nervous system. When CO2
increases as a result of exercise, for
example, the breathing rate and
heart rate increase.
When there is little CO2
in the
blood, the nervous system slows
the breathing rate.
Gases are exchanged in the alveoli of the lungs. Air makes its way down to the air sacs where O2 passes through the capillary walls by
diffusion, and into the blood stream where it enters the red blood cells.
Blood leaving the alveoli is high in O2 and low in CO2.
Simultaneously, CO2
and
some water leave the blood
stream and enter the alveoli
of the lungs.
Diffusion process
How diffusion works
It work through higher concentration to a lower concentration