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GASEOUS EXCHANGE
1
...
In
addition to respiration, photoautotrophs like plants do carry out gaseous
exchange for the process of photosynthesis
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1
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During the process of photosynthesis, carbon dioxide is taken in while oxygen
is given out whereas in respiration, oxygen is taken in and carbon dioxide is
given out
...
During this
process, carbon dioxide gas is taken in while oxygen gas released as by-product
is given out
...
It is
the process in which food is oxidized to release energy
...
The process of
exchange of gases in plants takes place mainly through minute openings called
stomata present in leaves
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S
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Respiration
Catabolic process
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Breaking down of food into
inorganic substances
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Occurs in plants
...

Releases oxygen gas
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Chlorophyll is required
...

Occurs in all living organisms
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Releases carbon dioxide gas
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Chlorophyll not required
...
Through
these openings, plants exchange gases with their environment
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They are

GASEOUS EXCHANGE
chlorophyll containing cells with thicker inner while thinner and elastic outer
cell walls
...
During daytime, as a result of ongoing process of photosynthesis,
the accumulation of photosynthetic solutes causes increase in turgidity of the
guard cells
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1
...
In order to obtain energy from food, they take in oxygen
and give out carbon dioxide
...

The respiratory medium for aquatic animals is water whereas for terrestrial
animals is air
...
In order to exchange gases, animals have a
respiratory surface
...
In multicellular animals, their
body surface or some internal surface could serve as the respiratory surface
Properties of Respiratory surface:
1) Thin, 2) Wet, 3) Permeable, 4) large in relation to the volume of the body
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For example, the total surface area of the respiratory surface in human is
about 20 times to the size of the body
...
It is also necessary to compensate
for the small surface area to volume ration of the animal body

1
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Like other terrestrial vertebrates, our respiratory surface is
located inside the body in the form of alveoli contained in paired organs, lungs
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4
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LUNGS:
Each lung is soft, spongy and pinkish in appearance
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The space between pleural membranes is filled with Fluid
that acts like a lubricant
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Lungs
are enclosed in a bony cage made up of a flat sternum in front, 12 pairs of ribs
from front to back where vertebral column is present
...
In the lower part of thorax, lies a sheet of muscles called
Diaphragm which separates it from abdominal cavity
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Each alveolus is the respiratory surface
...
It is enclosed by a dense capillary network
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The Air
passage ways consists of Nostrils, Trachea, Bronchi and Bronchioles
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This entire
passage through which air passes is lined by mucous secreting ciliated cells
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The hairs in nasal sacs as well as ciliated epithelial lining and

GASEOUS EXCHANGE
mucous keep the air clean by trapping and removing dust and germs
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Trachea:
The internal opening of nasal sacs opens into a long tube, Trachea
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The opening of larynx is known as glottis which has a lid like
cover,
epiglottis
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Trachea has C-shaped cartilaginous rings which prevent it from collapsing
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Each bronchus do have C-shaped cartilaginous rings
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As soon as it enters into the lung, it
breaks up into many smaller ducts or Bronchioles
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1
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2 Process of Breathing:
Since the respiratory surfaces are located deep inside the body in the lungs
...
It is achieved through the process of breathing or
Ventilation
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, Inspiration
and expiration
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Surprisingly, we use normally about ½ liter of the air coming
into the lungs
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It involves contraction of
intercostals muscles and diaphragm
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So the external air
rushes inside from high pressure to low pressure
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Expiration:
It is just reverse of inspiration
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Both, intercostals muscles and diaphragm are relaxed
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Both the activities depress the chest
inside
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This forces the air present in lungs to outside
through the body
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5 GASEOUS EXCHANGE IN ALVEOLI:
The gaseous exchange takes place at the level of alveoli
...
This
gaseous exchange involves diffusion which becomes possible at this level
because both alveolus and blood capillaries, are only one cell layered in
thickness
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5
...
03

About 4

Exspired air (%)

About 79
About 79
Saturated
Variable
Atmospheric Temperature 37 degree celcius

Carbon dioxide if passed through limewater turns it milky
...
In (B) if atmospheric air is passed
through the lime-water, the later remains unchanged
...
5
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It is regulated by hypothalamus of
our brain
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For instance, if a person is doing
exercise, its rate of breathing would increase because of increased
consumption of oxygen by his muscles
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If the exercise condition persists, the muscle cells will start
breaking down Glucose without oxygen
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As a result of this, lactic acid is formed in the muscles rather
than carbon dioxide
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The
breaking down of lactic acid requires additional amount of oxygen which is
termed as “oxygen debt”
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Artificial Ventilator:
A machine that works like lungs when patient's natural breathing becomes
difficult
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GASEOUS EXCHANGE
1
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It is caused
either by smoking or by some bacteria
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Emphysema:
It is related to the progressive destruction to the alveoli due to long
term exposure usually to the industrial pollutants
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It causes cough with phlegm production
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In pneumonia, the alveoli are infected so they may be filled with fluid or pus
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The patient suffers from fever, cough, chill and
chest pain
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It is characterized by
shortness of breath, chest pain, fever, wheezing sound during expiration and
cough
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It may obstruct the air-ways making
it difficult to breath for its patient
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Due to smoke or air pollution,
abnormal cells appear in lungs which may spread to other tissues
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