Biology 7.2
Transcript of Biology 7.2
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GRYFFINDORS
BISCUIT
PRESENTATION
CHAPTER 7 :RESPIRATION
7.2 : The Respiratory Structures and BreathingMechanisms in Humans and Animals
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RESPIRATORY STRUCTURES
Breathing is the exchange of gases between an organism and the environmentand it takes place through specializedstructure called the respiratory structure.
The respiratory structures in humans and animals are shown in table below.
The respiratory structures of most organisms have the following three basic
characteristics :a.) Moist respiratory structures to facilitate the diffusion of oxygen and carbon
dioxide.
b.) Thin respiratory wall that is one cell thick to allow gaseous exchange to take
place at faster rate.
c.) A high total surface area to volume ratio helps to increase gaseous exchange.
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THE RESPIRATORY STRUCTURES AND
BREATHING MECHANISMS IN
ORGANISMS
PROTOZOA :
The respiratory surface of a unicellular organism is its entire
plasma membrane.
The unicellur organisms have high total surface area per
volume ratio.
Hence,simple diffusion alone is sufficient to transport gases
into,around and out of their bodies.
Their aquatic habitats ensure that the plasma membrane is
constantly moist so that respiratory gases can easily dissolve and diffuseacross the respiratory surface.
The thin plasma membrane allows the rapid diffusion of gases.
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THE RESPIRATORY STRUCTURES AND
BREATHING MECHANISMS IN
ORGANISMS
INSECTS :
The respiratory system insects is known
as tracheal system.
The tracheal system consists of a
network of air tubes called trachea.
Air enters the trachea through tiny
openings called spiracles.
The trachea are lined with rings of chitin
which prevent them from collapsing. The trachea branch into fined tubes called tracheoles.
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THE STRUCTURAL ADAPTION OF TRACHIOLES FOR GASEOUS
EXCHANGE.
The tracheoles branch throughout the body of an insect and penetiate into
the body tissue.
>> This means that oxygen can be channeled
directly through the cells
The large number of tracheoles.
>> Provides a large surface area for the
diffusion of respiratory gases.
The tips of the tracheoles have thin permeable
walls and contain water in which the respiratory
gases can be dissolve and diffuse rapidly into the body cells.
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THE BREATHING MECHANISM OF INSECTS.
Insects inhale and exhale through the
rhythimic relaxation and contraction of
their abdominal muscles.
When an insect inhale,the abdominal relax
and the spiracles open.
Air pressure inside the trachea decreases
and air is drawn in.
When the insect exhales,the abdominal muscles contract.
The increase air pressure forces air out through the spiracles.
The tracheal system with its network of small tubes allows oxygen to be
absorb directly from rhe atmosphere into the body cells.
There is no blood circulatory system in insects.
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THE RESPIRATORY STRUCTURES AND
BREATHING MECHANISMS N
ORGANISMS
FISH :
Gills are speacialised respiratory structures fo gaseous exchange in water.
Each gill has two rows of thin filament arranged in v-shape.
These filaments consist of numerous thin-walled lamellae.
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THE STRUCTURAL ADAPTION OF GASEOUS EXCHANGE.
There are large number of filaments and lamellae.
>> To provide a large surface area for efficient gaseous exchange in fish.
The membrane of gill is thin.
>> To allow the rapid absorption of respiratory gases into the blood
capillaries.
The filaments are supplied with network of blood capillaries.
>> For an efficient absorption and transport of respiratory gases.
The gill filaments are constantly surrounded by water.>> To enable respiratory gases to dissolve in them.
The efficiency of the gaseous exchange is further enhanced by water.
>> To maximize the oxygen transfer because as water flows over the gills in
one
direction,the deoxygenated blood flows in the opposite direction throughthe
blood capillaries in the lamellae.
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THE BREATHING MECHANISM OF FISH.
When the mouth opens,the floor of the buccal cavity lowers.
At the same time,the opercular cavity enlarges and the operculum closed.
Hence,water with dissolved oxygen is drawn into mouth.
When the mouth closes,the floor of the buccal cavity rises.
Water flows through the lamellae and gaseous exchange between theblood capillaries and water takes place.
At the same time,the opercular cavity becomes smaller. The pressure in thebuccal cavity is higher than the pressure outside.
The higer water pressure forces the opperculum to apen and water to flowout through the opperculum.
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THE RESPIRATORY STRUSTURES AND
BREATHING MECHANISMS IN
ORGANISMS
AMPHIBIANS :
The gaseous exchange occurs in the skin and in
the lungs.
THE STRUCTURAL ADAPTIONS OF THE SKIN FOR
GASEOUS EXCHANGE.
The skin is thin,moist and permeable.
>> To enable a rapid and efficient exchange
of gases between the skin and the air.
Beneath the skin is a network of blood
capillaries.
>> To absorp and transport respiratory gases to and from all the body cells.
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THE STRUCTURAL ADAPTION OF LUNGS FOR GASEOUS EXCHANGE.
The lungs of a frog consist of a pair of thin-walled
sacs for rapid diffusion of respiratory gases.
There are numerous inner partitions in the lungs.
>> To increase surface area to facilitate gaseous
exchange.
The membranes of the lungs are thin.
>> For rapid diffusion of gases
The membranes of the lungs are moist.
>> To allow respiratory gases to dissolve and diffuse into the blood
capillaries.
The lungs are supplied with a rich network of blood capilllaries.
>> To transport the respiratory gases to the body cells.
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THE BREATHING MECHANISM OF FROGS.
The bucco-pharyngeal floor lowers and the glottis closes.
As a result,fresh air is drawn into the bucco-pharyngeal cavity.
When the glottis open,the nostrills close and the bucco-pharyngeal floor
rises. The higher air pressure forces air into the lungs.
The lungs expand when air pushed in.
When the lung muscles contract,air is expelled from the lungs.
The air escapes from the nostrill.
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THE RESPIRATORY STRUCTURES AND
BREATHING MECHANISMS IN HUMANS
LUNGS :
Located in the thoracic cavity.
Protected by ribcage.
INTERCOSTAL MUSCLE :
Found between the ribcage.EPIGLOTTIS :
A flap that closes the air passage mometarily
during swallowing to prevent food and water
from entering the trachea.
TRACHEA : Supported by C-shaped cartilage rings which keep the trachea open.
The trachea will collapsed during inhalation without the cartilage due to theatmospheric pressure outside is higher than the pressure inside the trachea.
Ephitelial cells are lned with the cilia to sweep the dust together with the foreignparticles towards the back of the mouth to be swallowed or coughed out.
Goblet cells will secrete mucus to trap dust and microorganisms present in theair.
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BRONCHI :
The two tubes divided from the lower end of
trachea.
BRONCHIOLES :
Each bronchus subdivides repeatedly to form
smaller tubes called the bronchioles which end
in small air sacs called the alveoli.
ALVEOLI :
Alveoli are thin-walled air sacs where gaseous exchange occurs.
DIAPHRAGM :
A dome-shaped sheet of muscle.
Play important roles in the breathing mechanism in human.
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ADAPTATION OF ALVEOLI FOR GASEOUS EXCHANGE.
There are large number of alveoli.
>> To provide a large surface area for efficient
gaseous exchange.
The inner surface of each alveolus is moist.>> To enable oxygen and carbon dioxide to dissolve
in it and diffusion to take place.
The outer surface of each alveolus is covered by a
network of blood capillaries.
>> To provide a large surface area to volume ratio for the rapid diffusion
and
transport of respiratory gases.
The wall of an alveolus in only one-cell thick.
>> To allow the diffusion of respiratory gases across the membranes totake place
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THE HUMAN BREATHING MECHANISM.
INHALATION :
The external intercostal muscles contract while the
internal intercostal muscles relax.
This will cause the ribcage to move upwards and
outwards.
At the same time,diaphragm muscles contract and
become flatten.
These two actions cause the volume of thoracic cavity
to increase and the pressure of the thoracic cavity to
decrease.
Higher atmospheric pressure on the outside forces the
air into the lungs.
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EXHALATION :
The external intercostal muscles relax while the intercostal
muscles contract.
This action causes the ribcage to move downwards and
inwards.
At the same time,the diaphragm muscles relax and curve
inwards.
These two actions cause the volume of the thoracic cavity
to decrease and the pressure ofcthe thoracic cavity to
increase.
Lower atmospheric pressure inside the lungs forces the air out of the lungs.
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