CHAPTER 8 : RESPIRATORY SYSTEM IN HUMAN AND ANIMALS

CHAPTER 8
RESPIRATORY SYSTEMS

IN HUMANS AND
ANIMALS

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8.1 TYPES OF RESPIRATORY SYSTEM

Respiratory Structures and Their Adaptations for Gaseous Exchange

▪ Respiratory Structure is the respiratory surface that enables gaseous exchange to
occur between respiring organism cells and their outer environment

▪ Unicellular organisms do not have special respiratory structure because it has large
total surface area to volume ratio for gaseous exchange through diffusion

▪ Bigger size : smaller the ratio of total surface area to volume
▪ Smaller size : bigger the ration of total surface area to volume
▪ Large and complex organisms, the volume of the body that requires oxygen will

increase more than its total surface area
▪ Large and complex organisms cannot maintain gaseous exchange by diffusion

through body only
▪ Need special respiratory structure for the efficient exchange of gases

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Respiratory Structures and Their Adaptations for Gaseous Exchange

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The Insect Respiratory Structure and Its Adaptations

✓ Breathing system : Tracheal System
✓ N : Spiracle

C : small pores in the thorax and abdomen
F : allows the intake of air into the air tube system
✓ N : Tracheole
C : branches out from trachea to form finer tube
F : to increase efficiency of respiratory gaseous change
✓ N : Tracheole
C : numerous // a large number
F : provides a large total surface area for the exchange
of gases
✓ N : Tracheole
C : Thin and moist wall
F : allow oxygen gas to diffuse into the cells while

carbon dioxide quickly diffuses out of the cells into
the tracheole
✓ N : some insect have air sac
C : filled with air
F : to speed up the delivery of respiratory gas during active body
movement

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The Fish Respiratory Structure and Its Adaptations

✓ Respiratory structure : Gills
✓ N : Gills

C : made up of a line of filament that is supported by
the gill arch

✓ N : Filament
C : has many thin and flat projection
F : to increase efficiency of respiratory gaseous change

✓ N : Lamella
C : numerous // a large number
F : provides a large total surface area for the exchange
of gases

✓ N : Lamella
C : Thin
F : easy absorption of gases

✓ N : Lamella
C : many blood capillaries
F : increase transport of oxygen and carbon dioxide

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The Frog Respiratory Structure and Its Adaptations

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The Human Respiratory Structure and Its Adaptations

C : Moist wall of alveolus C : Surrounded by the network of blood
F : Allow respiratory gases to dissolve and diffuse capillaries

into the blood capillaries F : to hasten the diffusion of respiratory gases
to increase the transportation of gases

C : Numerous of alveoli
F : Provide a large surface area for the exchange

of gases

C : The alveolus and blood capillaries have thin PREPARED BY CIKGU HUSRITA MRMS TRANSKRIAN
walls which are made up of only one cell thick

F : Facilitates and increases the rate of diffusion of gases
across the walls of the alveolus and blood capillaries

Comparison and Contrast of Respiratory Structures in Humans and
Animals

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8.2 MECHANISMS OF BREATHING

BREATHING : refers to the repetitive inhalation and exhalation process

BREATHING MECHANIMS OF INSECTS: INHALATION MECHANIMS OF INSECTS:
1. Abdominal muscle will relax
2. The air pressure in the trachea reduce
3. Air enters into the trachea through the

spiracle

EXHALATION MECHANIMS OF INSECTS:
1. Abdominal muscle will contract
2. The air pressure in the trachea increase
3. Air forces out through the spiracle

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BREATHING MECHANIMS OF FROGS: FROG : breathe through the mouth and lungs while in
an active state

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BREATHING MECHANIMS OF FISH : FISH :
✓ Aided by its mouth movement and operculum.
✓ Ventilation takes place when the fish swims by opening

and closing its operculum
✓ This pushes water into the mouth and subsequently

through the gills
✓ The ventilation increases the flow of water in the

respiratory surface

Operculum
Gills

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BREATHING MECHANIMS OF FISH :

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BREATHING MECHANIMS OF HUMANS:

INHALATION

1) External intercostal muscle contract

2) Internal intercostal muscle relax
3) Rib cage is pulled upwards & outwards
4) Diaphragm muscle contract
5) Diaphragm moves downward & flattens
6) Thoracic cavity volume increases
7) Air pressure in lungs decreases
8) The higher atmospheric pressure from outside

forces air into the lungs
9) The lungs expand

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EXHALATION

1) External intercostal muscle relax

2) Internal intercostal muscle contract
3) Rib cage is pulled downwards &

inwards
4) Diaphragm muscle relax
5) Diaphragm moves curve upwards &

dome shape
6) Thoracic volume decreases
7) Air pressure in lungs increases
8) Air is exhaled out of the lung
9) Volume of lungs decreases
10) The lungs return to its original

volume

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Compare and contrast breathing mechanisms in humans and animals

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8.3 GASEOUS EXCHANGE IN HUMANS

Partial pressure of oxygen and carbon dioxide:

➢Gas diffusion depends on the partial pressure difference
between two areas

➢The gas diffuses from an area where its partial pressure is
higher to an area where its partial pressure is lower,
which is down a partial pressure gradient

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Gaseous
Exchange
And The
Transport Of
Respiratory

Gases

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Transport of carbon dioxide in the blood circulatory system
Carbon dioxide is transported in three ways :
• 70% is carried in the form of bicarbonate ion (HCO3-)
• 23% carbon dioxide combines with haemoglobin to form

carbaminohaemoglobin
• 7% is dissolved and carried as carbonic acid (H2CO3)

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Transport of carbon dioxide in the blood circulatory system

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Transport of carbon dioxide in the blood circulatory system

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8.4 HEALTH ISSUES RELATED TO THE HUMAN RESPIRATORY SYSTEM

Chronic Obstructive Pulmonary Disease (COPD) comprises asthma, chronic bronchitis and emphysema

EMPHYSEMA
✓ The alveolus loses its elasticity and increases in size
✓ Is the condition of the alveoli in the lungs which are
damaged by harmful substances in the air such as irritants

in cigarette smoke
✓ The surface area of alveolus decreases and gaseous

exchange become less efficient
✓ Symptoms include shortness breath, pain when breathing

and feeling tired from doing even a light task
✓ Emphysema patients cannot be cured but the symptoms

of this disease can be controlled

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CHRONIC BRONCHITIS ASTHMA

✓ Is inflammation of the bronchiole, swollen and ✓ The bronchiole walls become swollen and
blocked thick

✓ This reduces the flow of air and causes ✓ The opening of the bronchiole tube
difficulties in breathing becomes smaller and the air passage
becomes narrower
✓ A large amount of mucus formed will cause
continuous coughing ✓ This condition leads to difficulties in
breathing and causes breathlessness
✓ Damage cilium causes difficulty in expelling
mucus ✓ Is triggered by the presence of dust, pollen,
haze, smoke from cigarette and motor
✓ caused by tar and irritants in cigarette smoke vehicle exhaust, open burning and forest
✓ Symptoms include shortness of breath, fires
persistent coughing and insomnia
✓ The symptoms include shortness of breath,
wheezing and coughing

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