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Think about…
7.1 The human breathing system
7.2 Gas exchange in the air sacs
7.3 Transport of respiratory gases
7.4 Ventilation
Recall ‘Think about…’
Summary concept map
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The answer is…
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…still a mystery.
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Which parts ofour body are in action when we yawn
1
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Where does the exchange of oxygen and carbon dioxide take place between our body and the atmosphere
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In what formsare oxygen and carbon dioxide carried around our body
3
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7.1 The human breathing system
O2 CO2
gas exchange (氣體交換 )
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• diffuses across cell membrane
7.1 The human breathing system
In very small organisms:
O2
CO2
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7.1 The human breathing system
In larger organisms:
• cannot diffuse across body surface
O2
CO2
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• breathing system (呼吸系統 )
• transport system (運送系統 )
7.1 The human breathing system
In larger organisms:
- for gas exchange
- for carrying gases to body cells
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What does the human breathing
system consist of?
7.1 The human breathing system
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7.1 The human breathing system
Human breathing system
pharynx
larynxtracheabronchus
lungair sac
bronchiole
epiglottis
nostrilnasal cavity3D Model
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rib
diaphragm
7.1 The human breathing system
Human breathing system
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7.1 The human breathing system
Human breathing system
intercostal muscle
inner pleural membrane
outer pleural membrane
pleural cavity
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7.1 The human breathing system
air
How does air flow into the lungs?
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7.1 The human breathing system
nasal cavity
pharynx
larynx
trachea
air
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7.1 The human breathing system
bronchus
bronchiole
air sac
air
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1 Examine the breathing system of a dissected rat or a human torso model.
7.1
Examination of the mammalian breathing system
7.1 The human breathing system
2 Identify the various structures.
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7.1 The human breathing system
1 Nostrils and nasal cavityi) Hairs
• filter larger dust particles
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7.1 The human breathing system
1 Nostrils and nasal cavityii) Mucus-secreting cells
mucustraps dust particles & moistens air
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7.1 The human breathing system
1 Nostrils and nasal cavityiii) Ciliated epithelial cells
cilia
sweep mucus with dust particles towards pharynx
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7.1 The human breathing system
1 Nostrils and nasal cavityiv) Capillaries
• blood warms up air
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2 Pharynx and larynx7.1 The human breathing system
larynx oesophagus
trachea
pharynx
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2 Pharynx and larynx7.1 The human breathing system
larynx
food
oesophagus
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2 Pharynx and larynx7.1 The human breathing system
larynx oesophagus
1 Tongue pushes food towards pharynx
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2 Pharynx and larynx7.1 The human breathing system
larynx oesophagus
2 Soft palate moves up, preventing food from entering nasal cavity
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2 Pharynx and larynx7.1 The human breathing system
larynx oesophagus
3 Larynx rises and epiglottis covers entrance to trachea, preventing choking
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7.1 The human breathing system
2 Pharynx and larynx
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7.1 The human breathing system
2 Pharynx and larynx
larynx
• made up of cartilage
epiglottis
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7.1 The human breathing system
2 Pharynx and larynx
vocal cords (聲帶 )• can vibrate to
produce sound
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7.1 The human breathing system
trachea
bronchus
bronchioles
3 Trachea, bronchi and bronchioles
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3 Trachea, bronchi and bronchioles
7.1 The human breathing system
bronchus
bronchioles
trachea
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3 Trachea, bronchi and bronchioles
7.1 The human breathing system
C-shaped cartilage
ciliated epithelial cell
lumen
• prevents collapse
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3 Trachea, bronchi and bronchioles
7.1 The human breathing system
Trachea
Bronchi
Bronchiole
Ciliated epithelial cells
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3 Trachea, bronchi and bronchioles
7.1 The human breathing system
Trachea
Bronchi
Bronchiole
Mucus-secreting cells
Absent in smaller bronchioles
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3 Trachea, bronchi and bronchioles
7.1 The human breathing system
Trachea
Bronchi
Bronchiole
Capillaries
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3 Trachea, bronchi and bronchioles
7.1 The human breathing system
Trachea
Bronchi
Bronchiole
Cartilage
Absent
C-shaped
Circular
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7.1 The human breathing system
4 Air sacs
air sac
• large respiratory surface
capillary
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7.1 The human breathing system
5 Lungs
• in thoracic cavity (胸腔 )• composed of bronchioles and air sacs
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7.1 The human breathing system
5 Lungs• protected by rib cage (肋骨籃 )
ribs
cartilage
vertebral column (脊柱 )
sternum (胸骨 )
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7.1 The human breathing system
5 Lungs
intercostal musclesdiaphragm
• sheet of muscle
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7.1 The human breathing system
5 Lungs
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7.1 The human breathing system
5 Lungs
right lung
ribintercostal muscle
outer pleural membraneinner pleural membrane
pleural cavity
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7.1 The human breathing system
5 Lungs
right lung
pleural cavity
• pleural cavity filled with pleural fluid (胸腺液 )
as lubricant (潤滑劑 )
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1 Examine the pig lungs. Identify the larynx, epiglottis, trachea, bronchi, left and right lungs.
7.2
Examination of the pig lungs
7.1 The human breathing system
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7.2
2 The lungs have several lobes. Find out the number of lobes present in the left and the right lungs respectively.
7.1 The human breathing system
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7.2
3 Feel the hardness of the trachea and the lung tissue with a pair of forceps.
7.1 The human breathing system
4 Use a water hose to fill the lungs with water through the trachea. Note the changes in the volume of the lungs.
5 Draw a labelled diagram of the lungs.
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1a The human breathing system consists of the and structures that aid breathing.
respiratory tract
7.1 The human breathing system
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air sacs
bronchi
larynx
nasal cavity
bronchioles
pharynx
nostrils
trachea
1b Air flow along respiratory tract:
7.1 The human breathing system
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2a In the nostrils, filter larger dust particles.
7.1 The human breathing system
hairs
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2b In the lining of nasal cavity, trachea, bronchi and bronchioles, mucus-secreting cells secrete mucus to moisten the air. mucusmucus-secreting cells
7.1 The human breathing system
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2c In the lining of nasal cavity, trachea, bronchi and bronchioles,
mucus traps the dust particles and bacteria.
7.1 The human breathing system
mucus
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2d In the lining of nasal cavity, trachea, bronchi and bronchioles, blood in the warms the incoming air.
7.1 The human breathing system
blood capillaries
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7.2 Gas exchange in the air sacs
Respiratory gases
OxygenCarbon dioxide
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7.2 Gas exchange in the air sacs
Where does gas exchange take place?
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7.2 Gas exchange in the air sacs
in the air sacs
Where does gas exchange take place?
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7.2 Gas exchange in the air sacs
blood flow
air sac
capillary
Uptake of oxygen by the blood
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7.2 Gas exchange in the air sacs
blood flowUptake of oxygen by the blood
1 O2 is inhaled.
O2
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7.2 Gas exchange in the air sacs
blood flowUptake of oxygen by the blood
2 O2 dissolves in water film.
O2
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7.2 Gas exchange in the air sacs
blood flowUptake of oxygen by the blood
3 O2 diffuses into red blood cells.
O2
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7.2 Gas exchange in the air sacs
blood flowRemoval of carbon dioxide into the air sacs
1 CO2 diffuses out from capillary.
CO2
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7.2 Gas exchange in the air sacs
blood flowRemoval of carbon dioxide into the air sacs
2 CO2 diffuses into air sacs.
CO2
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7.2 Gas exchange in the air sacs
blood flowRemoval of carbon dioxide into the air sacs
3 CO2 is exhaled.
CO2
Animation
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Adaptive features of air sacs7.2 Gas exchange in the air sacs
1 Large number of air sacs• provide large surface area for gas exchange
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Adaptive features of air sacs7.2 Gas exchange in the air sacs
2 Thin wall of air sac• provides short
diffusion distance
air sac
one-cell thick epithelium
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Adaptive features of air sacs7.2 Gas exchange in the air sacs
3 Water film lining inner surface• keeps inner surface
moist to dissolve gases
water film
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Adaptive features of air sacs7.2 Gas exchange in the air sacs
4 Network of capillaries• Rapid transport of gases
• Maintain steep concentration gradient
air sac
capillary
red blood cell
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1 Examine the slides or photomicrographs of the mammalian lungs.
7.3
Examination of the mammalian air sacs
7.2 Gas exchange in the air sacs
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7.3
2 Identify the air sacs.
air sac
capillary
7.2 Gas exchange in the air sacs
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7.3
3 Draw a labelled diagram of the air sacs.
7.2 Gas exchange in the air sacs
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Oxygen concentration in air sacs is higher than that in the capillaries.
1 How does gas exchange take place in the air sacs?
higher
7.2 Gas exchange in the air sacs
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Oxygen in incoming air dissolves in the lining the air sacs, and then across the walls of the air sacs and the capillaries into the blood.
1 How does gas exchange take place in the air sacs?
diffuseswater film
7.2 Gas exchange in the air sacs
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Carbon dioxide concentration in capillaries is than that in air sacs.
higher
1 How does gas exchange take place in the air sacs?
7.2 Gas exchange in the air sacs
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Carbon dioxide in blood diffuses across the walls of the capillaries and the air sacs into the air in the air sacs.
capillariesair sacs
1 How does gas exchange take place in the air sacs?
7.2 Gas exchange in the air sacs
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provides a large surface area for gas exchange
2 Adaptive features of the air sacs:
Large number
large surface area
7.2 Gas exchange in the air sacs
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provides a for rapid diffusion of gases
2 Adaptive features of the air sacs:
Thin wall
short distance
7.2 Gas exchange in the air sacs
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allows gases to in the water film for diffusion
dissolve
2 Adaptive features of the air sacs:
Moist inner surface
7.2 Gas exchange in the air sacs
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allows rapid transport of gases to maintain a for diffusion gradient
2 Adaptive features of the air sacs:
Network of capillaries
steep concentration
7.2 Gas exchange in the air sacs
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A. Warm the incoming air.B. Moisten the incoming air.C. Trap dust in the inhaled air.D. Dissolve the gases in the inhaled air.
Quick check
The film of water on the surface of human air sacs serves to
7.2 Gas exchange in the air sacs
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Oxygen in blood is transported by…
7.3 Transport of respiratory gases
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83red blood cells
7.3 Transport of respiratory gases
Oxygen in blood is transported by…
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Oxygen is mainly transported by red blood cells
7.3 Transport of respiratory gases
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7.3 Transport of respiratory gases
Adaptive features of red blood cells for carrying oxygen
fully packed with haemoglobin (血紅蛋白 )
oxygen carrier
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7.3 Transport of respiratory gases
biconcave disc shape (雙凹圓盤狀 ):
Adaptive features of red blood cells for carrying oxygen
surface area cytoplasmic volume
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7.3 Transport of respiratory gases
short distance for diffusion
Adaptive features of red blood cells for carrying oxygen
biconcave disc shape (雙凹圓盤狀 ):
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7.3 Transport of respiratory gases
without nucleus:
Adaptive features of red blood cells for carrying oxygen
more room for haemoglobin
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7.3 Transport of respiratory gases
Transport of oxygenIn lungs
In body cells
O2
air sac red blood cell
Hb + O2 → oxyhaemoglobin
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7.3 Transport of respiratory gases
Transport of oxygenIn lungs
In body cells
O2
oxyhaemoglobin → Hb + O2
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7.3 Transport of respiratory gases
Transport of oxygenIn lungs
In body cells
O2
O2
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7.3 Transport of respiratory gases
Transport of carbon dioxideIn lungs
In body cells
CO2
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7.3 Transport of respiratory gases
Transport of carbon dioxideIn lungs
In body cells
CO2 + H2O → H+ + HCO3-
hydrogencarbonate ion
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7.3 Transport of respiratory gases
Transport of carbon dioxideIn lungs
In body cells
HCO3-
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7.3 Transport of respiratory gases
Transport of carbon dioxideIn lungs
In body cells
H+ + HCO3- → H2O + CO2
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7.3 Transport of respiratory gases
Transport of carbon dioxideIn lungs
In body cells
CO2
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• increases surface area to volume ratio
1 Adaptive features of red blood cells for carrying oxygen:
7.3 Transport of respiratory gases
shapeBiconcave disc
volumesurface area to
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1 Adaptive features of red blood cells for carrying oxygen:
• shortens diffusion path for oxygen
7.3 Transport of respiratory gases
shapeBiconcave disc
diffusion path
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In air sacs, oxygen concentration is .
oxyhaemoglobin
haemoglobin
high
7.3 Transport of respiratory gases
+ oxygen
carried by blood
2 Transport of oxygen:
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haemoglobin
oxyhaemoglobin
lowIn body cells, oxygen concentration is .
7.3 Transport of respiratory gases
+ oxygen
body cells
2 Transport of oxygen:
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plasma
hydrogencarbonate ions (HCO3-)
carbon dioxide
3 Transport of carbon dioxide:
7.3 Transport of respiratory gases
+ water
carried in
Carbon dioxide is produced by body cells.
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watercarbon dioxide
3 Transport of carbon dioxide:
7.3 Transport of respiratory gases
+
air sacs
hydrogencarbonate ions
When blood reaches the air sacs,
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7.4 Ventilation
Ventilation (換氣 )
ExhalationInhalation
Breathing
involves
brought about by
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7.4 Ventilation
InhalationAnimation
1a Intercostal muscles contract.Rib cage moves upwards and outwards.
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7.4 Ventilation
Inhalation
1b Diaphragm muscles contract.Diaphragm flattens.
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7.4 Ventilation
Inhalation
2 Volume of thoracic cavity increases, pressure decreases.
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7.4 Ventilation
Inhalation
3b Air pressure in the lungs is lower than atmospheric pressure.
3a Lungs expand.
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7.4 Ventilation
Inhalation
4 Air rushes into lungs.
air
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7.4 Ventilation
Ventilation (換氣 )
ExhalationInhalation
Breathing
involves
brought about by
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7.4 Ventilation
Exhalation
1a Intercostal muscles relax.Rib cage moves downwards and inwards.
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7.4 Ventilation
Exhalation
1b Diaphragm muscles relax.Diaphragm returns to dome shape.
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7.4 Ventilation
Exhalation
2 Volume of thoracic cavity decreases, pressure increases.
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7.4 Ventilation
Exhalation
3b Air pressure in the lungs is higher than atmospheric pressure.
3a Lungs recoil.
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7.4 Ventilation
Exhalation air
4 Air is forced out of the lungs.
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7.4 Ventilation
air pressure in thoracic cavity
time
atmospheric pressure
exhalation inhalation exhalation inhalation
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respiration = breathing = ventilation
7.4 Ventilation
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Respiration :
The chemical process of releasing energy from food.
7.4 Ventilation
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Breathing :
The mechanical process of moving air into and out of the breathing system.
7.4 Ventilation
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Ventilation :
The movement of air over the respiratory surface to faciliate gas exchange.
7.4 Ventilation
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7.4 Ventilation
What is the difference in composition between
inhaled and exhaled air?
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1 Collect two jars of inhaled air (atmospheric air) and two jars of exhaled air as shown.
7.4
Comparison of the composition of inhaled air and exhaled air
7.4 Ventilation
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7.42 Lower a burning candle quickly into one jar
of inhaled air. Close the jar and record how long the candle can burn. Repeat with one jar of exhaled air.
7.4 Ventilation
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7.4
3 Add 10 cm3 of red hydrogencarbonate indicator into one jar of inhaled air. Close the jar and shake. Note any colour change. Repeat with one jar of exhaled air.
7.4 Ventilation
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7.4
7.4 Ventilation
Results and discussion
The results show that exhaled air contains less oxygen but more carbon dioxide than inhaled air.
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Oxygen7.4 Ventilation
Inhaled air
Exhaled air
Why different / the same?
21%
16%
Used by body cells for respiration
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Carbon dioxide7.4 Ventilation
Inhaled air
Exhaled air
Why different / the same?
0.03%
4%
Produced by body cells during respiration
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Nitrogen7.4 Ventilation
Inhaled air
Exhaled air
Why different / the same?
78%
78%
Not used or produced by body cells
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Water vapour7.4 Ventilation
Inhaled air
Exhaled air
Why different / the same?
Variable
Saturated
Moistened by mucus and water film
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Other gases7.4 Ventilation
Inhaled air
Exhaled air
1%
1%
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Temperature7.4 Ventilation
Inhaled air
Exhaled air
Why different / the same?
Cooler
Warmer
Warmed by blood
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• Inhaled air consists mainly of oxygen.
7.4 Ventilation
• Exhaled air consists mainly of carbon dioxide.
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Both inhaled and exhaled air consists mainly of nitrogen (about 78%).
7.4 Ventilation
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There is more carbon dioxide than oxygen in exhaled air.
CO2
O2 7.4 Ventilation
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Exhaled air contains a higher proportion of carbon dioxide when compared with that in inhaled air, its absolute amount (in terms of %) is still lower than that of oxygen.
7.4 Ventilation
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1 Ventilation involves and ex . It is brought about by the movements of the and the .
inhalation
diaphragm
exhalationrib cage
7.4 Ventilation
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7.4 Ventilation
Inhalation Exhalation
Diaphragm muscles
Diaphragm
Contract Relax
Flattened Dome shape
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7.4 Ventilation
Inhalation Exhalation
Intercostal muscles
Rib cage
Contract Relax
Moves upwards & outwards
Moves downwards & inwards
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7.4 Ventilation
Inhalation Exhalation
Volume of thoracic cavity
Lungs
Increases Decreases
Inflated Deflated
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7.4 Ventilation
Inhalation Exhalation
Air pressure in lungs
Lower than atmospheric
pressure
Higher than atmospheric
pressure
Direction of air flow
Into the lungs
Out of the lungs
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2 Exhaled air contains more / less O2 than inhaled air.
Its CO2 content is higher / lower than that in inhaled air.
Exhaled / Inhaled air is saturated with water vapour.
7.4 Ventilation
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Which parts of our body are in actionwhen we yawn?1
Our mouth opens and we breathe in deeply. The abdominal muscles are stretched, the rib cage raises and the diaphragm is pushed down.
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Where does the exchange of oxygenand carbon dioxide take place between our body and the atmosphere?
2
The exchange of oxygen and carbon dioxide takes place in the air sacs.
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In what forms are oxygen and carbondioxide carried around our body?3
Oxygen is transported mainly in form of oxyhaemoglobin in red blood cells. Carbon dioxide is transported mainly in form of hydrogencarbonate ions dissolved in plasma.
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Gas exchange
respiratory surface (air sacs)
human breathing system
are parts of
takes place at
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Gas exchange
ventilation
breathing
brought about by
facilitated by
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involvesbreathing
inhalation exhalation
contraction of intercostal &
diaphragm muscles
relaxation of intercostal & diaphragm muscles
brought about by
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Gas exchange
respiratory gasesinclude
involves diffusion of
oxygen carbon dioxide
haemoglobin in red blood cells
hydrogencarbonate ions in plasma
transported by transported mainly as