1
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
2
3
The answer is…
4
…still a
mystery.
5
1
Which parts of
our body are in action
when we yawn
6
2
Where does the
exchange of oxygen
and carbon dioxide
take place between
our body and the
atmosphere
7
3
In what forms
are oxygen and
carbon dioxide
carried around our
body
8
7.1 The human breathing
system
gas exchange (氣體交換)
O2
CO2
9
7.1 The human breathing system
In very small organisms:
O2
CO2
• diffuses across cell membrane
10
7.1 The human breathing system
In larger organisms:


O2
CO2
• cannot diffuse across body surface
11
7.1 The human breathing system
In larger organisms:
• breathing system (呼吸系統)
- for gas exchange
• transport system (運送系統)
- for carrying gases to body cells
12
7.1 The human breathing system
What does the
human breathing
system consist of?
13
7.1 The human breathing system
Human breathing system
3D Model
nostril
epiglottis
bronchiole
air sac
nasal cavity
pharynx
larynx
trachea
bronchus
lung
14
7.1 The human breathing system
Human breathing system
rib
diaphragm
15
7.1 The human breathing system
Human breathing system
intercostal
muscle
pleural
cavity
outer pleural
membrane
inner pleural
membrane
16
7.1 The human breathing system
air
How does air flow
into the lungs?
17
7.1 The human breathing system
air
nasal cavity
pharynx
larynx
trachea
18
7.1 The human breathing system
air
bronchus
bronchiole
air sac
19
7.1 The human breathing system
7.1
Examination of the mammalian
breathing system
1 Examine the breathing system
of a dissected rat or a human
torso model.
2 Identify the various structures.
20
7.1 The human breathing system
1 Nostrils and nasal cavity
i) Hairs
• filter larger dust particles
21
7.1 The human breathing system
1 Nostrils and nasal cavity
ii) Mucus-secreting cells
traps dust particles & moistens air
mucus
22
7.1 The human breathing system
1 Nostrils and nasal cavity
iii) Ciliated epithelial cells
sweep mucus with dust particles
towards pharynx
cilia
23
7.1 The human breathing system
1 Nostrils and nasal cavity
iv) Capillaries
• blood warms up air
24
7.1 The human breathing system
2 Pharynx and larynx
pharynx
larynx
oesophagus
trachea
25
7.1 The human breathing system
2 Pharynx and larynx
food
larynx
oesophagus
26
7.1 The human breathing system
2 Pharynx and larynx
1 Tongue pushes
food towards
pharynx
larynx
oesophagus
27
7.1 The human breathing system
2 Pharynx and larynx
2 Soft palate moves
up, preventing
food from entering
nasal cavity
larynx
oesophagus
28
7.1 The human breathing system
2 Pharynx and larynx
3 Larynx rises and
epiglottis covers
entrance to trachea,
preventing choking
larynx
oesophagus
29
7.1 The human breathing system
2 Pharynx and larynx
30
7.1 The human breathing system
2 Pharynx and larynx
epiglottis
larynx
• made up
of cartilage
31
7.1 The human breathing system
2 Pharynx and larynx
vocal cords (聲帶)
• can vibrate to
produce sound
32
7.1 The human breathing system
3 Trachea, bronchi and
bronchioles
trachea
bronchus
bronchioles
33
7.1 The human breathing system
3 Trachea, bronchi and
bronchioles
trachea
bronchus
bronchioles
34
7.1 The human breathing system
3 Trachea, bronchi and
bronchioles
lumen
C-shaped cartilage
• prevents
collapse
ciliated epithelial
cell
35
7.1 The human breathing system
3 Trachea, bronchi and
bronchioles
Ciliated epithelial cells
Trachea
Bronchi
Bronchiole
36
7.1 The human breathing system
3 Trachea, bronchi and
bronchioles
Mucus-secreting cells
Trachea
Bronchi
Bronchiole
Absent in smaller
bronchioles
37
7.1 The human breathing system
3 Trachea, bronchi and
bronchioles
Capillaries
Trachea
Bronchi
Bronchiole
38
7.1 The human breathing system
3 Trachea, bronchi and
bronchioles
Cartilage
Trachea
C-shaped
Bronchi
Circular
Bronchiole
Absent
39
7.1 The human breathing system
4 Air sacs
• large respiratory surface
air sac
capillary
40
7.1 The human breathing system
5 Lungs
• composed of bronchioles and air sacs
• in thoracic cavity (胸腔)
41
7.1 The human breathing system
5 Lungs
• protected by rib cage (肋骨籃)
vertebral
column (脊柱)
ribs
cartilage
sternum
(胸骨)
42
7.1 The human breathing system
5 Lungs
diaphragm
• sheet of
muscle
intercostal
muscles
43
7.1 The human breathing system
5 Lungs
44
7.1 The human breathing system
5 Lungs
rib
intercostal muscle
outer pleural membrane
inner pleural membrane
right
lung
pleural cavity
45
7.1 The human breathing system
5 Lungs
• pleural cavity filled with
pleural fluid (胸腺液)
as lubricant
(潤滑劑)
right
lung
pleural cavity
46
7.1 The human breathing system
7.2
Examination of the pig lungs
1 Examine the pig lungs.
Identify the larynx,
epiglottis, trachea,
bronchi, left and right
lungs.
47
7.1 The human breathing system
7.2
2 The lungs have several lobes. Find out the
number of lobes present in the left and the
right lungs respectively.
48
7.1 The human breathing system
7.2
3 Feel the hardness of the trachea and the
lung tissue with a pair of forceps.
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.
49
7.1 The human breathing system
1a The human breathing system
consists of the respiratory tract
and structures that aid breathing.
50
7.1 The human breathing system
1b Air flow along respiratory tract:
nostrils
nasal cavity
pharynx
larynx
trachea
bronchi
bronchioles
air sacs
51
7.1 The human breathing system
2a In the nostrils,
hairs filter
larger dust particles.
52
7.1 The human breathing system
2b In the lining of nasal cavity,
trachea, bronchi and bronchioles,
mucus-secreting
cells secrete
mucus-secreting
cells
mucus
mucus to moisten the air.
53
7.1 The human breathing system
2c In the lining of nasal cavity,
trachea, bronchi and bronchioles,
mucus
mucus traps the dust particles
and bacteria.
54
7.1 The human breathing system
2d In the lining of nasal cavity,
trachea, bronchi and bronchioles,
blood in the capillaries
blood
warms the incoming air.
55
7.2 Gas exchange in the air sacs
Respiratory gases
Oxygen
Carbon
dioxide
56
7.2 Gas exchange in the air sacs
Where does gas exchange
take place?
57
7.2 Gas exchange in the air sacs
in the air sacs
Where does gas exchange
take place?
58
7.2 Gas exchange in the air sacs
Uptake of oxygen by the blood
blood flow
capillary
air sac
59
7.2 Gas exchange in the air sacs
Uptake of oxygen by the blood
1 O2 is inhaled.
blood flow
O2
60
7.2 Gas exchange in the air sacs
Uptake of oxygen by the blood
2 O2 dissolves in
water film.
blood flow
O2
61
7.2 Gas exchange in the air sacs
Uptake of oxygen by the blood
3 O2 diffuses into
red blood cells.
blood flow
O2
62
7.2 Gas exchange in the air sacs
Removal of carbon dioxide
blood flow
into the air sacs
1 CO2 diffuses
out from
capillary.
CO2
63
7.2 Gas exchange in the air sacs
Removal of carbon dioxide
blood flow
into the air sacs
2 CO2 diffuses
into air sacs.
CO2
64
7.2 Gas exchange in the air sacs
Removal of carbon dioxide
blood flow
into the air sacs
Animation
3 CO2 is
exhaled.
CO2
65
7.2 Gas exchange in the air sacs
Adaptive features of air sacs
1 Large number of air sacs
• provide large surface area for gas exchange
66
7.2 Gas exchange in the air sacs
Adaptive features of air sacs
2 Thin wall of air sac
• provides short
diffusion distance
air sac
one-cell thick
epithelium
67
7.2 Gas exchange in the air sacs
Adaptive features of air sacs
3 Water film lining inner surface
• keeps inner surface
moist to dissolve gases
water film
68
7.2 Gas exchange in the air sacs
Adaptive features of air sacs
4 Network of capillaries
• Rapid transport of gases
• Maintain steep air sac
concentration gradient
capillary
red blood cell
69
7.2 Gas exchange in the air sacs
7.3
Examination of the mammalian air sacs
1 Examine the slides or photomicrographs
of the mammalian lungs.
70
7.2 Gas exchange in the air sacs
7.3
2 Identify the air sacs.
air sac
capillary
71
7.2 Gas exchange in the air sacs
7.3
3 Draw a labelled diagram of the air sacs.
72
7.2 Gas exchange in the air sacs
1 How does gas exchange take place
in the air sacs?
Oxygen concentration in air sacs is
higher than that in the capillaries.
higher
73
7.2 Gas exchange in the air sacs
1 How does gas exchange take place
in the air sacs?
Oxygen in incoming air dissolves in
the water film lining the air sacs,
and then diffuses across the walls
of the air sacs and the capillaries
into the blood.
74
7.2 Gas exchange in the air sacs
1 How does gas exchange take place
in the air sacs?
Carbon dioxide concentration in
capillaries is higher than that in
air sacs.
75
7.2 Gas exchange in the air sacs
1 How does gas exchange take place
in the air sacs?
Carbon dioxide in blood diffuses
capillaries
across the walls of the capillaries
airsacs
sacs into the air in the
and the air
air sacs.
76
7.2 Gas exchange in the air sacs
2 Adaptive features of the air sacs:
Large number
largesurface
surfacearea
area
provides a large
for gas exchange
77
7.2 Gas exchange in the air sacs
2 Adaptive features of the air sacs:
Thin wall
provides a short distance
for rapid diffusion of gases
78
7.2 Gas exchange in the air sacs
2 Adaptive features of the air sacs:
Moist inner surface
allows gases to dissolve in
the water film for diffusion
79
7.2 Gas exchange in the air sacs
2 Adaptive features of the air sacs:
Network of capillaries
allows rapid transport of gases to
maintain a steep concentration
gradient for diffusion
80
7.2 Gas exchange in the air sacs
Quick check
The film of water on the surface of
human air sacs serves to
A.
B.
C.
D.
Warm the incoming air.
Moisten the incoming air.
Trap dust in the inhaled air.
Dissolve the gases in the inhaled air.
81
7.3 Transport of respiratory
gases
Oxygen in blood is
transported by…
82
7.3 Transport of respiratory
gases
Oxygen in blood is
transported by…
red blood cells
83
7.3 Transport of respiratory
gases
Oxygen is mainly transported
by red blood cells
84
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
85
7.3 Transport of respiratory gases
Adaptive features of red blood
cells for carrying oxygen
biconcave disc shape (雙凹圓盤狀):
surface area
cytoplasmic volume
86
7.3 Transport of respiratory gases
Adaptive features of red blood
cells for carrying oxygen
biconcave disc shape (雙凹圓盤狀):
short distance for diffusion
87
7.3 Transport of respiratory gases
Adaptive features of red blood
cells for carrying oxygen
without nucleus:
more room for haemoglobin
88
7.3 Transport of respiratory gases
Transport of oxygen
In lungs
air sac
O2
red blood cell
Hb + O2 → oxyhaemoglobin
In body cells
89
7.3 Transport of respiratory gases
Transport of oxygen
In lungs
O2
oxyhaemoglobin → Hb + O2
In body cells
90
7.3 Transport of respiratory gases
Transport of oxygen
In lungs
O2
O2
In body cells
91
7.3 Transport of respiratory gases
Transport of carbon dioxide
In lungs
CO2
In body cells
92
7.3 Transport of respiratory gases
Transport of carbon dioxide
In lungs
hydrogencarbonate ion
CO2 + H2O → H+ + HCO3In body cells
93
7.3 Transport of respiratory gases
Transport of carbon dioxide
In lungs
HCO3In body cells
94
7.3 Transport of respiratory gases
Transport of carbon dioxide
In lungs
H+ + HCO3- → H2O + CO2
In body cells
95
7.3 Transport of respiratory gases
Transport of carbon dioxide
In lungs
CO2
In body cells
96
7.3 Transport of respiratory gases
1 Adaptive features of red blood cells
for carrying oxygen:
Biconcave disc shape
surface area
area to
to
• increases surface
volume
volume ratio
97
7.3 Transport of respiratory gases
1 Adaptive features of red blood cells
for carrying oxygen:
Biconcave disc shape
• shortens diffusion
diffusionpath
path
for oxygen
98
7.3 Transport of respiratory gases
2 Transport of oxygen:
In air sacs, oxygen concentration
is high .
haemoglobin + oxygen
oxyhaemoglobin
carried by blood
99
7.3 Transport of respiratory gases
2 Transport of oxygen:
In body cells, oxygen concentration
is low .
oxyhaemoglobin
haemoglobin + oxygen
body cells
100
7.3 Transport of respiratory gases
3 Transport of carbon dioxide:
Carbon dioxide is produced by body
cells.
carbon dioxide + water
hydrogencarbonate ions (HCO3-)
carried in plasma
101
7.3 Transport of respiratory gases
3 Transport of carbon dioxide:
When blood reaches the air sacs,
hydrogencarbonate ions
carbon dioxide + water
air sacs
102
7.4 Ventilation
Ventilation (換氣)
brought about by
Breathing
involves
Inhalation
Exhalation
103
7.4 Ventilation
Inhalation
Animation
1a Intercostal
muscles
contract.
Rib cage moves
upwards and
outwards.
104
7.4 Ventilation
Inhalation
1b Diaphragm
muscles
contract.
Diaphragm
flattens.
105
7.4 Ventilation
Inhalation
2
Volume of
thoracic cavity
increases,
pressure
decreases.
106
7.4 Ventilation
Inhalation
3a Lungs expand.
3b Air pressure in
the lungs is
lower than
atmospheric
pressure.
107
7.4 Ventilation
Inhalation
4
air
Air rushes into
lungs.
108
7.4 Ventilation
Ventilation (換氣)
brought about by
Breathing
involves
Inhalation
Exhalation
109
7.4 Ventilation
Exhalation
1a Intercostal
muscles relax.
Rib cage moves
downwards and
inwards.
110
7.4 Ventilation
Exhalation
1b Diaphragm
muscles relax.
Diaphragm
returns to
dome shape.
111
7.4 Ventilation
Exhalation
2
Volume of
thoracic cavity
decreases,
pressure
increases.
112
7.4 Ventilation
Exhalation
3a Lungs recoil.
3b Air pressure in
the lungs is
higher than
atmospheric
pressure.
113
7.4 Ventilation
Exhalation
4
air
Air is forced
out of the
lungs.
114
7.4 Ventilation
air pressure in
thoracic cavity
atmospheric pressure
exhalation inhalation exhalation inhalation
time
115
7.4 Ventilation
respiration = breathing = ventilation
116
7.4 Ventilation
Respiration :
The chemical process of
releasing energy from food.
117
7.4 Ventilation
Breathing :
The mechanical process of
moving air into and out of the
breathing system.
118
7.4 Ventilation
Ventilation :
The movement of air over the
respiratory surface to faciliate
gas exchange.
119
7.4 Ventilation
What is the difference in
composition between
inhaled and exhaled air?
120
7.4 Ventilation
7.4
Comparison of the composition of
inhaled air and exhaled air
1 Collect two jars of
inhaled air (atmospheric
air) and two jars of
exhaled air as shown.
121
7.4 Ventilation
7.4
2 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.
122
7.4 Ventilation
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.
123
7.4 Ventilation
7.4
Results and discussion
The results show that
exhaled air contains less
oxygen but more
carbon dioxide than
inhaled air.
124
7.4 Ventilation
Oxygen
Inhaled air
21%
Exhaled air
16%
Used by body cells
Why
for respiration
different /
the same?
125
7.4 Ventilation
Carbon dioxide
Inhaled air
0.03%
Exhaled air
4%
Produced by body
Why
cells during respiration
different /
the same?
126
7.4 Ventilation
Nitrogen
Inhaled air
78%
Exhaled air
78%
Not used or
Why
produced by body
different /
the same? cells
127
7.4 Ventilation
Water vapour
Inhaled air
Variable
Exhaled air
Saturated
Moistened by mucus
Why
and water film
different /
the same?
128
7.4 Ventilation
Other gases
Inhaled air
Exhaled air
1%
1%
129
7.4 Ventilation
Temperature
Inhaled air
Cooler
Exhaled air
Warmer
Warmed by blood
Why
different /
the same?
130
7.4 Ventilation
• Inhaled air consists mainly
of oxygen.
• Exhaled air consists mainly
of carbon dioxide.
131
7.4 Ventilation
Both inhaled and exhaled air
consists mainly of nitrogen
(about 78%).
132
7.4 Ventilation
There is more carbon dioxide
than oxygen in exhaled air.
O2
CO2
133
7.4 Ventilation
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.
134
7.4 Ventilation
1 Ventilation involves inhalation and
exhalation . It is brought about by
ex
the movements of the rib cage
and the diaphragm .
135
7.4 Ventilation
Diaphragm
muscles
Diaphragm
Inhalation
Exhalation
Contract
Relax
Flattened
Dome
shape
136
7.4 Ventilation
Intercostal
muscles
Rib cage
Inhalation
Exhalation
Contract
Relax
Moves
upwards &
outwards
Moves
downwards
& inwards
137
7.4 Ventilation
Volume of
thoracic
cavity
Lungs
Inhalation
Exhalation
Increases
Decreases
Inflated
Deflated
138
7.4 Ventilation
Inhalation
Exhalation
Lower
than
Higher
than
Air pressure
atmospheric
atmospheric
in lungs
pressure
pressure
Direction of
air flow
Into the
lungs
Out of the
lungs
139
7.4 Ventilation
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.
140
1
Which parts of our body are in action
when we yawn?
Our mouth opens and we breathe in
deeply. The abdominal muscles are
stretched, the rib cage raises and the
diaphragm is pushed down.
141
2
Where does the exchange of oxygen
and carbon dioxide take place between
our body and the atmosphere?
The exchange of oxygen and carbon
dioxide takes place in the air sacs.
142
3
In what forms are oxygen and carbon
dioxide carried around our body?
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.
143
Gas exchange
takes place at
respiratory
surface (air sacs)
are parts of
human
breathing system
144
Gas exchange
facilitated by
ventilation
brought about by
breathing
145
breathing
involves
inhalation
exhalation
brought about by
contraction of
intercostal &
diaphragm
muscles
relaxation of
intercostal &
diaphragm
muscles
146
Gas exchange
include
oxygen
transported by
involves
diffusion of
respiratory gases
carbon dioxide
transported mainly as
haemoglobin in hydrogencarbonate
red blood cells
ions in plasma
147