think about… 7.1 the human breathing system 7.2 gas exchange in the air sacs

2

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

4

The answer is…

5

…still a mystery.

6

Which parts ofour body are in action when we yawn

1

7

Where does the exchange of oxygen and carbon dioxide take place between our body and the atmosphere

2

8

In what formsare oxygen and carbon dioxide carried around our body

3

9


O2 CO2

gas exchange (氣體交換 )

10

• diffuses across cell membrane


In very small organisms:

O2

CO2

11


In larger organisms:

• cannot diffuse across body surface

O2

CO2

12

• breathing system (呼吸系統 )

• transport system (運送系統 )


In larger organisms:

- for gas exchange

- for carrying gases to body cells

13

What does the human breathing

system consist of?


14


Human breathing system

pharynx

larynxtracheabronchus

lungair sac

bronchiole

epiglottis

nostrilnasal cavity3D Model

15

rib

diaphragm



16



intercostal muscle

inner pleural membrane

outer pleural membrane

pleural cavity

17


air

How does air flow into the lungs?

18


nasal cavity

pharynx

larynx

trachea

air

19


bronchus

bronchiole

air sac

air

20

1 Examine the breathing system of a dissected rat or a human torso model.

7.1

Examination of the mammalian breathing system


2 Identify the various structures.

21


1 Nostrils and nasal cavityi) Hairs

• filter larger dust particles

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1 Nostrils and nasal cavityii) Mucus-secreting cells

mucustraps dust particles & moistens air

23


1 Nostrils and nasal cavityiii) Ciliated epithelial cells

cilia

sweep mucus with dust particles towards pharynx

24


1 Nostrils and nasal cavityiv) Capillaries

• blood warms up air

25

2 Pharynx and larynx7.1 The human breathing system

larynx oesophagus

trachea

pharynx

26


larynx

food

oesophagus

27


larynx oesophagus

1 Tongue pushes food towards pharynx

28


larynx oesophagus

2 Soft palate moves up, preventing food from entering nasal cavity

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larynx oesophagus

3 Larynx rises and epiglottis covers entrance to trachea, preventing choking

30


2 Pharynx and larynx

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larynx

• made up of cartilage

epiglottis

32



vocal cords (聲帶 )• can vibrate to

produce sound

33


trachea

bronchus

bronchioles

3 Trachea, bronchi and bronchioles

34



bronchus

bronchioles

trachea

35



C-shaped cartilage

ciliated epithelial cell

lumen

• prevents collapse

36



Trachea

Bronchi

Bronchiole

Ciliated epithelial cells

37



Trachea

Bronchi

Bronchiole

Mucus-secreting cells

Absent in smaller bronchioles

38



Trachea

Bronchi

Bronchiole

Capillaries

39



Trachea

Bronchi

Bronchiole

Cartilage

Absent

C-shaped

Circular

40


4 Air sacs

air sac

• large respiratory surface

capillary

41


5 Lungs

• in thoracic cavity (胸腔 )• composed of bronchioles and air sacs

42


5 Lungs• protected by rib cage (肋骨籃 )

ribs

cartilage

vertebral column (脊柱 )

sternum (胸骨 )

43


5 Lungs

intercostal musclesdiaphragm

• sheet of muscle

44


5 Lungs

45


5 Lungs

right lung

ribintercostal muscle

outer pleural membraneinner pleural membrane

pleural cavity

46


5 Lungs

right lung

pleural cavity

• pleural cavity filled with pleural fluid (胸腺液 )

as lubricant (潤滑劑 )

47

1 Examine the pig lungs. Identify the larynx, epiglottis, trachea, bronchi, left and right lungs.

7.2

Examination of the pig lungs


48

7.2

2 The lungs have several lobes. Find out the number of lobes present in the left and the right lungs respectively.


49

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.

50

1a The human breathing system consists of the and structures that aid breathing.

respiratory tract


51

air sacs

bronchi

larynx

nasal cavity

bronchioles

pharynx

nostrils

trachea

1b Air flow along respiratory tract:


52

2a In the nostrils, filter larger dust particles.


hairs

53

2b In the lining of nasal cavity, trachea, bronchi and bronchioles, mucus-secreting cells secrete mucus to moisten the air. mucusmucus-secreting cells


54

2c In the lining of nasal cavity, trachea, bronchi and bronchioles,

mucus traps the dust particles and bacteria.


mucus

55

2d In the lining of nasal cavity, trachea, bronchi and bronchioles, blood in the warms the incoming air.


blood capillaries

56


Respiratory gases

OxygenCarbon dioxide

57


Where does gas exchange take place?

58


in the air sacs

Where does gas exchange take place?

59


blood flow

air sac

capillary

Uptake of oxygen by the blood

60


blood flowUptake of oxygen by the blood

1 O2 is inhaled.

O2

61



2 O2 dissolves in water film.

O2

62



3 O2 diffuses into red blood cells.

O2

63


blood flowRemoval of carbon dioxide into the air sacs

1 CO2 diffuses out from capillary.

CO2

64



2 CO2 diffuses into air sacs.

CO2

65



3 CO2 is exhaled.

CO2

Animation

66

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

67


2 Thin wall of air sac• provides short

diffusion distance

air sac

one-cell thick epithelium

68


3 Water film lining inner surface• keeps inner surface

moist to dissolve gases

water film

69


4 Network of capillaries• Rapid transport of gases

• Maintain steep concentration gradient

air sac

capillary

red blood cell

70

1 Examine the slides or photomicrographs of the mammalian lungs.

7.3

Examination of the mammalian air sacs


71

7.3

2 Identify the air sacs.

air sac

capillary


72

7.3

3 Draw a labelled diagram of the air sacs.


73

Oxygen concentration in air sacs is higher than that in the capillaries.

1 How does gas exchange take place in the air sacs?

higher


74

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.


diffuseswater film


75

Carbon dioxide concentration in capillaries is than that in air sacs.

higher



76

Carbon dioxide in blood diffuses across the walls of the capillaries and the air sacs into the air in the air sacs.

capillariesair sacs



77

provides a large surface area for gas exchange

2 Adaptive features of the air sacs:

Large number

large surface area


78

provides a for rapid diffusion of gases


Thin wall

short distance


79

allows gases to in the water film for diffusion

dissolve


Moist inner surface


80

allows rapid transport of gases to maintain a for diffusion gradient


Network of capillaries

steep concentration


81

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


82

Oxygen in blood is transported by…


83red blood cells


Oxygen in blood is transported by…

84

Oxygen is mainly transported by red blood cells


85


Adaptive features of red blood cells for carrying oxygen

fully packed with haemoglobin (血紅蛋白 )

oxygen carrier

86


biconcave disc shape (雙凹圓盤狀 ):


surface area cytoplasmic volume

87


short distance for diffusion


biconcave disc shape (雙凹圓盤狀 ):

88


without nucleus:


more room for haemoglobin

89


Transport of oxygenIn lungs

In body cells

O2

air sac red blood cell

Hb + O2 → oxyhaemoglobin

90



In body cells

O2

oxyhaemoglobin → Hb + O2

91



In body cells

O2

O2

92


Transport of carbon dioxideIn lungs

In body cells

CO2

93



In body cells

CO2 + H2O → H+ + HCO3-

hydrogencarbonate ion

94



In body cells

HCO3-

95



In body cells

H+ + HCO3- → H2O + CO2

96



In body cells

CO2

97

• increases surface area to volume ratio

1 Adaptive features of red blood cells for carrying oxygen:


shapeBiconcave disc

volumesurface area to

98

1 Adaptive features of red blood cells for carrying oxygen:

• shortens diffusion path for oxygen


shapeBiconcave disc

diffusion path

99

In air sacs, oxygen concentration is .

oxyhaemoglobin

haemoglobin

high


+ oxygen

carried by blood

2 Transport of oxygen:

100

haemoglobin

oxyhaemoglobin

lowIn body cells, oxygen concentration is .


+ oxygen

body cells

2 Transport of oxygen:

101

plasma

hydrogencarbonate ions (HCO3-)

carbon dioxide

3 Transport of carbon dioxide:


+ water

carried in

Carbon dioxide is produced by body cells.

102

watercarbon dioxide

3 Transport of carbon dioxide:


+

air sacs

hydrogencarbonate ions

When blood reaches the air sacs,

103

7.4 Ventilation

Ventilation (換氣 )

ExhalationInhalation

Breathing

involves

brought about by

104

7.4 Ventilation

InhalationAnimation

1a Intercostal muscles contract.Rib cage moves upwards and outwards.

105

7.4 Ventilation

Inhalation

1b Diaphragm muscles contract.Diaphragm flattens.

106

7.4 Ventilation

Inhalation

2 Volume of thoracic cavity increases, pressure decreases.

107

7.4 Ventilation

Inhalation

3b Air pressure in the lungs is lower than atmospheric pressure.

3a Lungs expand.

108

7.4 Ventilation

Inhalation

4 Air rushes into lungs.

air

109

7.4 Ventilation

Ventilation (換氣 )

ExhalationInhalation

Breathing

involves

brought about by

110

7.4 Ventilation

Exhalation

1a Intercostal muscles relax.Rib cage moves downwards and inwards.

111

7.4 Ventilation

Exhalation

1b Diaphragm muscles relax.Diaphragm returns to dome shape.

112

7.4 Ventilation

Exhalation

2 Volume of thoracic cavity decreases, pressure increases.

113

7.4 Ventilation

Exhalation

3b Air pressure in the lungs is higher than atmospheric pressure.

3a Lungs recoil.

114

7.4 Ventilation

Exhalation air

4 Air is forced out of the lungs.

115

7.4 Ventilation

air pressure in thoracic cavity

time

atmospheric pressure

exhalation inhalation exhalation inhalation

116

respiration = breathing = ventilation

7.4 Ventilation

117

Respiration :

The chemical process of releasing energy from food.

7.4 Ventilation

118

Breathing :

The mechanical process of moving air into and out of the breathing system.

7.4 Ventilation

119

Ventilation :

The movement of air over the respiratory surface to faciliate gas exchange.

7.4 Ventilation

120

7.4 Ventilation

What is the difference in composition between

inhaled and exhaled air?

121

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

122

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

123

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

124

7.4

7.4 Ventilation

Results and discussion

The results show that exhaled air contains less oxygen but more carbon dioxide than inhaled air.

125

Oxygen7.4 Ventilation

Inhaled air

Exhaled air

Why different / the same?

21%

16%

Used by body cells for respiration

126

Carbon dioxide7.4 Ventilation

Inhaled air

Exhaled air


0.03%

4%

Produced by body cells during respiration

127

Nitrogen7.4 Ventilation

Inhaled air

Exhaled air


78%

78%

Not used or produced by body cells

128

Water vapour7.4 Ventilation

Inhaled air

Exhaled air


Variable

Saturated

Moistened by mucus and water film

129

Other gases7.4 Ventilation

Inhaled air

Exhaled air

1%

1%

130

Temperature7.4 Ventilation

Inhaled air

Exhaled air


Cooler

Warmer

Warmed by blood

131

• Inhaled air consists mainly of oxygen.

7.4 Ventilation

• Exhaled air consists mainly of carbon dioxide.

132

Both inhaled and exhaled air consists mainly of nitrogen (about 78%).

7.4 Ventilation

133

There is more carbon dioxide than oxygen in exhaled air.

CO2

O2 7.4 Ventilation

134

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

135

1 Ventilation involves and ex . It is brought about by the movements of the and the .

inhalation

diaphragm

exhalationrib cage

7.4 Ventilation

136

7.4 Ventilation

Inhalation Exhalation

Diaphragm muscles

Diaphragm

Contract Relax

Flattened Dome shape

137

7.4 Ventilation


Intercostal muscles

Rib cage

Contract Relax

Moves upwards & outwards

Moves downwards & inwards

138

7.4 Ventilation


Volume of thoracic cavity

Lungs

Increases Decreases

Inflated Deflated

139

7.4 Ventilation


Air pressure in lungs

Lower than atmospheric

pressure

Higher than atmospheric

pressure

Direction of air flow

Into the lungs

Out of the lungs

140

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

141

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.

142

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.

143

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.

144

Gas exchange

respiratory surface (air sacs)

human breathing system

are parts of

takes place at

145

Gas exchange

ventilation

breathing

brought about by

facilitated by

146

involvesbreathing

inhalation exhalation

contraction of intercostal &

diaphragm muscles

relaxation of intercostal & diaphragm muscles

brought about by

147

Gas exchange

respiratory gasesinclude

involves diffusion of

oxygen carbon dioxide

haemoglobin in red blood cells

hydrogencarbonate ions in plasma

transported by transported mainly as

think about… 7.1 the human breathing system 7.2 gas exchange in the air sacs

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