1

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

3

4 The answer is…

5 …still a mystery.

6 Which parts of our 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 forms are oxygen and carbon dioxide carried around our body 3

9 7.1 The human breathing system O2O2 CO 2 gas exchange ( 氣體交換 )

10 diffuses across cell membrane 7.1 The human breathing system In very small organisms: O2O2 CO 2

The human breathing system In larger organisms: cannot diffuse across body surface O2O2 CO 2  

12 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

13 What does the human breathing system consist of? 7.1 The human breathing system

The human breathing system Human breathing system pharynx larynx trachea bronchus lung air sac bronchiole epiglottis nostril nasal cavity 3D Model

15 rib diaphragm 7.1 The human breathing system Human breathing system

The human breathing system Human breathing system intercostal muscle inner pleural membrane outer pleural membrane pleural cavity

The human breathing system air How does air flow into the lungs?

The human breathing system nasal cavity pharynx larynx trachea air

The human breathing system 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 The human breathing system 2Identify the various structures.

The human breathing system 1 Nostrils and nasal cavity i) Hairs filter larger dust particles

The human breathing system 1 Nostrils and nasal cavity ii) Mucus-secreting cells mucus traps dust particles & moistens air

The human breathing system 1 Nostrils and nasal cavity iii) Ciliated epithelial cells cilia sweep mucus with dust particles towards pharynx

The human breathing system 1 Nostrils and nasal cavity iv) Capillaries blood warms up air

25 2 Pharynx and larynx 7.1 The human breathing system larynx oesophagus trachea pharynx

26 2 Pharynx and larynx 7.1 The human breathing system larynx food oesophagus

27 2 Pharynx and larynx 7.1 The human breathing system larynx oesophagus 1 Tongue pushes food towards pharynx

28 2 Pharynx and larynx 7.1 The human breathing system larynx oesophagus 2 Soft palate moves up, preventing food from entering nasal cavity

29 2 Pharynx and larynx 7.1 The human breathing system larynx oesophagus 3 Larynx rises and epiglottis covers entrance to trachea, preventing choking

The human breathing system 2 Pharynx and larynx

The human breathing system 2 Pharynx and larynx larynx made up of cartilage epiglottis

The human breathing system 2 Pharynx and larynx vocal cords ( 聲帶 ) can vibrate to produce sound

The human breathing system trachea bronchus bronchioles 3 Trachea, bronchi and bronchioles

34 3 Trachea, bronchi and bronchioles 7.1 The human breathing system bronchus bronchioles trachea

35 3 Trachea, bronchi and bronchioles 7.1 The human breathing system C-shaped cartilage ciliated epithelial cell lumen prevents collapse

36 3 Trachea, bronchi and bronchioles 7.1 The human breathing system Trachea Bronchi Bronchiole Ciliated epithelial cells

37 3 Trachea, bronchi and bronchioles 7.1 The human breathing system Trachea Bronchi Bronchiole Mucus-secreting cells Absent in smaller bronchioles

38 3 Trachea, bronchi and bronchioles 7.1 The human breathing system Trachea Bronchi Bronchiole Capillaries

39 3 Trachea, bronchi and bronchioles 7.1 The human breathing system Trachea Bronchi Bronchiole Cartilage Absent C-shaped Circular

The human breathing system 4 Air sacs air sac large respiratory surface capillary

The human breathing system 5 Lungs in thoracic cavity ( 胸腔 ) composed of bronchioles and air sacs

The human breathing system 5 Lungs protected by rib cage ( 肋骨籃 ) ribs cartilage vertebral column ( 脊柱 ) sternum ( 胸骨 )

The human breathing system 5 Lungs intercostal muscles diaphragm sheet of muscle

The human breathing system 5 Lungs

The human breathing system 5 Lungs right lung rib intercostal muscle outer pleural membrane inner pleural membrane pleural cavity

The human breathing system 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 7.1 The human breathing system

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

Feel the hardness of the trachea and the lung tissue with a pair of forceps. 7.1 The human breathing system 4Use a water hose to fill the lungs with water through the trachea. Note the changes in the volume of the lungs. 5Draw a labelled diagram of the lungs.

50 1a The human breathing system consists of the and structures that aid breathing. respiratory tract 7.1 The human breathing system

51 air sacs bronchi larynx nasal cavity bronchioles pharynx nostrils trachea 1b Air flow along respiratory tract: 7.1 The human breathing system

52 2a In the nostrils, filter larger dust particles. 7.1 The human breathing system hairs

53 2b In the lining of nasal cavity, trachea, bronchi and bronchioles, mucus-secreting cells secrete mucus to moisten the air. mucus mucus-secreting cells 7.1 The human breathing system

54 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

55 2d In the lining of nasal cavity, trachea, bronchi and bronchioles, blood in the warms the incoming air. 7.1 The human breathing system bloodcapillaries

Gas exchange in the air sacs Respiratory gases Oxygen Carbon dioxide

Gas exchange in the air sacs Where does gas exchange take place?

Gas exchange in the air sacs in the air sacs Where does gas exchange take place?

Gas exchange in the air sacs blood flow air sac capillary Uptake of oxygen by the blood

Gas exchange in the air sacs blood flow Uptake of oxygen by the blood 1 O 2 is inhaled. O2O2

Gas exchange in the air sacs blood flow Uptake of oxygen by the blood 2 O 2 dissolves in water film. O2O2

Gas exchange in the air sacs blood flow Uptake of oxygen by the blood 3 O 2 diffuses into red blood cells. O2O2

Gas exchange in the air sacs blood flow Removal of carbon dioxide into the air sacs 1 CO 2 diffuses out from capillary. CO 2

Gas exchange in the air sacs blood flow Removal of carbon dioxide into the air sacs 2 CO 2 diffuses into air sacs. CO 2

Gas exchange in the air sacs blood flow Removal of carbon dioxide into the air sacs 3 CO 2 is exhaled. CO 2 Animation

66 Adaptive features of air sacs 7.2 Gas exchange in the air sacs 1 Large number of air sacs provide large surface area for gas exchange

67 Adaptive features of air sacs 7.2 Gas exchange in the air sacs 2 Thin wall of air sac provides short diffusion distance air sac one-cell thick epithelium

68 Adaptive features of air sacs 7.2 Gas exchange in the air sacs 3 Water film lining inner surface keeps inner surface moist to dissolve gases water film

69 Adaptive features of air sacs 7.2 Gas exchange in the air sacs 4 Network of capillaries Rapid transport of gases Maintain steep concentration gradient air sac capillary red blood cell

70 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

Identify the air sacs. air sac capillary 7.2 Gas exchange in the air sacs

Draw a labelled diagram of the air sacs. 7.2 Gas exchange in 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 7.2 Gas exchange in the air sacs

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. 1 How does gas exchange take place in the air sacs? diffuses water film 7.2 Gas exchange in the air sacs

75 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

76 Carbon dioxide in blood diffuses across the walls of the capillaries and the air sacs into the air in the air sacs. capillaries air sacs 1 How does gas exchange take place in the air sacs? 7.2 Gas exchange in the air sacs

77 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

78 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

79 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

80 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

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 7.2 Gas exchange in the air sacs

82 Oxygen in blood is transported by… 7.3 Transport of respiratory gases

83 red blood cells 7.3 Transport of respiratory gases Oxygen in blood is transported by…

84 Oxygen is mainly transported by red blood cells 7.3 Transport of respiratory gases

Transport of respiratory gases Adaptive features of red blood cells for carrying oxygen fully packed with haemoglobin ( 血紅蛋白 ) oxygen carrier

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

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 ):

Transport of respiratory gases without nucleus: Adaptive features of red blood cells for carrying oxygen more room for haemoglobin

Transport of respiratory gases Transport of oxygen In lungs In body cells O2O2 air sac red blood cell Hb + O 2 → oxyhaemoglobin

Transport of respiratory gases Transport of oxygen In lungs In body cells O2O2 oxyhaemoglobin → Hb + O 2

Transport of respiratory gases Transport of oxygen In lungs In body cells O2O2 O2O2

Transport of respiratory gases Transport of carbon dioxide In lungs In body cells CO 2

Transport of respiratory gases Transport of carbon dioxide In lungs In body cells CO 2 + H 2 O → H + + HCO 3 - hydrogencarbonate ion

Transport of respiratory gases Transport of carbon dioxide In lungs In body cells HCO 3 -

Transport of respiratory gases Transport of carbon dioxide In lungs In body cells H + + HCO 3 - → H 2 O + CO 2

Transport of respiratory gases Transport of carbon dioxide In lungs In body cells CO 2

97 increases surface area to volume ratio 1 Adaptive features of red blood cells for carrying oxygen: 7.3 Transport of respiratory gases shape Biconcave disc volume surface area to

98 1 Adaptive features of red blood cells for carrying oxygen: shortens diffusion path for oxygen 7.3 Transport of respiratory gases shape Biconcave disc diffusion path

99 In air sacs, oxygen concentration is. oxyhaemoglobin haemoglobin high 7.3 Transport of respiratory gases + oxygen carried by blood 2 Transport of oxygen:

100 haemoglobin oxyhaemoglobin low In body cells, oxygen concentration is. 7.3 Transport of respiratory gases + oxygen body cells 2 Transport of oxygen:

101 plasma hydrogencarbonate ions (HCO 3 - ) carbon dioxide 3 Transport of carbon dioxide: 7.3 Transport of respiratory gases + water carried in Carbon dioxide is produced by body cells.

102 watercarbon dioxide 3 Transport of carbon dioxide: 7.3 Transport of respiratory gases + air sacs hydrogencarbonate ions When blood reaches the air sacs,

Ventilation Ventilation ( 換氣 ) Exhalation Inhalation Breathing involves brought about by

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

Ventilation Inhalation 1bDiaphragm muscles contract. Diaphragm flattens.

Ventilation Inhalation 2Volume of thoracic cavity increases, pressure decreases.

Ventilation Inhalation 3bAir pressure in the lungs is lower than atmospheric pressure. 3aLungs expand.

Ventilation Inhalation 4Air rushes into lungs. air

Ventilation Ventilation ( 換氣 ) Exhalation Inhalation Breathing involves brought about by

Ventilation Exhalation 1aIntercostal muscles relax. Rib cage moves downwards and inwards.

Ventilation Exhalation 1bDiaphragm muscles relax. Diaphragm returns to dome shape.

Ventilation Exhalation 2Volume of thoracic cavity decreases, pressure increases.

Ventilation Exhalation 3bAir pressure in the lungs is higher than atmospheric pressure. 3aLungs recoil.

Ventilation Exhalation air 4Air is forced out of the lungs.

Ventilation air pressure in thoracic cavity time atmospheric pressure exhalationinhalationexhalationinhalation

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

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 Ventilation

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

Add 10 cm 3 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

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

125 Oxygen 7.4 Ventilation Inhaled air Exhaled air Why different / the same? 21% 16% Used by body cells for respiration

126 Carbon dioxide 7.4 Ventilation Inhaled air Exhaled air Why different / the same? 0.03% 4% Produced by body cells during respiration

127 Nitrogen 7.4 Ventilation Inhaled air Exhaled air Why different / the same? 78% Not used or produced by body cells

128 Water vapour 7.4 Ventilation Inhaled air Exhaled air Why different / the same? Variable Saturated Moistened by mucus and water film

129 Other gases 7.4 Ventilation Inhaled air Exhaled air 1%

130 Temperature 7.4 Ventilation Inhaled air Exhaled air Why different / the same? 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. CO 2 O2O2  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 exhalation rib cage 7.4 Ventilation

Ventilation InhalationExhalation Diaphragm muscles Diaphragm ContractRelax Flattened Dome shape

Ventilation InhalationExhalation Intercostal muscles Rib cage Contract Relax Moves upwards & outwards Moves downwards & inwards

Ventilation InhalationExhalation Volume of thoracic cavity Lungs IncreasesDecreases InflatedDeflated

Ventilation InhalationExhalation 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 O 2 than inhaled air. Its CO 2 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 action when 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 oxygen and 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 carbon dioxide 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 involves breathing inhalationexhalation contraction of intercostal & diaphragm muscles relaxation of intercostal & diaphragm muscles brought about by

147 Gas exchange respiratory gases include involves diffusion of oxygen carbon dioxide haemoglobin in red blood cells hydrogencarbonate ions in plasma transported bytransported mainly as