class: name: date: 7 gas exchange in humansbio662.dyndns.info/dse/ws/ws_ch07_e.pdf · new senior...

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New Senior Secondary Mastering Biology Oxford University Press 2014 (Second Edition)

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7 Gas exchange in humans

7.1 The human breathing system (Book 1B, p. 7-3)

� Cells carry out (1) _______________ to release energy for cellular activities. To ensure the

supply of (2) _______________ to cells and the removal of (3) _______________

_______________ from cells, gas exchange (氣體交換) takes place continuously between the

cells and the external environment.

� In humans, a (4) _______________ _______________ (呼吸系統) is developed for efficient

gas exchange. A (5) _______________ _______________ (運送系統) is also developed to

carry gases between the sites of gas exchange and other body cells.

� The human breathing system consists of the (6) _______________ ______________ (呼吸道)

and structures that aid breathing.

(7) _______________

(鼻孔)

(8) _______________

(小支氣管)

intercostal muscle (肋間肌)

(9) _______________

(肋骨)

air sac (氣囊)

inner pleural membrane

(內胸膜)

outer pleural membrane (外胸膜)

pleural cavity (胸膜腔)

nasal cavity (鼻腔)

pharynx (咽)

(10) _______________

(會厭)

(11) _______________

(喉)

(12) _______________

(氣管)

(13) _______________

(支氣管)

lung (肺)

diaphragm (橫膈膜)

▲ The human breathing system


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Structure Feature

Nostril � With (14) _______________ to filter larger dust particles from the air

Nasal

cavity

� Lined with mucus-secreting cells which secrete (15) ______________ (黏液)

to trap dust particles and bacteria, and moisten the incoming air

� Lined with ciliated epithelial cells (纖毛上皮細胞) which have

(16) _______________ (纖毛) to sweep the mucus towards pharynx

� Lined with capillaries which carry blood to warm up the incoming air

Pharynx � Where the respiratory tract and the alimentary canal meet

Epiglottis � Covers the opening of larynx during (17) _____________ to prevent choking

Larynx � Mainly made of (18) _______________

� Contains vocal cords (聲帶) which vibrate to produce sound

Trachea � Supported by (19) _______________ cartilages

� Lined with mucus-secreting cells, ciliated epithelial cells and capillaries

Bronchus � Supported by circular rings of cartilages

� Lined with mucus-secreting cells, ciliated epithelial cells and capillaries

Lung � Mainly composed of bronchioles and air sacs

Bronchiole � No cartilage

� Larger ones lined with mucus-secreting cells and ciliated epithelial cells

Air sac � Provides a large respiratory surface (呼吸表面)

� Surrounded by a network of (20) _______________

Rib � Makes up the rib cage (肋骨籃) with (21) _______________ (胸骨) and

vertebral column (脊柱) to protect the lungs

Intercostal

muscle

� Located between each pair of ribs

� Involved in breathing

Pleural

membranes

� Enclose the lungs

� Secrete (22) _______________ _______________ (胸膜液)

Pleural

cavity

� Contains pleural fluid which acts as a (23) _______________ to reduce

friction during breathing movement

Diaphragm � A sheet of muscle lying at the bottom of the rib cage

� Involved in breathing


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� The path of air flowing through the respiratory tract into the lungs:

Nasal cavity → (24) _______________ → larynx → (25) _______________ → bronchus

→ bronchiole (in lungs) → (26) _______________ _______________ (in lungs)

� Go to

Practical 7.1 Examination of the mammalian breathing system

(Book 1B, p. 7-4; Practical Workbook for SBA 1B, p. 7-1)

Practical 7.2 Examination of pig lungs


7.2 Gas exchange in the air sacs (Book 1B, p. 7-10)

A How does gas exchange take place? (Book 1B, p. 7-10)

blood from pulmonary artery

blood to pulmonary veins

epithelium (one-cell thick)

water film

oxygen

carbon dioxide red blood cell

Uptake of oxygen by the blood Removal of carbon dioxide into the air sacs

1 Inhaled air flows into the air sacs.

2 Oxygen in the inhaled air

(1) _______________ in the water film

lining the air sacs.

3 Since the oxygen concentration in the water

film is (2) _______________ (lower /

higher) than that in the blood, oxygen

(3) ______________ across the walls of the

air sacs and the capillaries into the blood.

1 Since the carbon dioxide concentration in

the blood is (4) _______________ (lower

/ higher) than that in the water film lining

the air sacs, carbon dioxide diffuses

across the walls of the capillaries and the

air sacs into the air in the air sacs.

2 Carbon dioxide is removed from the body

when we exhale.


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B What are the adaptive features of air sacs for gas exchange? (Book 1B, p. 7-11)

Feature Adaptation

Large in number Provides a very large (5) _______________

_______________ for the diffusion of gases

Thin walls ((6) _______________ thick) Reduces the diffusion distance

(7) _______________ inner surface Allows gases to dissolve before diffusing across

the walls of the air sacs

Richly supplied with capillaries Allows rapid transport of gases, which helps

maintain a steep (8) _______________ gradient

of gases between the air sacs and the blood

Lying close to the capillaries Reduces the diffusion (9) _______________

C What is the difference in composition between inhaled air and

exhaled air? (Book 1B, p. 7-12)

Inhaled air

Exhaled air

Reason for the difference

Oxygen 21% 16%

Oxygen in inhaled air diffuses from the air sacs

into the blood during gas exchange. It is then

used by the body cells for (10) _____________.

Carbon dioxide 0.03% 4%

Carbon dioxide produced by body cells during

respiration diffuses from the blood into the air

sacs during gas exchange.

(11) ______________ 78% 78% It is not used or produced by body cells.

Water vapour Variable Saturated

Air is moistened by the (12) _______________

lining the respiratory tract and the water film

lining the air sacs.

Other gases 1% 1% They are not used or produced by body cells.

� Exhaled air is warmer than inhaled air because exhaled air is warmed by the blood in the

(13) _______________.


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� Go to

Practical 7.3 Examination of mammalian air sacs


Practical 7.4 Comparison of the oxygen content of inhaled air and exhaled air


Practical 7.5 Comparison of the carbon dioxide content of inhaled air and exhaled air


7.3 Transport of respiratory gases (Book 1B, p. 7-16)

A How is oxygen transported? (Book 1B, p. 7-16)

� Oxygen is mainly transported by (1) ______________ _______________ _______________

in the blood.

▲ Computer artwork of red blood cells

� Adaptive features of red blood cells for carrying oxygen:

Feature Adaptation

I Fully packed with

haemoglobin (血紅蛋白)

a Provides a short distance for oxygen to reach and

leave the haemoglobin in the red blood cells rapidly

b Provides more room for holding haemoglobin II Biconcave disc shape

(雙凹圓盤狀)

III No nucleus when mature

c Provides a large surface area to volume ratio for

the diffusion of oxygen

d Allows the red blood cells to carry a large amount of

oxygen

I: (2) ____________ II: (3) ____________ & (4) ____________ III: (5) ___________


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Uptake of oxygen from air sacs

inhaled air

oxygen

air sac

haemoglobin + oxygen oxyhaemoglobin

capillary

red blood cell blood flow direction

1 The oxygen concentration in the air sacs is (6) _______________ (low / high) due to the

continuous replacement of air from the external environment.

2 Oxygen in the air sacs diffuses into red blood cells.

3 Oxygen combines with haemoglobin to form (7) _______________ (氧合血紅蛋白), which

gives the blood a bright red colour.

haemoglobin + oxygen → oxyhaemoglobin

4 The red blood cells containing oxyhaemoglobin are then carried to the body tissue.

Release of oxygen to body tissue

body cell

oxyhaemoglobin haemoglobin + oxygen

capillary

red blood cell

blood flow direction

1 The oxygen concentration in the body tissue is (8) _______________ (low / high) because

the body cells in the tissue consume oxygen for respiration.

2 Oxyhaemoglobin in the red blood cells breaks down into haemoglobin and oxygen.

oxyhaemoglobin → haemoglobin + oxygen

3 The oxygen diffuses into the body cells and the blood becomes purplish red.


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B How is carbon dioxide transported? (Book 1B, p. 7-18)

Uptake of carbon dioxide from body tissue

body cell

CO2 + H2O H+ + HCO3

–

capillary

red blood cell blood flow direction

enzyme

plasma

HCO3–

1 The carbon dioxide concentration in the body tissue is (9) _______________ (low / high)

because carbon dioxide is continuously produced by body cells through respiration.

2 Most carbon dioxide diffuses into red blood cells and reacts with (10) _______________

to form (11) _______________ _______________ (碳酸氫鹽離子).

carbon dioxide + water hydrogen ion (H

+) + hydrogencarbonate ion (HCO3

–)

enzyme

3 The hydrogencarbonate ions diffuse out of the red blood cells and are carried by the

(12) _______________ to the air sacs.

Release of carbon dioxide to air sacs

exhaled

CO2

air sac

capillary

red blood cell

blood flow direction

enzyme

plasma

HCO3– HCO3

– +

H

+

CO2 + H2O

1 The carbon dioxide concentration in the air sacs is (13) _______________ (low / high)

because carbon dioxide is continuously removed through exhalation.

2 Hydrogencarbonate ions in the plasma enter the red blood cells and break down into carbon

dioxide and water.

hydrogen ion (H

+) + hydrogencarbonate ion (HCO3

–) carbon dioxide + water

enzyme

3 The carbon dioxide diffuses into the plasma and then into the air sacs, and is finally exhaled.


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7.4 Ventilation (Book 1B, p. 7-20)

� Ventilation (換氣) is necessary to bring fresh air to the lungs to maintain a high

(1) _______________ content in the air sacs and to remove (2) _______________

_______________ from the lungs.

� It includes (3) _______________ (吸氣) and (4) _______________ (呼氣).

� Mechanism of inhalation and exhalation:

Inhalation Exhalation

air flow

movement

of rib cage

movement of diaphragm

air flow

movement

of rib cage

movement of diaphragm

Intercostal muscles (5) _______________

(Contract / Relax)

(13) _______________

(Contract / Relax)

Rib cage Moves (6) _______________

(upwards / downwards) and

(7) _______________

(inwards / outwards)

Moves (14) _______________

(upwards / downwards) and

(15) _______________

(inwards / outwards)

Diaphragm

muscles

(8) _______________

(Contract / Relax)

(16) _______________

(Contract / Relax)

Diaphragm (9) _______________ (Recoils to

dome shape / Flattens)

(17) _______________ (Recoils

to dome shape / Flattens)

Volume of thoracic

cavity

(10) _______________

(Increases / Decreases)

(18) _______________


Volume of lungs (11) _______________


(19) _______________


Air pressure in the

lungs

Becomes (12) _______________

(lower / higher) than the

atmospheric pressure

Becomes (20) _______________

(lower / higher) than the


Air flow Into the lungs Out of the lungs


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� The volume of lungs and the air pressure in the lungs change periodically as we breathe.

� The change in volume of lungs during inhalation and exhalation:

volume of lungs

time (s) 0 2 4 6

(21) _______________ (inhalation / exhalation)


� The change in air pressure in the lungs during inhalation and exhalation:

air pressure in lungs

time (s) 0 2 4 6





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� A (25) _______________ model can be used to illustrate the movement of the ribs during

inhalation and exhalation.

� In the model, the vertical rods represent the vertebral column and the (26) _______________.

The horizontal rods represent the (27) _______________. The rubber band represents the

(28) _______________ _______________.


1 Intercostal muscles contract.

2 Ribs move upwards and outwards.

3 Volumes of the

thoracic cavity

and lungs

increase.

1 Intercostal

muscles relax.

2 Ribs move downwards and inwards.

3 Volumes of the

thoracic cavity

and lungs

decrease.

� A (29) _______________ model can be used to show how the movement of the diaphragm

brings about inhalation and exhalation.

� In the model, the rubber sheet represents the (30) _______________. The wall of the bell jar

represents the (31) _______________ _______________. The balloons represent the

(32) _______________.


1 Diaphragm is pulled down.

4 Air rushes into the lungs.

3 Volume of the

lungs increases.

2 Volume of the

thoracic cavity

increases. The

air pressure

inside decreases.

1 Diaphragm is

pushed upwards.

4 Air is forced out.

3 Volume of the

lungs decreases.

2 Volume of the

thoracic cavity

decreases. The

air pressure

inside increases.


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Answers

Ch 7 Gas exchange in humans

7.1 1 respiration 2 oxygen 3 carbon dioxide 4 breathing system 5 transport system

6 respiratory tract 7 nostril 8 bronchiole 9 rib 10 epiglottis

11 larynx 12 trachea 13 bronchus 14 hairs 15 mucus

16 cilia 17 swallowing 18 cartilage 19 C-shaped 20 capillaries

21 sternum 22 pleural fluid 23 lubricant 24 pharynx 25 trachea

26 air sac

7.2 1 dissolves 2 higher 3 diffuses 4 higher 5 surface area

6 one-cell 7 Moist 8 concentration 9 distance 10 respiration

11 Nitrogen 12 mucus 13 capillaries

7.3 1 red blood cells 2 d 3 a / c 4 c / a 5 b

6 high 7 oxyhaemoglobin 8 low 9 high 10 water

11 hydrogencarbonate ions 12 plasma 13 low

7.4 1 oxygen 2 carbon dioxide 3 inhalation 4 exhalation 5 Contract

6 upwards 7 outwards 8 Contract 9 Flattens 10 Increases

11 Increases 12 lower 13 Relax 14 downwards 15 inwards

16 Relax 17 Recoils to dome shape 18 Decreases 19 Decreases

20 higher 21 inhalation 22 exhalation 23 inhalation 24 exhalation

25 rib-cage 26 sternum 27 ribs 28 intercostal muscles

29 bell-jar 30 diaphragm 31 thoracic wall 32 lungs

class: name: date: 7 gas exchange in humansbio662.dyndns.info/dse/ws/ws_ch07_e.pdf · new senior...

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