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Breathing and Gas Exchange

Things you must know

Describe the structure of the thorax, including the:
intercostal muscles,
alveoli and
pleural membranes

understand the role of the intercostal muscles and the diaphragm, in ventilation

Explain how alveoli are adapted for gas exchange by diffusion…

Page 2

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The deepness of each breath (the deeper the breath, the greater the volume of air moved
per breath).

Anatomy of Lungs

Key structures

Ribs, intercostal muscles, diaphragm, lungs.
Trachea (windpipe), Bronchus (bronchi), Bronchioles, alveolus (alveoli)
Pleural membranes, pleural cavity.

The zone of the body between the neck and the bottom…

Page 3

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Two tubes that are each known as a bronchus, plural bronchi ­ carry air into the
bronchioles within the lungs.

Bronchioles which are subdivisions of each bronchus.

Alveoli which are sacs at the end of the airways, the sites of gas exchange.

Pleural membranes ­ attached to inside wall of…

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A very large surface area (the inside of each is folded to increase its surface
area) which speeds up diffusion of gases.

Rich blood capillary network for rapid gas exchange

The inside surface is moist so that the gases dissolve . They can then diffuse
across the membrane.

Oxygen/ Carbon…

Page 5

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Investigation to show how the rate of exercise affects breathing rate

Key Variables to Control

Same subjects for each exercise regime then take an average
same age
same sex
same level of fitness
same food intake

Or you could use a range of subjects BUT THEN they must all do…




This set of notes contains useful information on what you need to know, and clear explanations of the mechanism of breathing and gas exchange. Adding a line to the diagram  to show the position of the diaphragm at rest and when breathing in would be useful as this can be asked in questions.

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