Unit 8 - H Gas Exchange

AS LEVEL
B I O LO GY

,9 Gas exchange and smoking ................................3

9.1 The gas exchange system .............................................3
Lungs ..........................................................................3
Trachea, bronchi and bronchioles .................................3

Alveoli ........................................................................5
Gas exchange .............................................................6
9.2 Smoking .....................................................................7
Smoking......................................................................8

Tobacco smoke ............................................................8
Lung diseases ..............................................................9
Short-term effects on cardiovascular system .................12

, 9 GAS EXC HANGE A
SMOKING
The gas exchange system is responsible for the uptake of oxygen into the b
excreting carbon dioxide. An understanding of this system shows how cells,
organs function together to exchange these gases between the blood and t
environment. The health of this system and of the cardiovascular system is p
smoking.


Candidates will be expected to use the knowledge gained in this section to
in familiar and unfamiliar contexts.



9 .1 T H E G A S E X C H A N G
SYSTEM
The gas exchange surface in the lungs is extensive, very thin, well supplied
well ventilated. The trachea and bronchi provide little resistance to the mov
and from the alveoli.


LEARNING OUTCOMES

C ANDIDATES SHOULD BE ABLE TO:

A. describe the gross structure of the human gas exchange system


Lungs

- Lungs are in thoracic (chest) cavity surrounded by pleural membranes, wh
airtight space; this space contains small quantity of fluid to allow friction-

as lungs are ventilated by movement of diaphragm and ribs.