Grade 11- Gaseous Exchange

1. Gaseous Exchange
Grade 11: LIFE SCIENCES

2. INTRODUCTION
 No work is possible without a supply of energy in a useful form. Energy is needed
for the following:
 Metabolism
 For growth, repair and replacement of damaged tissues
 For movement and to keep the organism active
 To maintain a constant body temperature in mammals and birds

3. What is Gaseous Exchange?
 The diffusion of gases from an area of higher concentration to an area of lower
concentration, especially the exchange of oxygen and carbon dioxide between an
organism and its environment.
 It includes inspiration (breathing air in) and expiration (breathing air out).

4. ORGANS INVOLVED IN GASEOUS
EXCHANGE:
 TRACHEA
 EPIGLOTTIS
 BRONCHI
 BRONCHIOLES
 LUNGS- ALVEOLI

5. REQUIREMENTS FOR EFFICIENT
EXCHANGE OF GASES
 A large surface area: in relation to the body size
 Permeable: so that gases can pass through easily
 Thin walls: facilitates easy diffusion of gases
 A moist inner surface: so gases can diffuse across cell membranes
 A rich blood supply: this will provide an efficient transport system to maintain a
diffusion gradient

6. STRUCTURES IN GASEOUS
EXCHANGE: (1) THE TRACHEA
ALSO KNOWN AS THE WINDPIPE
 Lined with ciliated mucosa which is responsible for expelling mucus that is
loaded with dust and other foreign particles away from the lungs.
 It provides an air passage to the lungs for respiration.
 It is also responsible for thermoregulation. When air is cold, the trachea
helps and humidify the air entering the lungs, and vice versa.

7. TRACHEA ANATOMY

8. (2)THE EPIGLOTTIS
 A flap of cartilage found behind the tongue and in front of the larynx.
 Made of elastic cartilage covered with mucous membrane.
 Acts as a switch between the larynx and the esophagus to permit air to
enter the airway to the lungs and food to pass.
 Also protects the body from choking on food that would normally obstruct
the airway.

9. THE EPIGLOTTIS

10. (3) BRONCHI
 Formed by the division of the trachea.
 Enters the lungs at the hilus.
 Right bronchus is wider, shorter and straighter than the left.
 Bronchi subdivide into smaller and smaller branches called bronchioles.

11. (4) BRONCHIOLES
 Serve as a transition between the large cartilage and the alveoli ducts
that connect directly to the alveoli.
 The bronchioles carry oxygen-rich air into the lungs and carry carbon
dioxide rich air out of the lungs, thereby aiding in the processes of
breathing and respiration.
 The smooth muscle surrounding the bronchioles can constrict and
dilate the airway thus aiding in getting the proper amount of oxygen
into the blood.
 Terminal bronchioles end in alveoli (grape-like sacs).

12. BRONCHIOLES

13. (5) LUNGS
 Occupies most of the thoracic
cavity.
 Apex is near the clavicle.
 Each lung is divided into lobes by
fissures (left lung has 2 lobes and
the right lung has 3).

14. (6) ALVEOLI
 Tiny balloon shaped structure and
are the smallest passageway in the
respiratory system.
 To get oxygen into the blood
stream for transport to the tissues,
and to remove carbon dioxide from
the bloodstream.

15. RESPIRATORY
DISRUPTIONS/
DISEASES
 SMOKING- damages or narrows blood vessels and
influence an increased deposition of fat inside the
arteries, causing artherosclerosis.
 PNEUMONIA- alveoli fills with pus and fluid making
gas exchange difficult.
 PULMONARY FIBROSIS- fibrous connective tissue
builds up in lungs reducing their elasticity and
oxygen diffusion.
 EMPHYSEMA- alveoli burst and fuse into enlarged
air spaces causing a reduction in the surface area
for effective gas exchange.
 BRONCHITIS- airways are inflamed due to an
infection or irritant.
 ASTHMA- airways are inflamed due to irritation and
bronchioles constrict due to muscle spasms.

17. REFERENCES:
Ditshego, L. (2018). Gaseous exchange- the respiratory system. Available
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Mnyaongo, (2015). Gaseous exchange in mammals. Available from
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Khatoon, Z. (2018). Gaseous exchange in human. Available from Slideshare
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Mutilifa, S. (2012). Gaseous exchange. Available from Slideshare at:
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46c7-804f-0bf81fa7d28d&v=&b=&from_search=24 (Accessed 17 August
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University of Johannesburg. (2018). Unit 3- Respiratory System and Gas
Exchange. Available from Slideshare at :
https://www.slideshare.net/LuthandoTheophyllusN/unit-3-respiratory-system-
and-gas-exchange2?qid=0071d6ff-e5ee-46c7-804f-
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