Gaseous Exchange

1. GRADE 11: LIFE
SCIENCES
STRAND 2: LIFE
PROCESSES IN PLANTS
AND ANIMALS

2. TOPIC 2.4
GASEOUS EXCHANGE
The Structure of the Gaseous Exchange System
of Humans

3. THE AIR PASSAGE
THE AIR PASSAGE CONSISTS OF THE NOSTRILS, NASAL PASSAGE, THE
TRACHEA, BRONCHI AND BRONCHIOLES
The nostril and nasal passage
• Two nostril leads to the nasal cavity
• The hair in the nostril remove dust in the inhaled air
• The vertical septum separates the two nasal cavities
• Further divided by three turbinate bones into three passages
• Lined by ciliated columnar epithelial cells with goblet cells
• Air slowed down by turbinate bones and is warmed, moistened and cleared from
dust and germs trapped in the mucus as it passes in nasal passages

4. THE
NOSTRIL
AND NASAL
PASSAGE

5. The trachea
• Air move from the nasal passage to the pharynx
• (pharynx also play a role in digestive system. It also leads lead to the oesophagus.
When swallowing food, the glottis is closed by leaf-like cartilage called the
epiglottis)
• Pharynx leads to the trachea on an opening called glottis
• Upper part of the trachea is the larynx or voice box
• Trachea is the long tube made strong by the C-ring-shaped cartilages
• Keeps the trachea open always

6. The trachea

7. The bronchi and bronchioles
• Trachea divides, forming two bronchi in the chest cavity
• Each bronchi is adapted with the same structure as the trachea
• Each bronchi goes into one lung dividedly into smaller units of bronchioles
• Smaller bronchioles have no cartilage
• The end branch of each small bronchioles are called alveoli

8. The bronchi and bronchioles

9. THE HUMAN LUNGS
External structure
• The appearance of the lungs is spongy
• Has a diaphragm muscle at each end
• Diaphragm is thin sheet-like muscle separating the thoracic and abdominal cavity
• Intercostal muscle (set of breathing muscles) are located between the rib cages that protects the lungs
• Hilum – the concave side of each lung
• Pulmonary arteries and veins enters and leave the lungs respectively at the hilum
• Bronchi also enters the lungs at the hilum
• Left lung – 2 lobes and right lung – 3 lobes
• Pleura – covers the external part of the lung and inside of the thoracic cavity
• Layers of Pleura has fluid that reduce friction during breathing movements

10. Internal structure
• Bronchi divides to smaller units forming bronchioles
• Smaller bronchioles do not have cartilaginous rings
• The end point of bronchioles are called alveoli (air sacs)
• Alveoli walls are made up of squamous epithelial cells
• Pulmonary artery breaks into arterioles to give rise to capillaries in the
walls of alveoli
• Capillaries form venules that form pulmonary veins that leave the lungs
and enter the heart

11. HUMAN LUNGS

13. REFERENCES
• https://www.slideshare.net/poiuytrew21/grade-8-respiratory-system?qid=fa9e12c1-
b133-4849-bac7-e538e8c5d994&v=&b=&from_search=4 [accessed on 19 August 2020]
• https://www.slideshare.net/MohanadAljashamy/trachea-55877756?qid=e691e96f-259f-
4c57-9e6f-c33a696a4115&v=&b=&from_search=2 [accessed on 19 August 2020]
• https://www.slideshare.net/alsafer89/bronchial-tree?qid=ff096f13-ab0f-4d7d-b356-
e6ef854e20ba&v=&b=&from_search=8 [accessed on 19 August 2020]
• https://www.slideshare.net/maswazi10/unit-3-respiratory-system-and-gas-exchange
[accessed on 19 August 2020]
• Articles:
https://www.researchgate.net/search?context=publicSearchHeader&q=respiratory+syste
m+bronchioles [accessed on 19 August 2020]