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Introduction to the lesson
The gas exchange system is composed of several anatomical structures which are adapted to let air into the lungs, while catching bacteria and other harmful substances before they reach the gas exchange surfaces. These structures are the trachea, the bronchi, and the bronchioles. In this lesson, we will get a general idea of the gas exchange system and focus on these structures and their role in gas exchange.
Reading
Read the section “Examining the airways” in the purple box on p.186 of your text book.
Thinking it through
- How do you respond to the information in this article?
- Why do you think it has been necessary to develop endoscopes rather than operate on the person or simply to take x-rays?
- What other endoscopes are you aware of?
- Why do you think being able to take a biopsy with the endoscope is useful?
Gas exchange and lungs
Read p.186 and study Fig. 9.2 on p.187.
Learning Activity 1
Answer the following questions in your exercise book.
- Refer to Fig. 9.2 on p.187.
- List the structures involved in the gas exchange system.
- What is the membrane called that surrounds the lung?
- Explain why the lungs have a large surface area.
- Explain why the concentration gradient in the lungs is high.
- Explain how the lungs are adapted to minimize diffusion distance.
- Bearing in mind what we learned in chapter 4 about diffusion (Fick's law), why is a large surface area, high concentration gradient and small diffusion distance is important?
- What is the only muscle in the gas exchange system?
- Why does the right lung have three lobes but the left lung only has two?
Trachea, bronchi and bronchioles
Read the section "Trachea, bronchi, and bronchioles" on p.187-189.
Learning Activity 2
Answer the following questions in your exercise book.
- Using the text and Table 9.1
- describe the trachea in terms of
- how many are found in the body
- where in the body do you find it
- approximate size
- important tissues and cells
- does it have cartilage?
- describe the bronchus in terms of
- how many are found in the body
- where in the body do you find it
- approximate size
- important tissues and cells
- does it have cartilage?
- describe the bronchioles in terms of
- how many are found in the body
- where in the body do you find it
- approximate size
- important tissues and cells
- does it have cartilage?
- describe the trachea in terms of
- Explain the purpose of the C-shaped rings of cartilage in the trachea and the irregular blocks of cartilage in the bronchi?
- Why do you think bronchioles do not have cartilage?
- Using Fig. 9.3a (p.188) and other micrographs of the trachea, draw a plan diagram of the trachea. Label your diagram.
- Using Fig. 9.3b (p.188) and other micrographs of the bronchus, draw a plan diagram of the bronchus. Label your diagram.
- Using Fig. 9.3c (p.188) and other micrographs of bronchioles, draw a plan diagram of a few bronchioles. Label your diagram.
- The airways are a particularly vulnerable part of the body. Describe how the body ensures protection of the airways from pathogens.
Definitions and review
Definitions
- Gas exchange surface
- Alveoli
- Trachea
- Bronchi
- Bronchioles
- Cartilage
- Mucus
- Goblet cells
- Macrophages
Mindmap
Start a new mindmap for chapter nine and add this section to it.