Chapter 8 Lesson 3 "How We Breathe"

Materials:

• Worksheet, "Notes over Lesson 3"
• Worksheet, "Respiration"

Objective:

• Students will identify the function and parts of the respiratory system.
• Students will describe the process of gas exchange in the lungs.
• Students will explain how the diaphragm moves when a person breathes.

Alaska Content Standards:

• SCI A-15 Students will use science to understand and describe the local environment.

Anticipatory Set: Ask the students to count the number of times they breathe in a minute. Then ask the students to imagine that they needed to get to the other side of town quickly. If they ran there as fast as they could would the number of times they breath in a minute change, why? What is the purpose of the respiratory system?

Teacher Input: As the students are breathing have them explain what is happening inside their chest? What causes their chest to expand. On Page 182 there is a picture of the respiratory system. Have the students look at a picture of the respiratory system and explain what happens when the diaphragm tightens. Then, use the terms pharynx, , larynx, larynx2, trachea, bronchi, bronchioles while looking at the pictures of each. Define those terms.

Explain the actual process of respiration use this picture for help, Use the terms: alveoli while showing this picture and define it. The alveoli are so small you need a microscope to see them. Use this picture to explain respiration. The alveoli are surrounded by capillaries. The capillaries and alveoli exchange gases through diffusion. Do any students remember what diffusion is? There is one artery in the body carrying blood high is carbon dioxide. Have students guess where it is. Help them by defining its name, pulmonary artery.

As the lungs get smaller the alveoli shrink forcing out the carbon dioxide that diffused into them. As they enlarge they fill with highly oxygenated air and the exchange of oxygen and carbon dioxide continues again. That exchange is called respiration.

Teacher Modeling:

Show the students the ADAM explanation of respiration.

Check for Understanding: Walk the students through the answers to the question on their notes worksheet.

Closure: Here is a summary of how the respiratory system works: The cells of alveoli are only one cell layer thick. Oxygen and carbon dioxide diffuse in and out, respectively, through passive diffusion. If the level of carbon dioxide in the blood becomes too high, the brain stem automatically increases the rate of breathing. The diaphragm is not the only muscle that helps in breathing. Inter costal muscles extend from the lower border of each rib to the upper border of the rib below. They assist the diaphragm.

Independent Practice: Students will complete the sheet on Respiration and take the quiz on Lesson 3, "How We Breathe"

Duration:

30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).