Breathing+AG

Allie Gruber Human Bio Field Period 1 September 30, 2008

Mechanism of Breathing pp. 174-176

1. Define inspiration, expiration. Inspiration moves air into the lungs while expiration moves the air out.

2. Where are the intercostal muscles? Intercostal muscles lie between the ribs.

3. Where is the diaphragm muscle? The diaphragm and connective tissues form the floor of the thoracic cavity.

4. The lungs are in a "sealed" off thoracic cavity. Describe this cavity. Why is it considered "sealed"? The cavity is made up of the lungs and is sealed off by the rib cage consisting of ribs joined to the vertebral column and sternum.

5. Describe the diaphragm and intecostal muscles during inspiration. In inspiration the diaphragm and the external intercostal muscles contract. The diaphragm changes from a dome-shaped object as well as a flattened sheet of muscle while contracted. The external intercostal muscles contract and the rib cage moves upward and outward.

6. Air does NOT force open the lungs. So why does air enter the lungs? As the lung volume increases, the air pressure within the alveoli decreases, creating a partial vacuum and allowing a continuous column of air to rach the lungs from the outside of the body.

7. Passive Recoil occurs during expiration. What does that mean? The recoil is caused by the elastic properties of the thoracic wall and lungs. They do this because the surface tension of the fluid lining the alveoli tends to draw them closed. The abdominal organs press up against the diaphragm and the rib cage moves down and inward.

8. Why is air pushed out during expiration? The thoracic cavity and lungs resume their original positions and pressures, forcing the air out.

9. How can you achieve maximum inspiratory effort? This involves muscles of the back, chest and neck, which increase the size of the thoracic cavity larger than normal allowing maximum expansions of the lung.

10. How can you force expiration, which is usually passive? Forced expiration accompanies the maximum isnspiratory efforts of heavy exercise.

11. Do you use your total lung capacity when you breathe? What do you use? When relaxed, the total lung capacity is not reached, but the vital capacity is what is used to increase the amount of air inhaled and exhaled.

12. Why are the nasal cavities, trachea, bronchii, and bronchioles considered "dead air space"? They are “dead air space” because they are not used for gas exchange.

13. How should you breathe to get the freshest air to your alveoli? Why? Breathing slowly and deeply to ensure the air remains in the lungs and are not used for gas exchange.