mechanisms+of+breathinggms

1. Define inspiration, expiration Inspiration - The active phase of ventilation when the diaphragm and the external intercostal muscles contract Expiration - The passive phase of breathing and no effort is required. The elastic properties of the thoracic wall and lungs cause them to recoil 2. Where are the intercostal muscles? Between the ribs 3. Where is the diaphragm muscle? 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 ribs joined to the vertebral column posteriorly and to the sternum anteriorly forms the top and sides of the thoracic cavity. The intercoastal muscles lie between the ribs Sealed off because nothing can get in and out of the cavity. 5. Describe the diaphragm and intecostal muscles during inspiration. during inspiration the diaphragm and inecostal muscles are contracting the diaphragm during inspiation becomes a flattened sheet of muscle when it contracts 6. Air does NOT force open the lungs. So why does air enter the lungs? As the lung volume increasees the air pressure within the alveoli decreases creating a partial vacuum. In other words Alveolar pressure is now less than atmosphereic pressure and air will naturally flow from outside the body into the lungs. 7. Passive Recoil occurs during expiration. What does that mean? it means you exhale air when your the elastic properties of the thoracic wall and lungs recoil and this causes the surface tnesion of the fluid lining the alveoli tends to draw them closed the rib cage moves down and inward causing air to leave the lungs 8. Why is air pushed out during expiration? the abdominal organs press up against the diaphragm and the rib cage moves down and inward 9. How can you achieve maximum inspiratory effort? increasing the size of your thoracic cavity larger than normal allowing the maximum expansion of your lungs. 10. How can you force expiration which is usually passive? the abdominal wall muscles contract and the rib cage is moved downward and inward which forces air out of the body 11. Do you use your total lung capacity when you breathe? What do you use? no you just use the tidal volume which is only about 500 mL 12. Why are the nasal cavities, trachea, bronchii, and bronchioles considered "dead air space"? These passages are not used for gas exchange and thats why they are called dead air space 13. How should you breathe to get the most fresh air to your alveoli? Why? breathe slowly and deeply so all the air can get to your lungs and not get caught in the dead air space before you breathe in again