anim_pulmonary_ventilation _answer_key.doc

Pulmonary Ventilation To complete this worksheet, select: Module: Gas Exchange and pH Balance Activity: Animations Title: Pulmonary Ventilation Introduction 1. Define the following: ventilation – process of bringing air into and out of the lungs. inspiration process of moving air into the lungs. expiration –process of moving air out of the lungs 2. Describe how lung volume affects pressure and therefore air movement. As volume increases, as with inspiration, pressure decreases. When the pressure drops below atmospheric pressure, air enters the lungs and inhalation occurs. During exhalation the volume in the thoracic cavity decreases raising the pressure to a level that is greater than the atmosphere pressure and therefore air moves out of the lungs. Pressure Volume Relationships 3. Explain what happens to pressure in each of the following situations. Increasing Volume – pressure decreases. Decreasing Volume - increases pressure. Normal Inspiration 4. Describe and explain alveolar pressure change as the diaphragm flattens and the intercostals muscles contract. As the diaphragm flattens or contracts, there is an increase in alveolar pressure due to a drop in thoracic volume. The end result is air being forced out of the alveoli. 5. a. Why is expiration referred to as a “passive” process? Because there is no active contraction of muscles under normal circumstances. b. Describe and explain alveolar pressure change as the muscles relax and the lungs recoil. As the muscles relax and the lungs recoil, alveolar volume decreases and the alveolar pressure increases. This rise in pressure allows air to move out of the alveoli during expiration..