Ventilation

Question 1

What two things are affected by compliance during inspiration?

Answer 1

1. Inflation of chest cavity
2. Inflation of lung

Question 2

What is affected by airway resistance during inspiration?

Answer 2

Inward air-flow

Question 3

What is minute ventilation (V_E) and how is it calculated?

Answer 3

V_{<strong>E:</strong>} Volume of air-flow through the lung in one minute

• Tidal volume (TV) x Breathing rate

Question 4

What is alveolar ventilation V_A?

Answer 4

Volume of airflow in alveolar space in one minute

Question 5

What factors affect V_A?

Answer 5

• Obstructive disease (e.g. COPD)
• Compliance problems
• Excercise (can increase ventilation 10x)
• High altitude

Question 6

1. What causes regional variations in ventilation?
2. Where is ventilation greatest- at the top or bottom?
3. What is the ratio of Vent_bottom/Vent_top

Answer 6

1. Gravity
2. Bottom
3. Vent_bottom/Vent_top = 2.5

Question 7

What two mechanical factors affect airway resistance?

Answer 7

1. Mucous (bronchitis)
2. Lung Volume
   
   • Greater tidal volume opens the airways up and decreases resistance

Question 8

1. What is dead-space?
2. What are the two types of dead-space?
3. What is the Physiologic dead-space?

Answer 8

1. Dead-space: Volume of lung that does not engage in gas exchange
2. Anatomical dead space & alveolar deadspace
   
   • There is no gas exchange in the airways i.e. anatomical
   • Any alveoli that isnt exachanging gas with a capillary due to disease or otherwise
3. Anatomical +alveolar deadspace

Question 9

What is the effect of deadspace on the work involved in breathing?

Answer 9

• Increases the work involved in breathing
  
  • Deadspace reduces the efficiency of breathing since there is more wasted breathing.
  • e.g. - if you breath through a snorkel, it is harder to breath b/c you add deadspace to your system
  • Also effects your V/Q