Respiratory Physiology: Mechanics of Breathing Flashcards
1
Q
- Define minute ventilation
A
The minute volume of respiration or the Total volume of air taken in during one minute
2
Q
Define alveolar ventilation
A
the volume of air that reaches the respiratory zone
3
Q
- How does Gas flow in terms of pressure
A
gas flows from higher to lower pressures
4
Q
- What allows for the volume of the thorax to increase so the air inside it is under less pressure?
A
Muscular movement
5
Q
What is quiet inspiration called?
A
Eupnea
6
Q
What percentage of quiet inspiration is movement of the diaphragm and how does the diaphragm contract
A
75%
7
Q
- What percentage of quiet inspiration is movement of the external intercostal muscles and what does it contract for?
A
25%
8
Q
what nerves cause the diaphragm to contract?
A
Phrenic nerves
9
Q
- Outline the mechanism for quiet expiration
A
- Inspiratory muscles relax
- Rib cage drops under force of gravity
- Relaxing diaphragm moves superiorly (up)
- Thorax and lungs decrease volume simultaneously
- thus, pressure increases
- Air is forced out
10
Q
- How much does the diaphragm lower in forced inspiration and how much air enters the lungs as a result
A
lowers about 10cm
11
Q
- What do sternocleomastoids do in forced inspiration
A
elevate the sternum
12
Q
- What do scalenes do in forced inspiration
A
elevate the first two ribs
13
Q
- What does the pectoralis minor do in forced inspiration
A
elevates the third to fifth ribs
14
Q
- Outline the mechanism for forced expiration
A
- Internal intercostal muscles and latissimus dorsi depresse the rib cage, decreasing the thoracic volume
- Oblique and transversus abdominis cause the contraction of abdominal wall muscles
- Intra-abdominal pressure is increased to force the diaphragm superiorly and air out
15
Q
- What does alveolar pressure decrease to in normal quiet inspiration
A
758 mm Hg
