# Ventilation Mechanic II Flashcards Preview

## Human Physiology > Ventilation Mechanic II > Flashcards

Flashcards in Ventilation Mechanic II Deck (12)
0
Q

FEV1 Forced expiratory capacity

A

Volume of force exhale after 1 sec.

- fx of lung size, elasticity and airway diameter (resistance)

1
Q

FVC Forced Vital Capacity

A

Max forced exhale that starts after a inhaling max amnt (volume) of air.
- generally VC (vital capacity) > FVC

2
Q

FEV (forced expiratory volume)/FVC (forced vital capacity) ratio is higher or lower in Obstructed Pulm dz?

A

ratio (%) is lower (airway is clogged with mucus debris): can’t move air very fast (and in addition, amount/volume of air out is smaller than that of a normal person)

3
Q

In restrictive pulm dz the FEV/FVC ratio is higher or lower?

A

its normal: moves air very quickly but smaller amount of air than normal person

4
Q

Does change in diameter of airway affect FVC the same way it affect FEV1?

A

No, change in diameter doesn’t affect FVC (total forced expired volume):
when d is decreased, FEV1 (forced expired volume per minute) is decreased more (but total volume expired (FVC) is not decreased - it just takes it longer to get out??)

Both are affected by lung size and elasticity

5
Q
```Surface Tention (ST or T) is interaction of H2O molecules that tends to collapse the lung
Surfactant```
A

dicreases the intermolecular forces between H20 molecules and decreases ST

6
Q

Compliance is

A

delta V/delta P
As volume increases, C decreases
high C= easy to inflate lungs
When pressure around lung is decreased, lung inflates/expands

7
Q

Lung have high C (distensible):
large volume change per unit pressure change

Recoil (collapsing) forces of lung are due to

A
• alveolar ST
• elastic fibers in lung (collagen and elastin)
• increase STa or elastic fibers = DECREASE C
8
Q

What decreases lung C?

A
• high lung volume (as volume increases, C decreases)
• pulm fibrosis (restrictive lung dz due to decreased lung+/- wall expansion)
• pulm congestion (blood)
• surfactant deficiency
• edema (in IF or in alveoli itself)

Increase surfactant = decrease ST (bc breaks down H2O) = Increase C?

9
Q

What increases lung compliance?

A
• lower lung volumes
• emphysema (loss of elastic lung elements)
• age increase (loss of elastic tissues)
10
Q

Why does compliance increase in emphysema (obstructive)?

A

elastic fibers destroyed by protease and elastases

11
Q

Why does compliance decrease in restrictive lung disease?

A

fibrotic tissue in parenchyma of lung makes expansion more difficult