L22: Pulmonary Ventilation & Gas Laws Flashcards
muscles for forced expiration
ab muscles
internal intercostals
define total lung capacity
max volume of gas the lungs can hold
lung capacity vs lung volume
combinations of lung volumes = lung capacity
lung volume is amount of air held in subdivisions of lungs
tidal volume
vol of air that is inspired or expired w/ each breath at rest
500 ml
inspiratory reserve volume
vol of air that can be inspired in addition to tidal vol w/ forceful inspiration
3000 ml
expiratory reserve volume
additional vol of air that can be expired at end of tidal volume by forceful expiration
1100 ml
residual volume
volume of air remaining in lungs after forceful expiration
1200 ml
vital capacity
sum of all vol that can be inspired or exhaled
4600 ml
max inspiration + max expiration
total lung capacity
vital capacity + residual vol
5800 ml
inspiratory capacity
tidal vol + inspiratory reserve vol
3500 ml
functional residual capacity
expiratory reserve vol + residual vol
2300 ml
define minute ventilation
total volume of gases moved into and out of lungs per minute
calculate minute ventilation
breaths/minute x tidal vol
= 8 L/min on average
(0.5 x breathing rate)
define alveolar ventilation
total vol of gases that enter spaces participating in gas exchange per minute
calculate alveolar ventilation
= breathing rate x (tidal vol - dead space)
=5600 ml/min on avg.
(0.35 x breathing rate)
anatomical dead spaces
trachea
bronchi
bronchioles
physiological dead space
anatomical dead space + ventilated alveoli w/ absent perfusion
total dead space in normal humans
0.15 L
what to consider when calculating dead space
ds does not participate in ventilation and contains negligible CO2
respiratory bronchioles + perfused alveoli =
0.35 L
tidal volume =
0.5 L
define pleural pressure
pressure of the fluid between parietal pleura and the visceral pleura
measured in cm of water
pleural pressure during inspiration
-5 to -7.5
pleural pressure during expiration
-7.5 to -5
define alveolar pressure
pressure of the air inside the alveoli
alveolar pressure in inspiration vs expiration
in = 0 to -1
out = 0 to +1
define transpulmonary pressure
difference between alveolar and pleural pressures
aka pressure resulting in the mvt of air in and out of lungs
define compliance of the lungs
the volume/extend to which lungs will expand for each unit increase in the transpulmonary pressure
normal compliance
200 ml of air per cm of water
compliance of the lungs is a measure of the ?
expansibility of the lungs and trachea
compliance formula
= increase in vol / increase in pressure
define elastance
measure of tendency of a hollow viscus to recoil to its normal shape after being distended and such force is removed
ex. rubber band
if surface tension was allowed in the lungs then
the alveoli would collapse
components of surfactant
phospholipids
apoproteins
Ca ions
surfactant is produced by
alveolar type II cells
surfactant function
part dissolves
the rest spreads over the surface of the water in alveoli to protect them from collapse
if air passages leading from the alveoli are blocked, then
surface tension will cause alveoli to collapse
creating positive pressure
for average alveoli, pressure =
4 cm of water
normal alveoli pressure is __, if there was no surfactant, pressure would be ?
4 cm of water
18
which is 4.5x as great
what is the major component of air
N 78%
list the 3 gas laws that relate to pulmonary function
daltons law
boyles law
henrys law
the total pressure exerted by the mixture of non-reactive gasses is equal to the sum of the partial pressure of individual gasses
daltons law
for a fixed amount of an ideal gas kept at a fixed temp, pressure and volume are inversely related
boyles law
at a constant temp, the amount of a given gas that dissolves in a given type and volume of liquid is directly related to the partial pressure of that gas in equilibrium w/ that liquid
henry’s law
gas law equation
PV = nRT
define vapor pressure
vp of water is the partial pressure exerted to escape from the liquid phase to gas phase
at normal body temp - vapor pressure =
47 mmhg
as temperature increases, vapor pressure
increases
list facts that affect rate of gas diffusion in a fluid
- solubility of gas in the fluid
- cross-sectional area of the fluid
- distance thru which the gas must diffuse
- molecular weight of the gas
- temp of fluid
