Pulmonary Ventilation and Gas Laws Flashcards
What are the inspiratory muscles
- respiratory diaphragm
- external intercostal muscles
- sternomastoids
- serratus anterior muscles
- scalene muscles
What are the expiratory muscles?
Passive at rest
FORCEFUL muscles:
-abdominal muscles
-internal intercostals
Define total lung capacity
maximum volume of gas that the lungs can hold
Describe how volumes and capacities are related
combinations of lung volumes for lung capacities
Define tidal volume; what is the value?
volume of air that is inspired or expired with each breath at rest
500 ml
Define inspiratory reserve volume; what is the value?
Volume of air that can be inspired in addition to tidal volume with forceful inspiration
3000 ml
Define expiratory reserve volume; what is the value
the additional volume of air that can be expired at the end fo tidal volume by forceful expiration
1100 ml
Define residual volume; what is the value?
volume of air that is remaining in the lungs after forceful expiration 1200 ml
What are the 4 types of pulmonary volumes?
tidal volume
Expiratory reserve value
inspiratory reserve volume
residual volume
What are the 4 pulmonary capacities?
- vital capacity
- total lung capacity
- inspiratory capacity
- functional residual capacity
Define vital capacity
The sum of all of the volumes that can be inspired or exhaled
inspiration to the max extent plus expiration to the maximum extent
4600 ml
Define total lung capacity
the sum of all of the volumes
vital capacity+residual volume
5800 ml
Define inspiratory capacity
the sum of the volumes above resting capacity= tidal volume +IRV
3500 ml
Define functional residual capacity
the sum of the volumes below the resting capacity= ERV+ RV
2300 ml
Define minute ventilation
the total volume of gases moved into or out of the lungs per minute= minute ventilation
How is minute ventilation calculated?
breaths per minute X tidal volume
16 breaths a minute x 500 mL breaths
8000 ml/min
Define alveolar ventilation
total volume of gases that enter the spaces participating in gas exchange per minute
How is alveolar ventilation calculated?
breaths per minute x (tidal volume- dead space)
16 breaths per minute x (500 ml/breath - 150 ml/breath)
=5600 ml/min or 5.6L/min
What is the anatomic dead space?
trachea, bronchi, bronchioles
What is the physiological dead space?
anatomical dead space + ventilated alveoli with poor or absent perfusion
What is the total dead space in a normal individual?
.15 L
Describe the observations in calculating dead space and describe the equation that is used
Dead space does not participate in gas exchange and has negligible CO2
CO2 in lungs equals the arterial blood
VD = VTot X (PaCO2 ─ PECO2)/PaCO2
PaCO2 is the amount of CO2 in the arterial blood
PeCO2 is the amount of CO2 in the expired air
Define pleural pressure
pressure of the fluid between parietal pleura and the visceral pleura
Define alveolar pressure
pressure of the air inside the alveoli
Define trans pulmonary pressure
difference between the alveolar pressure and the pleural pressure during any point of the inspiration or expiration cycles
Is the alveolar pressure high with inspiration or expiration?
Higher with expiration
Is the pleural pressure higher with inspiration or expiration?
higher with expiration
Define compliance
the extent to which the lungs will expand for each unit increase in the transpulmonary pressure
expressed in liters per centimeter of water
measure of expansibility of the lungs and trachea
also known as capacitance
Describe how compliance and elastane differ
compliance the the measure of ease at which a hollow viscus may be distended
elastane is the measure of the tendency of a hollow viscus to recoil toward its original dimensions
Describe surface tension and state why this would be hazardous in the lungs
When water forms a surface with air, the water molecules on the surface have a strong attraction to each other; and they attempt to contract
If this happened in the lungs, the alveoli would try to collapse creating a positive pressure in the alveoli
What are the most important components of surfactant?
- dipalmitoylphosphatidylcholine
- surfactant apoproteins
- calcium ions
Where is surfactant produced?
type 2 alveolar cells
What happens to the pressure in the alveoli if there is no surfactant
If there is no surfactant, the pressure would be about 18 cm of water pressure compared to the normal 4, which is about 4.5x as great
Describe the components of air in the atmospheric pressure and give the percentages of each component
N-78.09%
O2- 20.95%
CO2- 0.03%
What are the percentages of the components of air that are within the alveoli which is saturated with 6/18% water vapor?
N- 73.26%
02- 19.65%
Ar- 0.87%
CO2- 0.03%
Define Dalton’s law
the total pressure exerted by the mixture of non-reactive gasses is equal to the sum of the partial pressure of individual gasses
Define Boyle’s law
For a fixed amount of an ideal gas kept at a fixed temperature, P and V are inversely proportional
Define henry’s law
At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid
What is the ideal gas law
P=nRT/V
What are the partial pressures of O2 and CO2 at the alveolar membrane?
O2- 150 mmHg
CO2- 0.21 mmHg
Describe the relationships between pressure and rate of diffusion and the concentration of gas molecules in the alveoli
Pressure is directional proportional to the concentration of the gas molecules
rate of diffusion is directly proportional to the pressure caused by that gas alone
What are the solubility values of O2 and CO2 and what does this difference do to the partial pressure?
O2= 0.024 CO2 = 0.57
Co2 is more soluble which means that it will exert a higher partial pressure
Define vapor pressure
Vapor pressure of water is the partial pressure exerted to escape the liquid phase form the gas phase
What is the vapor pressure at a normal body temperature?
47 mmHg
What is the relationship between temperature and vapor pressure?
Directly proportional
What are the factors that affect the rate of gas diffusion in a fluid?
- solubility of gas in the fluid
- cross sectional area of the fluid
- distance through which the gas must diffuse
- molecular weight of the gas
- temperature of the fluid
