Lecture 22 - Pulmonary Ventillation and Gas Laws Flashcards
What muscles are involved with inspiration and expiration?
L22 S10
Inspiratory muscle:
- diaphragm
- external interossei
- sternomastoids
- serratus anterior
- scalene muscles
Expiratory muscles:
(Passive at rest, muscles are used for forceful expiration)
-abdominal muscles
-internal intercostals
What are the pulmonary volumes?
L22 S14-15
Tidal volume:
- 500 mL
- volume inspired/expired per breath while at rest
Inspiration reserve volume:
- 3000 mL
- additional volume inspired with forceful inspiration
Expiratory volume:
- 1100 mL
- additional volume expired with forceful expiration
Residual volume:
- 1200 mL
- volume remaining in the lungs after forceful expiration
What are the pulmonary capacities?
L22 S15-16
Vital capacity:
- 4600 mL
- sum off all volumes that can be inspired or expired
Total lung capacity:
- 5800 mL
- sum of all volumes, both vital and residual
Inspiration capacity:
- 3500 mL
- sum of volumes above resting capacity (tidal volume and inspiration reserve volume)
Functional residual capacity:
- 2300 mL
- sum of volumes below resting capacity (expiratory reserve volume and residual volume)
What are minute and alveolar ventilation?
How are they calculated?
L22 S18
Minute ventilation:
- volume of gases moved into/out of lungs per minute
- breaths per minute * tidal volume (~.35 L)
Alveolar ventilation:
- volume of gases moved into spaces participating in gas exchange per minute
- (breaths per minute) * (tidal volume - dead space)
What are anatomical dead spaces and physiological dead spaces?
L22 S19
Anatomic dead space:
-trachea, bronchi, and bronchioles
Physiological dead space:
- anatomical dead space
- ventilated alveoli with poor/absent perfusion
Total dead space is roughly 1500 mL
What are pleural pressure and alveolar pressure?
How are they used to calculated transpulmonary pressure?
L22 S24
Pleural pressure:
-pressure of fluid between parietal pleura and visceral pleura
Alveolar pressure:
-pressure of air in the alveoli
Transpulmonary pressure:
-difference between alveolar pressure and pleural pressure
What is pulmonary compliance?
L22 S30
- volume by which the lungs expand for a given increase in transpulmonary pressure
- normal compliance is 200 mL per cmH20
- compliance = volume increase / pressure increase = distensibility * original volume
What effect does surface tension have on pulmonary function?
How is this countered?
L22 S35-36
- surface tension of water attempts to collapse the alveoli
- it is countered using surfactants
- without surfactants pressure would be greatly increased
What are the major components of air and their relative concentrations in the atmosphere and in the lungs?
L22 S38
Atmosphere:
- nitrogen: 78.09%
- oxygen: 20.95%
- argon: 0.93%
- carbon dioxide: 0.03%
Alveoli:
- nitrogen: 73.26%
- oxygen: 19.65%
- argon: 0.87%
- carbon dioxide: 0.03%
What are the gas laws?
L22 S39
Dalton’s law:
-total pressure of gases is equal to sum of partial pressures of individual gasses
Boyle’s law:
-for a fixed amount of an ideal gas at a constant temperature, pressure and volume are inversely proportional
Henry’s law:
-at a constant temperature, the amount of gas dissolved in a liquid is proportional to the partial pressure of gas in equilibrium in the liquid
How are partial pressures calculated?
L22 S44
-partial pressure = concentration of dissolved gas / solubility coefficient
What factors affect the rate of gas diffusion in a fluid?
L22 S46
- solubility of gas in a fluid
- cross-sectional area of the fluid
- distance the gas must diffuse
- molecular weight of the gas
- temperature of fluid
How is dead space calculated?
L22 S22
Comparing the amount of CO2 in arterial blood with the amount of blood in expired air
