Respiratory 2 Flashcards
What are fluids
Substance that continually deforms (flows) under an applied shear stress (gas,liquid)
What is normal sea level atmospheric pressure but what do respiratory physiologist set atmospheric pressure to
760 mmHg
Set to 0 cm H2O or mmHg
What is atmospheric air
Mixture of gases
Dalton’s law
Total pressure exerted by a mixture of gases is the sum of the pressure exerted by each gas
- Determines atmospheric pressure
What Dalton’s law dependent on
Humidity of air
Pressure exerted by one gas is known as
Partial pressure
PO2 PCO2
Partial pressure of gas=
Patm x % of gas in atmosphere
Partial pressure of gas in humid air=
(Patm - PH2O) x % of gas
What is bulk flow
Composition of gases moving
How does gas move in respiratory system
Down pressure gradients
From region of high pressure to low
What is flow directly inverse to
Resistance
What is flow directly proportional to
The pressure difference between alveolar pressure and atmospheric pressure
What are relevant pressure related to flow
Alveolar pressure: Palv (at end)
Atmospheric pressure: Patm (set to 0, at start right outside mouth)
During inspiration what decreases
Alveolar pressure to create gradient to move air in
During expiration what increases
Alveolar pressure increases to create gradient to move air out
Palv>Patm
Expiration
Palv<Patm
Inspiration
What does boyle’s law describe
Pressure-volume relationships
Change in lung volume results in a change in lung pressure driving bulk flow of air
What is boyle’s law equation
(P1V1=P2V2)
What happens to the pressure when the volume decreases to 0.5L?
P1V1=P2V2
100 mmHg x 1L = P2 x 0.5 L
200 mmHg =P2
Increased by 2
What happens during inspiration
Make volume of our alveoli larger resulting in drop in pressure below atm pressure resulting in air flow from atmosphere to alveoli
What is ventilation
Bulk flow exchange of air between the atmosphere and alveoli
What is a single respiratory cycle (one complete ventilation)?
Single inspiration followed by an expiration
What does spirometer measure
Lung volumes change
Tidal volume (TV)
Amount of air that enters or exits the lungs during quiet respiration (resting)
Tidal volume and frequency of breaths is
Total ventilation during rest
Total pulmonary ventilation
TV x frequency of breaths
Amount of air moving in than out
Inspiration reserve volume
Additional air that could still be inspired after quiet inspiration
Expiratory reserve volume
After end of quiet expiration, the volume of air that still remains within the lungs that can be expired
Residual volume
Air remaining in lungs even after maximal expiratory effort (cannot be measured with spirometer)
What are the four primary volumes that do not overlap and are the total lung capacity
Tidal volume, inspiratory reserve volume, expiratory reserve volume, residual volume
What are the two important functions of the air left
- Prevents airway collapse (small airways), after a collapse it takes large pressure to re-inflate
- It allows continuous exchange of gases
Total lung capacity
Sum of all 4 volumes
Functional residual capacity
Capacity of air remaining in the lungs after quiet expirations, the sum of ERV and RV
Inspiratory capacity
Sum of IRV and TV representing the max amount of air that one can inspire after quiet expiration
Vital capacity
Sum of IRV, TV, and ERV representing the max achievable air moved with a single breath (everything but residual volume)
What is a pulmonary function test
Testing individuals forced vital capacity (FVC) and comparing to Force expired volume in one second (FEV1)
What is low initial FVC indicative of
Restrictive pulmonary disease (decrease in lung compliance)
-COPD
What is FEV1 normally
~80% of vital capacity
What is below 80% of FEV1 indicative of
Obstructive pulmonary disease (increased resistance)
- asthma
How do we change alveolar pressure
Inspiratory muscle (skeletal) to increase the volume of alveoli, resulting in decrease in pressure
What is 60-75% of inspiratory volume change due to
Diaphragm (base of thoracic cavity)
Contracts and flattens
When is diaphragm relaxed
At end of expiration
What is the last 25-40% of inspiratory volume due to
Movements of rib cage
What muscles cause pump handle movement of sternum
External intercostals of upper ribs and scalenes
- move sternum outward
What muscles cause bucket handle motion of ribs
External intercostals in lower ribs
- lift ribs outward
