resp 2 Flashcards
what is the similar aspects of flow between the blood flow and respiratory air flow?
-mainly the pressure gradients created to cause flow
-both are fluids
-blood pressure and atmospheric pressure are reported in mm Hg
what are fluids?
-a substance that continually deforms (flows) under an applied shear stress (gas, liquid)
what is cm H2O and normal sea level atmospheric pressure?
cm H2O, where 1 mm Hg=1.36 cm H2O or kPa when 760mm Hg-101.325 kPa
-normal sea level atmospheric pressure is considered to be 760 mm Hg but is usually set to 0cm H2O or mm Hg by respiratory physiologists
what is Daltons law?
the total pressure exerted by a mixture of gases is the sum of the pressure exerted by each gas
-also dependent on humidity (water vapour) of the air
-the pressure exerted by one has is known as its partial pressure (we are interested in PO2 and PCO2 specifically)
what is the mixture of gases in atmospheric air?
example of how to calculate partial pressure
air moves by ____________
BULK FLOW: from a region of high pressure to low pressure described by
what are the relevant pressures?
-alveolar pressure: Palv
-atmospheric pressure: Patm (set to 0)
what does boyle’s law help explain?
-described pressure-volume relationships
-helps explain how a change in lung volume results in a change in lung pressure driving the bulk flow of air
how does boyle’s law relate to the volume of the alveoli?
during inspiration we make the volume of out alveoli larger resulting in a drop in pressure below atmospheric pressure resulting in air flow from the atmosphere into our alveoli
what is ventilation (breathing)?
-is the bulk flow exchange of air between the atmosphere and the alveoli
-a single respiratory cycle consists of a single inspiration followed by an inspiration
-lung volumes change during
what is a spirometer?
what is tidal volume (TV)?
-total ventilation during rest represents the product of tidal volume and frequency of breaths
what is the total pulmonary ventilation?
TV x frequency of breaths
what are the four primary volumes that do not overlap?
- tidal volume
- inspiratory reserve volume
- expiratory reserve volume
- residual volume
what are the two important functions of lung volumes?
-prevents airway collapse, after a collapse it takes an unusually large pressure to re-inflate it
-it allows continuous exchange of gases
what is inspiratory reserve volume (IRV)?
-the additional air that could still be inspired after quiet inspiration is IRV
what is expiratory reserve volume (ERV)?
-at the end of quiet expiration, the volume of air that still remains within the lungs that can be expired is known as the ERV
what is residual volume?
-even with maximal expiratory effort, air remains in the lungs
-cannot be measured with spirometer
graph of a spirometer tracing showing lung volumes and capacities
what are the four primary volumes for lung capacity?
- total lung capacity
- functional residual capacity
- inspiratory capacity
- vital capacity
what is total lung capacity?
-the sum of all 4 volumes
what is functional residual capacity?
-the capacity of air remaining in the lungs after quiet expiration
-sum of ERV and RV
what is inspiratory capacity?
-the sum of IRV and TV
-representing the maximal amount of air that one can inspire after quiet expiration
what is vital capacity?
-the sum of IRV, TV and ERV representing the maximal achievable air moved with a single breath
what is a pulmonary function test?
-involves testing an individuals forced vital capacity (FVC) and comparing it to their forced expired volume in one second (FEV1)
how is obstructive and restrictive shown using pulmonary function test?
-low initial FVC indicative of restrictive pulmonary disease (decrease in lung compliance)
-FEV1 is normally 80% of vital capacity
-below 80% indicative of obstructive pulmonary disease (increased resistance)
when does inspiration occur?
when alveolar pressure decreases
how do we change alveolar pressure?
-according to boyle’s law, an increase in volume will cause a decrease in pressure
-we use our inspiratory muscles (skeletal) to increase the volume of alveoli, resulting in a decrease in pressure
-60-75% of inspiratory volume change due to diaphragm
what contributes to inspiration volume change?
-60-75% of inspiratory volume change due to diaphragm
-movements of the rib cage accounts for the rest (25-40%)
how does the ribcage move for inspiration?
-external intercostals of upper ribs and scalenes attached to sternum cause “pump handle” motion
-external intercostals in lower ribs create “bucket handle” motion
graph of intercostals
when does expiration occurs?
-when alveolar pressure increases
-quiet expiration is passive (relaxation of the inspiratory muscles)
