Pulmonary Function Background Flashcards
What is respiration
Process by which body obtains and utilizes O2, and produces and eliminates CO2
What are the 5 parts of respiration
- Pulmonary ventilation
- Pulmonary gas exchange
- Gas transport
- Tissue/blood exchange
- Cellular respiration
What is pulmonary ventilation
movement of gases btwn lungs and environment
What is pulmonary gas exchange
movement of gases btwn lungs and bloodstream
What is gas transport
movement of gases w/in bloodstream
What is tissue/blood exchange
movement of gases btwn bloodstream and tissues
What is cellular respiration
consumption of oxygen and production of CO2
What are factors that influence diffusion
- SA
- diffusion distance
- Conc gradient
Total area of alveoli is size of
tennis court
How is high conc gradient ensured
- movement of blood with low O2 and high CO2 lvls to lungs
2. pulmonary ventilation (breathing), which maintains high lvl of O2 and low lvl of CO2 in alveolar air
How is ventilation of human lung produced
Muscular contractions
What is tidal volume
Amt of air moving into and out of the lungs in one breathing cycle
What is vital capacity
Maximal amt of air that can be moved thru the lungs
Diff btwn tidal volume and vital capacity
Reserve volumes
How to alter (inc) the amt of air moving into and out of lungs
- Inc depth of breathing
2. Inc rate of breathing
What controls both the depth and rate of breathing
Respiratory control center located in medulla
Dry air contains what 4 gases and their conc?
- Nitrogen - 78.04%
- Oxygen - 20.98%
- Trace gases - 1.00%
- CO2 - 0.03%
What is the O2 gas fraction?
0.2093
Which gases are physiologically inert and which are active gases
- physiologically inert: nitrogen and trace gases
2. physiologically active: O2 and CO2
Why are compressed gases dried b4 placed in cylinder
Prevent rust
When are wet gases dried
B4 being sampled in gas analyzer
What are the proper SI units for gas pressure
- Pascals ( 1 Pa = 1 N x m^2)
2. kilopascasls (kPa)
What units is gas pressure often expressed as
mmHg
How is gas pressure measured using U tube?
- U tube with mercury connected at one end to gas, gas would “push down” on mercury, causing it to go down one arm of the U-tube and rise up the other arm of U-tube
- Once mercury stops moving, gas pressure equal to diff in height (mm) btwn mercury lvls in two arms of U-tube
Why is impractical to express gas pressure in cm H2O for atmospheric pressure
density of water so much lower (13x) than mercury, need very long U-tube
Atmospheric pressure/barometric pressure _____ with proximity to earth’s centre
increases
What is ~barometric pressure at Sea level vs. SFU vs. mount everest
760 vs. 720 vs. 250
What is barometric pressure
sum of the each gas in the atmosphere exerting their individual pressure
What is the partial pressure of a gas
Product of barometric pressure and gas fraction
What is the partial pressure of oxygen, nitrogen, and CO2 at SFU?
- PN2 = 730 mmHg x 0.7904 = 577 mmHg
- PCO2 = 730 mmHg x 0.0003 = 0.2 mmHg
- PO2 = 730 mmHg x 0.2093 = 152 mmHg
The volume occupied by a given # of gas molecules varies inversely with _____ and directly with _____
PRESSURE (Boyle’s Law) and directly with TEMPERATURE (Charle’s Law)
What is the ambient temperature and pressure saturated (ATPS)
Conditions of temp and pressure at time respiratory gas volume is measured
What are the 2 reference conditions of temp and pressure
- STPD: Standard temp and pressure dry
2. BTPS: Body temperature and Pressure Standard
What is relative humidity
Amt of water vapour in given volume of air relative to the maximal amt of water vapour which could be in that volume of air before its saturated, multiplied by 100%
What is the standard temp and standard pressure
0 degree C and 760 mmHg
One mole of ideal gas at STPD contains _____ molecules and occupies ____ Litres
6.02 x 10^23 molecules and occupies 22.4 Litres
When do corrections of gas volumes from ATPS to STPD occur
Are made whenever we need to know the AMT OR # OF GAS MOLECULES e.g. when calculating amt of O2 consumed and amt of CO2 produced
What is the formula for STPD factor
( PB - VP )/760 x 273(273+T)
where PB = ambient barometric pressure (mmHg)
T = ambient temp (degree C)
VP = partial pressure of water vapour (mmHg)
What does VP (partial pressure of water vapour) depend on
RH, temp, and pressure
Calculate VE (STPD) if VE (ATPS) was 30 L, PB was 740 mmHg, T was 20 degree C, VP was 17.5 mmHg
VE (STPD) = VE (ATPS) x (PB-VP)/760 x 273/(273+T)
VE (STPD) = 30 L x (740-17.5)760 x 273/(273+20)
VE (STPD) = 26.6L
When do corrections of gas volumes from ATPS to BTPS occur
Are made when we’re interested in knowing the VOLUME OF GAS that’s ventilated by lungs and not the # of gas molecules present
What is BTPS
refers to original intrapulmonary volume the exhaled gas would occupy at ambient barometric pressure, saturated w/water vapour at body temp
Equation of BTPS factor?
(PB-VP)/(PB-47) x (273+37)/(273+T)
where PB = ambient barometric pressure (mmHg)
T = ambient temp (degree C)
VP = ambient partial pressure of water vapour (mmHg)
47 = constant partial pressure of water vapour in the lung (mmHg)
Calculate VE (BTPS) if VE (ATPS) was 30 L, PB was 730 mmHg, T was 23 degree C, VP was 21.1 mmHg
VE (BTPS) = VE (ATPS) x (PB-VP)/(PB-47) x (273+37)/(273+T)
VE (BTPS) = 30 x (730-21.1)/(730-47) x (310)/(273+23)
VE (BTPS) = 32.7 Litres
At SFU, the STPD correction factor and BTPS correction factor will almost always be in what ranges
STPD: 0.85-0.90
BTPS: 1.05-1.10
2 types of spirometers
- water-seal spirometer
2. dry rolling-seal spirometer
Compare water-seal spirometer vs. dry rolling-seal spirometer
- water-seal spirometer: large bell suspended in water. Volume of air in bell recorded on motor-driven drum and flow rates obtained from measurements of slope of the volume change. CLOSED CIRCUIT SPIROMETRY SYTEM. Accumulation of CO2 prevented by passage of exhaled gas thru baralime pellets
- dry rolling seal: piston in a cylinder. has potentiometer thats activated by movement of piston to provide electrical output for volume and flow. potentiometer is transducer that changes mechanical motion into electrical signal. electrical output from potentiometer sent thru interface/A-D converter into computer.
Describe pneumotachographs
consists of resistance e.g. fine-mesh screen, and differential pressure transducer to detect PRESSURE DROP across resistance occurring during gas flow. signal from pressure transducer can be electronically integrated for given interval to derive volume measurement. electrical output produced interfaced to computers
The iWork flowhead example of what
Pneumotachograph
2 types of plethysmograph
- whole body plethysmograph
2. impedance plethysmograph
Compare whole body and impedance plethysmograph
- whole body plethysmograph: airtight sealed box subject enclosed and breathes via mouthpiece. Changes in thoracic volume recorded from the changes in pressure or volume in box. Obtains alveolar pressure in studies of airway resistance and compliance
- Impedance plethysmograph: Makes use of changes in transthoracic electrical impedance to provide measure of changes in lung volume
Describe volume turbines
Inspired and or expired air passed thru turbine. The more air that passes, the greater spinning rate of propeller. # of propeller rotations summed and value proportional to volume of air passed by propeller. Measures volume and flow rates in Spirolab II pulmonary fxn testing device
Define minute ventilation (VE)
volume of gas exchanged per min at rest or during any stated activity.
- it’s tidal volume x # of respirations per min
Define tidal volume (VT)
volume of air either inspired or expired w/each breath at rest or during any stated activity
Define vital capacity (VC)
greatest volume of gas that can be expelled by voluntary effort after maximal inspiration
- subject should expire moderate rate not forcefully
Define inspiratory capacity (IC)
maximal volume that can be inspired from resting end-expiratory position
Define expiratory reserve volume (ERV)
maximal volume that can be exhaled from resting end-expiratory position
Define functional residual capacity (FRC)
Volume of gas remaining in lungs at end of quiet exhalation, composed of expiratory reserve volume and residual volume
What is residual volume (RV)
volume of gas remaining in lungs after maximal expiration
What is total lung capacity (TLC)
volume of gas in lungs at time of maximal inspiration; it is composed of sum of vital capacity (inspiratory capacity + expiratory reserve volume) and the residual volume
What is residual volume - total lung capacity ratio (RV/TLC x 100)
expresses the % of total lung capacity occupied by residual volume
- as a fraction of TLC, RV inc from approx 25% at age of 20 yrs to 40% at age 70
What is maximum breathing capacity (MBC)
max volume of respired gas which may be breathed during max effort
- estimated from a 12 s period of hyperventilation at rest and expressed as a volume per min by multiplying the 12 s value by 5
What is forced vital capacity (FVC)
after max inspiration, subject expires maximally as hard and as fast as possible
What is forced expiratory volume in 1 sec (FEV1)
volume of air expired during first 1 sec of forced vital capacity maneuver
What is maximal mid-expiratory flow rate (MMFR)
maximal flow rate of air achieved over the middle 50% of forced vital capacity maneuver.
Chronic pulmonary dysfxn can be divided into what 2 categories
- obstructive disorder
2. restrictive disorder
what is obstructive disorder
- BLOCKAGE or NARROWING of airways causing INC AIRWAY RESISTANCE
- bronchiolar obstruction can result from inflammation and edema
- asthma, bronchitis are obstructive disorders
- MMFR and FEV1 are dec, and FEV1/FVC ratio less than 70%
- air trapping inc FRC, RV, and TLC
What is restrictive disorder
- airways ok but damage to LUNG TISSUE resulting in DEC ELASTICITY and DEC COMPLIANCE = hard to expand lung
- pulmonary fibrosis and pneumonia are restrictive disorders
- a lung volumes reduced (slow VC, FVC, RV, FRC, TLC) cause lung tissue stiff and can’t expand
- MBC, peak expiratory flow rate, FEV1, MMFR are reduced
- FEV1/FVC ratio higher than 90%
is max mid-expiratory flow rate reduced more in obstructive or restrictive disorder
obstructive
Example of how patient can have both restrictive and obstructive disorder
Coal miner who smoked 1 pack of cigs per day for 20 days (obstructive from smoking and restrictive from exposure to dust in coal mine)
