Lung Volumes Flashcards
Inspiratory Reserve Volume (IRV)
The volume of air you breathe in after (on top of/in addition to) the tidal volume
Expiratory Reserve Volume (ERV)
- The volume of air you can force out in addition to the VT
- Requires activation of expiratory muscles (active expiration)
Residual volume
- No matter how hard you try, you cannot voluntarily force the air
- “Having the wind knocked out of you”-something forced you to exhale into RV
The Respiratory Capacities
- What is a capacity?
- How many are there?
- A capacity is the sum of two or more of the respiratory volumes
- There are four capacities
The Respiratory Capacities
- Influenced by?
- Absolute volume compared to % of predicted?
- % predicted based on?
- Size, gender, and age
- Absolute volume is less important than % of predicted
- % predicted is based on population norms and regression analysis
Vital capacity
- Inhale as deeply as you can then exhale all the air that you can (force it out at the end)
- VC = IRV + VT + ERV
Vital capacity
-Does not include residual volume allows VC to be measured via?
Spirometry
Inspiratory capacity
- Inhale as deeply as you can
- The total volume of air you can inhale from a normal resting point
- IC = IRV + VT
- Does not include RV-can be measured using spirometry
What volume cannot be measured using spirometry?
Residual volume
Functional Residual Capacity
- All the air that remains in your lungs at the end of a normal (passive) respiration
- FRC = ERV + RV
- INCLUDES RV so it CANNOT be measured using spirometry
Total Lung Capacity
- The total volume of air in your lungs after a maximal inhalation
- TLC = ERV + RV + IRV + VT
- INCLUDES RV-CANNOT be measured using spirometry
VC (vital capacity) equation?
VC = ERV + IRV + VT
IC (inspiratory capacity) equation?
IC = IRV + VT
FRC (functional residual capacity) equation?
FRC = ERV + RV
TLC (total lung capacity) equation?
TLC = ERV + IRV + VT + RV
3 types of dead space?
- Anatomic
- Alveolar
- Physiologic
Anatomic Dead Space
This is the conducting airways that were never meant to exchange O2 and CO2
Alveolar Dead Space
- Alveoli that get air, but do not get blood
- No exchange occurs here (because there is no blood to exchange with)
- As a result, the work it took to get the air into these alveoli is wasted
Physiologic Dead Space
The sum of anatomic and alveolar dead space
Reading assignments Respiratory physiology West
-Ch 2 pgs. 13-15 (FIG 2-2 especially), pgs. 15-16, pgs. 19-21
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You wish to measure a patients tidal volume. What instructions do you give the patient?
Breathe normally
The Respiratory Volumes
- Tidal volume (VT)-definition?
- Varies with circumstances such as?
- Amount of air inspired (or expired) in a single breath
- Varies with circumstances-resting versus exercise
