Ventilation Flashcards
what is the function of the respiratory system?
to bring oxygen into the body from the environment and rid the body of the carbon dioxide produced by tissue metabolism
what is a spirometer?
the key tool used to measure respiration
- includes a cylinder of water with a floating drum in it
- inspiration = moves drum down = recording pen moves up
- expiration = drum moves up = recording pen moved down
what do the wave measurements mean in this graph from a spirometer mean?
what is inspiratory reserve volume (IRV)?
the volume of air from the end of normal inspiration (peak of resting tidal volume) to maximal amount of inspiration
= inspiratory capacity - resting tidal volume
what is resting tidal volume (RTV)?
the volume of air you can breathe in and out with no extra effort
= inspiratory capacity - inspiratory reserve volume
what is expiratory reserve volume (ERV)?
the volume of air you expire from the end of normal expiration to maximal expiration; the volume of forced expiration
= functional residual capacity - residual volume
what is residual volume (RV)?
the remaining air in your lungs that you cannot expel
= functional residual capacity - expiratory reserve volume
what is inspiratory capacity (IC)?
the sum of inspiratory volumes
= inspiratory reserve volume + resting tidal volume
what is functional residual capacity (FRC)?
the sum of the expiratory volumes; the total amount of volume remaining in the lungs at the end of quiet expiration
= expiratory reserve volume + residual volume
what is vital capacity (VC)?
the capacity of the lungs in which we are capable of inspiring and expiring
= inspiratory reserve volume + resting tidal volume + expiratory reserve volume
what is total lung capacity (TLC)?
the sum of all 4 basic volumes; the total volume of air the lungs can hold, inspire, and expire
what is a capacity?
the sum of 2 or more volumes
what are the average male values of lung volumes and capacities?
what is the significance of functional residual capacity (FRC)?
= RV + ERV
- it is the volume left in the lungs at the end of quiet expiration
- is the equilibrium point of respiratory system***
- requires no muscular effort
- balanced mechanical forces
what is minute ventilation?
generally is the expired volume in a given amount of time
what is dead space (Vd)?
the volume within the respiratory system where no gas exchange takes place
- not all of the inspired air goes to the alveoli so there is a lot of dead space in the lungs
what is the physiologic dead space?
the volume within the respiratory system where no gas exchange takes place
= anatomic + alveolar dead space
- is a greater value in older people
what is anatomic dead space?
- the volume of the conducting airways (bronchi, bronchioles, etc)
≈ an individual’s body weight in mL
i.e. 150 lb person = 150 mL of dead space - in younger people, anatomic dead space ≈ total dead space
what is alveolar dead space?
- the volume of the alveoli that are not perfused by pulmonary blood and therefore do not participate in gas exchange
- this volume increases as you get older so total dead space increases
how does respiratory mechanics work? (basic)
- to move air you need a pressure gradient between atm and alveoli (high to low)
- so when you inspire: barometric pressure has to be greater than alveolar pressure
- when you expired: alveolar pressure has to be greater than barometric pressure
what is the pleural space and its components?
what happens during inhalation (inspiration) to change the pressure gradient?
the diaphragm contracts and moves downward and outward to push the chest wall outward thus decreasing the pressure
what happens during exhalation (expiration) to change the pressure gradient?
the diaphragm relaxes and moves upward which decreases the volume in the ribcage, thus increasing the pressure to move air out
general mechanism of inspiration
what muscles are used during quiet breathing?
only “regular” muscles
- inspiration: diaphragm and external intercostals (btwn ribs)
- expiration: none - just relaxation
what muscles are used during forced inspiration and expiration?
regular and accessory muscles
- inspiration: scalenes, SCM, and trap
- expiration: internal intercostals, abdominal muscles
what is the primary muscle of breathing?
diaphragm
what is the action of the external intercostal muscles?
lift the ribs that lay below the muscle
how do we measure respiratory pressure?
units? relative to what?
- units: cm H2O
- pressure is relative to barometric pressure so if it’s positive it’s greater than barometric and if it’s negative then its less than barometric
what are the mechanical forces that influence respiration?
RECOIL (in the lungs and chest wall) and negative pressure (in the intrapleural space)
which direction do recoil forces go?
lung = inward recoil forces
chest wall = outward recoil forces
- these forces help make the intrapleural pressure more negative
what happens to the pressure during inspiration?
inspiration creates more negative pressure in the intrapleural space
