Respiratory Physiology I Flashcards
what do we use to measure lung function? how does it work?
lung function: spirometry test amount of air you move inot and out of lungs during rest
- seated during the test
- a soft clip will be placed on nose to stop air escaping from it
- inhale fully, so your lungs are completely filled with air
- close your lips tightly around the mouthpiece
- exhale as quickly and forcefully as you can, making sure you empty your lungs fully
This will normally need to be repeated at least 3 times to ensure a reliable result.
what is
- tidal volume?
- forced vital capacity?
- Inspiratory reserve volume?
- Expiratory reserve volume?
- Residual volume?
tidal volume: the amount of air you move into and out of your lungs during rest
Forced vital capacity Is the maximum volume of air into and out of your lungs in a single respiratory cycle
Inspiratory reserve volume is the volume of air you can draw into your lungs
Expiratory reserve volume is the volume of air you can expel from your lungs
Residual volume is the volume of air that remains in your lungs, even after maximum exhalation.
how do you calculate forced vital capacity? (2)
1) forced vital capacity = Inspiratory reserved volume + tidal volume + expiratory reserve volume
2) forced vital capacity = Inspiratory capacity + expiratory reserve volume
what is FEVI?
what can influence FVC and FEVI? (2)
- FEVI = volume of air exhaled in in first second of forced exhalation
- height
- age (decreases with age)
What is FEVI / FVC? - what does it show?
what is normal FEVi/FVC?
where might you see abnormal FEVi/FVC?
- after completely filling lungs and undertake forced exhalation manouvre, you have exhaled X amount of entire force vital capacity
- *normal FEVi/FVC:** 70-80%
- *abnormal FEVi/FVC:** due to airflow limitation, for example asthma
what does flow volume loop measure?
what is on x and y axis?
how do u do it?
how do you measure FVC from volume loop measure?
flow volume loop: measures flow (L/s) (y axis) versus volume (L) (x axis)
- subject fills lungs to maximum, place tight seal around spirometry mouth piece
- subject exhales as much as possible: progesses along x axis
- for every volume air exhaled out, the device measures the corresponding airflow of y axis
force vital capacity: volume measure alonged x axis / the volume exhaled !
how does loop change due to asthma?
asthma: significant airflow limitation - as patient exhales out, the airflow able to produced on y axis is reduced
explain how inspiration occurs (quiet and forced)
During quiet inspiration, this process is active:
- involuntary response
- contraction of diaphragm - thoracic volume increases and drop in pressure
- diaphragm flattens by 1-2 cm
- external IC muscles contract - rip cage up and out
Forced inhalalation
- the diaphragm, external intercostal muscles & accessory muscle used (pectoralis major and minor, and the serratus anterior)
- diaphragm flattens by <10 cm
- pump handle & bucket handle movements cause increase in pressure
how does quiet and forced expiration occur?
Quiet expiration:
- is largely passive: result of elastic recoil of the lungs
Forced expiration
- active
- accessory respiratory muscles: anterior abdominal muscles and quadratus lumborum
which external i/c muscles are used for forced inhalation (3) and exhalation (2) ?
forced inhalation: pectoris major, minor and serratus anterior
forced exhalation: anterior abdominal muscles - external oblique & rectus abdominis and quadratus lumborum
what is alveolar ventilation?
what do hypo- or hyperventilation show?
* what is movement of gasses in defined by in alveoli? *
- alveolar ventilation: portion of the total ventilation that reaches the alveoli and participates in gas exhchange
- hypo- or hyperventilation show signs of lung disease
- movement of gasses in defined by partial pressure gradients
explain, using this graph
- where in the lungs ventilation and perfusion are greatest?
- why? ^
- why ventilation / perfusion ration increases as you go up lung
ventilation and blood flow are higher at base of the lung than the apex
why?
1) ventilation: weight of fluid in plueral cavity increases the interpleural pressure at the base to a less negative value. Therefore, alveoli are less expanded and have higher compliance = more substantial increase in volume when inspiration occurs.
2) blood flow / perfusion: gravity pulls blood towards the base, so get increase in hydrostatic pressure
BUT at base:
- perfusion is far greater at base of lung than ventilation -> why you get an increase in airway venitlation and perfusion ration as go up lungs
where in lung is ventilation and perfusion greatest? at this location - which occurs more - perfusion or ventilation?
ventilation and blood flow are higher at base of the lung than the apex
BUT
perfusion is far greater at base of lung than ventilation
what is anatomical dead space? what volume is anatomical dead space?
what is alveolar dead space?
- *anatomical dead space:
- ** the air of the respiratory tract that only conducts the air rather than involved in gaseous exchange
- mouth, pharynx, trachea and bronchi up to the terminal bronchioles
- approximately 150ml (out of 500ml average inhaled)
- *alveolar dead space:
- **due to age or resp disease
- alveoli that have insufficient blood supply to act as effective respiratory membranes.
