pk 1 - Partial Pressures and Dead Space Flashcards
What are the non-respiratory functions of the lungs? d m e h i t w-e p
defensive metabolic endocrine haemotologic immunologic thermoregulatory water-eliminative phonation
We need to breathe in order to …….
exchange O2 and CO2 with the atmosphere
The amount of CO2 and O2 we need to exchange depends upon our
metabolic rate, which increases with exercise
What is the respiratory quotient and what does it vary with?
VCO2/VO2. RQ referes to steady state conditions and depends only on the foodstuff being metabolised.
On a normal mixed diet RQ = 0.8. On a diet of carbohydrate only RQ = 1.0
What is used to measure metabolic rate?
What value is a typical basal metabolic rate?
What are the units of metabolic rate?
Usually measured as O2 consumption (flow of oxygen)
250ml/O2/min
The air we breathe is conditioned by ….., ……. and ….. before it reaches the delicate gas exchange regions of the ……………. ………
filtering, humidify and warming
respiratory zone
What 2 regions can the bronchial be divided into?
How does the movement of gases differ in each region?
How does the variation in CO2 and O2 differ in each region?
At which generation of the bronchial tree does gas exchange begin?
Conducting zone (1-16) - convection, huge variation Transitional and respiratory zones (17-23) - diffusion, little variation Generation 17
Starting the trachea and ending at the alveolar sacs, name the divisions of the bronchial tree
Trachea, bronchi, bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts, alveolar sacs.
Why is there a need for the term alveolar ventilation (VA) and why is the value of total ventilation (VE) not the same?
The fixed volume of air we breathe in does not read the gas exchange regions but remains within the anatomical deadspace. The actual amount of air that can usufully be exchanged per minute is termed VA
VA is matched to …………. …… The value of VA will ……….. if an alveolar deadspace aries, unless compensatory changes occur in ………
metabolic rate
decrease
VE
The bifurcating nature of the airways enables a ………… ……….. ….. to be held within a relatively small thoracic volume
large surface area
One consequence of the large surface area is that gas speed ……. from that observed at the mouth to that of …… in the respiratory exchange region. This makes gas movement in the respiratory zone dependent upon ……… ………… ………..
falls
diffusion
partial pressure differences
The partial pressure of a gas is defined as…..
What is the equation for partial pressure?
the pressure it would have if it existed on its own
fractional concentration of gas in a mixture x total pressure
Define physiological deadspace
the volume of gas within the respiratory system where gas exchange does not occur. It is made up of anatomical deadspace and a potential anatomical deadspace
What is the volume of anatomical deadspace in a typical adult male?
150ml
