Conducting and Respiratory Zones
Typically, no gas exchange occurs until after branch (z) 17 or so.
Abbreviations in Respirology
P = partial pressure of a gas
S = saturation of hemoglobin
a = arterial
A = alveolar
V = volume (in L)
VE = minute ventilation (ventilation per min)
VT = tidal volume (~500cc/min)
The lung volume representing the normal volume of air displaced between normal inhalation and exhalation when extra effort is not applied. In a healthy, young adult, tidal volume is approximately 500mL per inspiration.
pH / PaCO2 / PaO2 / HCO3
Anatomical vs. Physiological Dead Space
Anatomical dead space is the portion of the airways (such as the mouth and trachea to the bronchioles) which conducts gas to the alveoli. No gas exchange is possible in these spaces.
Physiological dead space / alveolar dead space is the sum of the volumes of those alveoli which have little or no blood flowing through their adjacent pulmonary capillaries. Physiological/alveolar dead space is negligable in healthy individuals, but can increase dramatically in some lung diseases due to ventilation-perfusion mismatch.
Is a measurement used to assess the efficiency and adequacy of the matching two variables of ventilation and perfusion.
V - ventilation - the air that reaches the alveoli
Q - perfusion - the blood that reaches the alveoli
Can be measured with a ventilation/perfusion scan
The most common of pulmonary function tests (PFTs). Measures lung function, specifically the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled.
PACO2 vs. PaCO2
They are basically equivalent
Oxygen Uptake Along the Pulmonary Capillary
Normally, the time the blood comes into contact with the alveoli is 0.75 seconds. When you are doing physical exercise, this time drops to 0.25 seconds.
Cardiac output decreases the time spent in contact with the alveoli, and can decrease the amount of oxygen that is being absorbed.