Chapter 31 Flashcards
What percentage of inhaled ventilation is wasted in the anatomical dead space?
30%
What is a good measurement in estimating the anatomical dead space?
Fowler’s single-breath N2 washout
What is a good measurement in estimating the physiological dead space?
Bohr’s expired CO2 approach
What is the 1st way to measure alveolar ventilation?
(Tidal volume - dead space) * Respiratory frequency
What is the 2nd way to measure alveolar ventilation?
Rate of CO2 production / Alveolar CO2 mole fraction
Alveolar ventilation is inversely proportional to?
Alveolar PCO2 and arterial PCO2
Alveolar ventilation is directly proportional to?
Alveolar PO2 and arterial PO2
Due to gravity, where is ventilation the greatest in the lungs, the base or the apex?
The base
What 2 diseases can exacerbate the nonuniformity of lung ventilation?
Restrictive pulmonary disease
Obstructive pulmonary disease
The pulmonary circulation has high or low pressure?
Low pressure
The pulmonary circulation has high or low resistance?
Low resistance
The pulmonary circulation has high or low compliance?
High compliance
If you increase the pulmonary arterial pressure, it reduces the?
Pulmonary resistance by recruiting and distending the pulmonary capillaries
In the pulmonary circulation (as opposed to the systemic circulation), hypoxia causes what?
Vasoconstriction (as opposed to vasodilation in the systemic circulation)
The greater the ventilation/perfusion ratio, the greater the?
Higher the PO2 and lower the PCO2
The ventilation/perfusion ratio is greatest at the base or apex of the lung?
The apex of the lung, due to gravity.
What does a high ventilation/perfusion ratio trigger?
Bronchoconstriction and a drop in surfactant production
What does a low ventilation/perfusion ratio trigger?
Compensatory hypoxic vasoconstriction
