overview of pulmonary function Flashcards
total ventilation definition
the total volume of air leaving the lung each minute, measured in ml per minute
is the volume inspired greater than the volume expired?
yes, as more oxygen is taken in than carbon dioxide given out
dead space definition
the volume of air that is inhaled that does not take part in gaseous exchange
name two different types of dead space
anatomical and alveolar
explain anatomical dead space
the portion of airways, such as the mouth and trachea that conducts gas to the alveoli but no gaseous exchange occurs here as there is no perfusion
alveolar dead space explained
the sum of the volumes of those alveoli that have little or no blood flowing through their adjacent pulmonary capillaries, so alveoli that are ventilated but not perfused, and thus where no gas exchange can occur
alveolar ventilation definition
the volume of fresh gas entering the respiratory zone each minute (removing the volume that remains in the anatomical dead space)
partial pressure definition
the pressure of that constituent gas if it alone occupied the entire volume of the original mixture at the same temperature
why is the partial pressure of gases important?
it is a measure of the gas molecule’s thermodynamic activity
gases dissolve and diffuse and react according to their partial pressures, not their concentration
unit of partial pressure
pascals, atm, kPa, units of gas per volume
resting oxygen consumption
250ml/min
maximum oxygen consumption
3000ml/min
respiratory quotient definition
number used in calculations of the basal metabolic rate, estimated from carbon dioxide production relative to the oxygen consumed by the body
normal alveolar partial pressure of oxygen
90 mmHg, 12kPa, range 80-100mmHg, 11-13 kPa
normal alveolar partial pressure of carbon dioxide
40mmHg 5.3kPa, range 35-45mmHg, 4-6kPa
what is the normal alveolar partial pressure similar to?
normal arterial values
alveolar gas equation definition
an equation that allows the calculation of the alveolar partial pressure of oxygen from data that is practically measurable
tidal volume definition
the volume of air that moves into and out of the lungs in one normal breath, 500ml
vital capacity definition
amount of gas that can be exhaled by maximal inspiratory effort, following maximal inhalation, 5L