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23 Cards in this Set

  • Front
  • Back
what is the airflow equation?
F (flow rate) = change in P (P gradient)/resistance
what is compliance?
it is the effort requried to stretch (distend) the lungs
what 2 things does pulmonary elastic behavior depend on?
1. pulmonary elastic connective tissue
2. alveolar surface tension
what does pulmonary surfactant do?
it prevents the alveolus from collapsing from the alveolar surface tension
waht is pulmonary surfactant composed of?
pulmonary surfactant is a mixture of proteins and lipids secreted by type II alveolar cells, it is found between water molecules in fluid lining alveolus, it reduces alveolar surface tension
what are the 2 benefits of reducing alveolar surface tension with pulmonary surfactant?
1. increases pulmonary compliance, reducing work required to inflate lung
2. reduces lungs tendency to recoil, so they do not readily collapse
what 4 situations increase the amount of work neccessary to breathe?
1. decreased pulmonary compliance: pulmonary fibrosis
2. increased airway resistance: COPD
3. decreased elastic recoil: emphysema
4. need for increased ventilation: exercise
about how many mL are inspired and expired during each quiet breathing cycle?
500 mL (tidal volume)
what is the range of lung volume?
1200-5700 mL
what is the tidal volume?
tidal volume is the air entering or leaving lungs in a single breath
what does the tidal volume average?
500 mL
what is pulmonary ventilation?
it is the volume of air breathed in and out in one minute
what is the respiratory rate?
it is the number of breaths/minute
what is the equation for pulmonary ventilation?
pulmonary ventilation = tidal volume (mL/breath) * respiratory rate (breaths/min)
what is anatomical dead space?
it is not all inspired reaches alveoli, where gas exchange can occur, some in conducting airways, alveolar ventilation is less than pulmonary ventilation ebcause of anatomic dead space
what is the equation for alveolar ventilation?
alveolar ventilation = (tidal volume - dead space volume)/breath * respiratory rate
average alveolar ventilation = (500 mL - 150 mL)/breath * 12 breaths/min = 4200 mL/min
what happens when CO2 accumulates in the alveoli?
Accumulation of CO2 in alveoli: decreases airway resistance by causing airway supplying alveoli to relax
what happens when there is decreased CO2 in alveoli?
decreased CO2 in alveoli has opposite effects: increased contraction of airways supplying alveoli, reduced airflow
what is the oxygen parital pressure gradient from alveoli to blood across pulmonary capillaries?
60 mmHg (100 to 40)
what is the carbon dioxide parital pressure gradient from blood to alveoli across pulmonary capillaries?
6 mmHg (46 to 40)
what is the oxygen parital pressure from blood to tissue cell across systemic capillaries?
60 mmHg (100 to 40)
what is the carbon dioxide partial pressure gradient from tissue cell to blood across systemic capillaries?
6 mmHg (46 to 40)
what are other factors affecting rate of gas transfer?
SA, distance, gas diffusion coefficient