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52 Cards in this Set
- Front
- Back
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What is spirometry for?
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Measurig lung volumes
Measure volumes of inhaled or exhaled gas |
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What can the spirometer measure?
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Tidal volume
Vital capacity Inspiratory capacity Expiratory reserve volume Inspiratory reserve volume |
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What can a spirometer not measure?
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Functional residual capacity
Total lung capacity Residual volume |
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What is tidal volume?
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Amount of air inhaled/exhaled in one breath during quiet, relaxed breathing
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What is Inspiratory reserve volume (IRV)?
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Amount of air in excess if tidal respiration that can be inhaled with maximum effort
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What is expiratory reserve volume (ERV)?
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Amount of air in excess if tidal respiration that can be exhaled with maximum effort
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What is residual volume (RV)?
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Amount of air remaining in the lngs after maximum expiration; keeps alveoli inflated between breaths and mixes with fresh air on next inspiration
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What is vital capacity (VC)?
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Amount of air that can be exhaled with max effort after max inspiration (ERV + TV + IRV)
Used to asses strength of thoracic muscles and pulmonary function |
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What is inspiratory capacity?
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Max amount of air that can be inhaled after a normal tidal expiration (TV + IRV)
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What is functional residual capacity?
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Amountof air remaining in the lungs after a normal tidal expiration (RV + ERV)
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What is total lung capacity (TLC?)
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Max amount of air the lungs can contain (RV + VC)
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How can FRC be measured?
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Helium dilution
FRC= (C1 x V1/C2) - V1 (C1V1= C2 x (V1+FRC)) FRC= RV+ ERV |
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What is ventilation?
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Amount of air inspired into the lungs over a period of time
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What is Ve?
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Amount of air inspired/expired in 1 minute
Ve= Vt x f (Vt = tidal volume, f= frequency of breaths/min) |
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What is the anatomical dead space?
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Air that gets trapped in the conducting vents and never reached the alveoli (area of gas exchange)
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What is the volume of the anatomical dead space in an adult?
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150 ml
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What is the normal tidal volume (Vt) and f in an adult male?
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Vt= 500 ml
f= 12 breaths/min |
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What is alveolar ventilation?
How much is it? |
Amount of air that reaches the respiratory zone per minute and available for gas exchange
Va= (Vt-Vdead space) x f Va= (500-150) x 12 |
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How is the volume of the anatomical dead space measured?
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Close to subject's weight in pounds
(150 lbs = 150 ml) |
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What hppens when a certain amount of inspired air reaches the respiratory zone but does not take part in gas exchange?
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Alveoli get decreased or no bloood supply
=> Alveolar dead space |
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What is the physiological dead space?
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Alveolar + anatomical dead space
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What is the difference between the minute and alveolar ventilation?
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The dead space ventilation that is wasted from the gas exchange point of view
(Vd= Vt-Va) |
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What is normal alveolar ventilation?
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Va matches CO2 and keeps Pa(arteriole)CO2 at a constant level
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What is the distribution of CO2 in the blood/veins/arteries?
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CO2 high in venous blood
CO2 low in alveoli |
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What is the distribution of O2 in the blood/veins/arteries?
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High O2 in atmosphere
Lower O2 in alveoli |
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How does gas exchange occur?
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Need a P gradient
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What is alveolar hyperventilation?
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More O2 supplied and more CO2 removed than the metabolic rate requires (Ve exceeds the needs of the body)
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What happens during alveolar hyperventilation?
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Alveolar partial P of CO2 drops
Alveolar partial P of O2 rises ->ventiltion has to be compared to metabolism .: ventilation during exercise is not hyperventilation |
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What is alveolar hypoventilation?
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Fall in th overall level of ventilation that can redeuce alveolar ventilation below that required by the metabolic activity of the body
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What happens during alveolar hypoventilation?
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Rate at which O2 is added and CO2 is removed is lowered so that alveolar partial P of O2 drops and alveolar partial P of CO2 rises
.: blood in pulmonary caps is less O2'd and PaO2 falls below normal levels while PaCO2 rises above normal |
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When can alveolar hypoventilation occur?
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Severe lung disorders
Chronic obstructive lung disease Damage to respiratory muscles Chest cage is injured/lung collapse When CNS is depressed |
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What happens to alveolar P O2 and P CO2 when:
breathing with low P O2? |
P O2: Dec
P CO2: unchanged |
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What happens to alveolar P O2 and P CO2 when:
Alveolar ventilation increases and metabolism is unchanged? |
P O2: Increases
P CO2: Decreases |
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What happens to alveolar P O2 and P CO2 when:
Alveolar ventilation decreases and metabolism is unchanged? |
P O2: Decreases
P CO2: Increases |
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What happens to alveolar P O2 and P CO2 when:
Alvolar ventilation is unchanged and metabolism is increased? |
P O2: Decreases
P CO2: Increases |
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What happens to alveolar P O2 and P CO2 when:
Alvolar ventilation is the same and metabolism is decreases? |
P O2: Increases
P CO2: Decreases |
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What is Fick's law?
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Diffusion
Rate of diffusion of a gas is proportional to: -Surface area (of the tissue) -Partial P gradient (the difference in gas partial pressure between the 2 sides) Inversely proportional to the tissue thickness |
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What is the diffusion rate proportional to?
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Surface area
Partial P 1/thickness |
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What is the diffusion direction for passive diffusion?
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Higher to lower concentration
(O2 diffuses from alveolar gas to blood, CO2 diffuses through the alveolar-capillary mb to a liquid plasma in the pulmonary capillaries) |
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How cana gas diffuse through a liquid?
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If its soluble in that liquid
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Which diffuses faster: Co2 or O2?
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CO2 because it can diffuse ~20x more rapidly then O2
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What happens as flow continues?
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Rate of diffusion decreases (cuz you get a smaller P gradient, since more and more O2 diffuses from caps to blood)
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How does the diffeence in PCO2 between the 2 sides of the alveolar-capillary mb compare to O2?
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10x smaller than O2
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.: why doesn't O2 diffuse much faster then CO2?
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Other factors involved
Diffusion rate of CO2 exceeds that of O2, cuz CO2 is more soluble in blood .: time required to get equilib btw alveolar air and cp blood is about the same |
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What is transit time?
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Time it takes for the gases to diffuse
Amount of time it takes for blood to go from the pulmonary artery to the pulmonary vein (for RBCs to get saturated in O2 and desat in CO2) |
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What is the transit time for pulm caps at rest?
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0.75 s
-> tis fast diffusion of PO2 in the air and blood reach equilib before the blood has passed halfway along the pulmonary cap |
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What happens duing transit time?
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Blood in caps is in contact with the air in the alveoli
Diffusion of the gases occus along the P gradient -> normal lung: diffusion of O2 and CO2 is done with 1/3 RBC transit time |
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What happens with a resting person with impaired rate of diffusion?
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->could be a patient with pulmonary edema
P O2 & P CO2 could be normal (might still be able to diffuse through during transit time) ->when blood flow inc and transit time gets shorter, arterial P O2 can decrease and arteriole P CO2 may increase |
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What happens to blood in the caps?
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Blood gets O2'd
Blood gets de-CO2'd |
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What would happen if the alveolar mb was thicker?
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Would have more succes vd regular viruses
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What are the partial P in the pulmonary arteries?
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P O2: 40mm Hg
P CO2: 46mm Hg |
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What are the partial P in the pulmonary veins?
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P O2: 100mm Hg
P CO2: 40mm Hg |
