Ventilation and Compliance Flashcards
(36 cards)
Describe what it means by tidal volume?
TV - Tidal Volume. The volume of air breathed in or out of the lungs at each breath.
500ml
Describe what it means by expiatory reserve volume?
ERV - Expiratory Reserve Volume. The maximum volume of air which can be expelled
1100ml
Describe what it means by inspiratory reserve volume?
IRV - Inspiratory Reserve Volume. The maximum volume of air which can be drawn
3000ml
Describe what it means by residual volume?
RV - Residual Volume. The volume of gas in the lungs at the end of a maximal expiration.
1200ml
Describe what it means by vital capacity?
VC - Vital Capacity = tidal volume + inspiratory reserve volume + expiratory reserve volume.
Describe what it means by total lung capacity?
TLC - Total Lung Capacity = vital capacity + the residual volume.
Describe what it means by inspiratory capacity?
IC - Inspiratory Capacity = tidal volume + inspiratory reserve volume.
Describe what it means by function residual capacity?
FRC - Functional Residual Capacity = expiratory reserve volume + residual volume.
Describe what it means by FEV1?
FEV1 = Forced Expired Volume in 1 second
Describe what it means by FEV1:FVC?
Fraction of Forced Vital Capacity expired in 1 second.
What does it mean by anatomical dead space and what is the value for this?
Anatomical dead space volume is ~150 mL and is the volume of gas occupied by the conducting airways that cannot undergo gas exchange.
What does ventilation refer to?
Ventilation refers to the movement of air in and out of the lungs (breathing).
What are the two types of ventilation and describe each one
Pulmonary (minute) ventilation – total air movement in and out of the lungs
Alveolar ventilation – fresh air (with high O2 content) getting to the alveoli and therefore available for gas exchange.
What does hypoventilation mean?
Hypoventilation is when our alveolar ventilation is low.
What does hyperventilation mean?
Hyperventilation is when our alveolar ventilation is high.
How can alveolar ventilation be calculated?
Alveolar ventilation (mL/min) can be calculated by the respiratory rate (breathes per minute) and the air to alveoli (mL/min).
What does partial pressure mean and what unit is it expressed by?
The partial pressure of a gas in a mixture of gases is equivalent to the percentage of that particular gas in the entire mixture multiplied by the pressure of the whole mixture.
Pressure is common expressed in mmHg or kPa units (normally use mmHg)
T/F All gas molecules exert same pressure, so partial pressure increases with increasing [gas]mixture
TRUE
What are the normal values for alveolar PO2 and CO2
PO2 = 100mmHg (13.3 kPa)
PCO2 =40mmHg (5.3 kPa)
What happens to the PO2 and PCO2 during hyperventilation?
PO2 increases to 120mmHg
PCO2 falls to 20mmHg
What happens to the PO2 and PCO2 during hypoventilation?
PO2 falls to 30mmHg
PCO2 increases to 100mmHg
What cells are the alveolar walls made of?
Type I -thin walled
- cells which permit gas exchange
Type II - cells which secrete surfactant fluid
What is surfactant and describe its function
Surfactant is a detergent-like fluid produced by type II alveolar cells. This reduces the surface tension on alveolar surface membrane thus reducing the tendency for alveoli to collapse.
Why is it important to reduce surface tension?
Surface tension is the attraction of one water molecule to the other molecules. Since the alveoli is lined with fluid that is largely water-based with the water molecules arranged in a sphere around the alveoli, the attraction between these molecules causes a force that leads to the alveoli to collapse.
