Respiration Physiology Part 3 Flashcards
What are the two kinds of resistance to ventilation?
> elastic resistance
• non-elastic resistance
What is Compliance?
ability of an elastic structure to resist
stretching or distortion
What causes compliance?
Results from the elastic recoil of the lungs and chest
• Comprises 70% of the total resistance to ventilation
What is Compliance of the lung?
•the expandability of elastic tissues when acted on by
foreign forces
• ability of lung to stretch
What is the formula for compliance?
C=AV/AP (ДР: transpulmonary pressure)
• The larger the compliance….
the less elastic resistance
What is lung compliance the measure of?
The lung’s Stretchability
What might happen when lung compliance is abnormally high?
the lungs might fail to hold themselves open, and are prone
to collapse.
What might happen when lung compliance is abnormally low?
The work of breathing is increased
What does the pressure volume curve reflect?
Reflects changes of the lung compliance or elastic resistance
relative to altered volume of the lung
Lung compliance in normal breathing at rest is?
approximately
0.2L/cm H20
What is the formula for measuring specific compliance of the lung?
compliance=lung compliance measured in normal resting
breathing (L/cmH20) / functional residual capacity of the lung (L)
What is specific compliance ? And what is it’s function?
Specific compliance is the compliance per unit volume and is used
to compare the lung elastic resistance of individuals
When injected the same amount of air, the lung with larger total capacity expands to a less extent, the elastic resistance of the lung
would be smaller, suggesting?
Less compliance
elastic resistance is due to:
Surface tension of alveolar fluid (213)
• Elasticity of lungs & thoracic wall (1/3)
What does surface tension do?
pulls fluids together, that it could cause an alveolus to buckle
What is Laplace’s law?
P=2T/radius
What is a surfactant?
A fluid material that
decreases surface tension
What secretes surfactant ?
type Il alveolar cells
What do surfactants contain?
mixture of lipoproteins ( DPPC) and surfactant-
associated protein
What are the Physiological effects of surfactant?
Its density is inversely proportional to the radii of the alveoli
• reduces surface tension
• Reduces respiratory resistance (increases compliance)
• Maintains the stability of the alveoli
• keeps the dryness of the alveoli
What is Newborn respiratory distress syndrome?
retraction of soft tissue on inspiration (“seesaw”)
Characterized by cyanosis
What causes Newborn Respiratory distress Syndrome?
Inadequate surfactant
What does non elastic resistance include?
airway resistance(80-90%)
•inertial resistance
• viscous resistance
What causes airway resistance?
friction among gas molecules and between gas molecules and the inner way of airway; distributed in nose, glottis, trachea and bronchia and
bronchioles
What is the formula for airway resistance?
F= (Palv- Patm)/R
• R=1/r4
What affects airway radii?
physical (transpulmonary pressure; elastic connective tissue fibers), neural
(sympathetic & parasympathetic) and chemical factors
What are pulmonary volumes ?
measurements of the subdivisions of the air in the lungs
What are pulmonary capacities?
Combinations of divisions
What are the 4 pulmonary volumes?
• Tidal Volume
•Inspiratory Reserve Volume
•Expiratory Reserve Volume
• Residual Volume
What are the types of pulmonary capacities?
• Vital Capacity
•Inspiratory Capacity
•Functional Residual Capacity
• Total Lung Capacity
