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28 Cards in this Set

  • Front
  • Back
What characteristics of the lungs are involved in breathing?
1. Elastic work
2. Viscous resistance
3. Airway resistance
What is elastic work?
Stretching of elastic tissue in the chest wall and lungs by the respiratory muscles.
What components in the lungs are major determ inants of elastic forces of the lung tissue.
Elastin and collagen fibers interwoven among the lung parenchyma.
What is viscous resistance?
Moving inelastic tissues.
What percentage of O2 consumption is required with normal breathing?
What type of process is inspiration?
What muscles are involved in inspiration?
External intercostals
Acessory muscles
Which muscle contributes most to the inspiratory effort?
Movement of the diaphragm contributes app 75% of the change in intrathoracic volume during normal inspiration
Which nerve supplies the diaphragm?
The phrenic nerves, one third of their fibers are sensory to the diaphragm and 2/3 of their fibers are motor(C3, C4, and C5 keep the diaphragm alive.
What happens when the diaphragm contracts?
Volume of the thoracic cavity is increased as abdominal contents are pushed down and ribs are lifted upward and out.
When are othe rmuscles od inspiration mainly used?
What are the accessory muscles of respiration?
1. Sternocleidomastoid
2. Scalenes
3. Strap muscles of the neck.
Transsection of the spinal cord at which level results in respiratory arrest?
Above the 3rd cervical segment.
What type of process is expiration?
Which muscles are involved in active expiration?
Internal intercostals muscles and anterior abdominal wall muscles.
Whendoes active expiration occur?
Exercise and when airway resistance is increased.
Define compliance(C).
An indication of how easily the lungs and chest wall can be stretched or inflated.
What is the equation for compliance?
C= change in volume
change in pressure
What affects compliance?
Lung volume and alveolar surface tension
What process can cause a decrease in compliance?
Pulmonary congestion and interstitial pulmonary fibrosis.
How does emphysema affect compliance?
Increases it.
What is intrapleural pressure?
Pressure of the fluid in the space in between the lung pleura and the chest wall pleura.
What is the intrapleural pressure at the base of the lungs?
-2.5mm/Hg relative to atmospheric pressure.
What contributes to the intrapleural subatmospheric pressure?
The lungs passive recoil properties and the stiff chest walls tendency to expand at physiologic chest and lung volumes.
define elasticity.
The recoil force generated by distension of a structure.
What is the relationship between elastance and compliance?
What contributes to the lungs recoil properties?
Elastic tissue and surface tension.
How do LaPlaces law and surface tension affect the collapsibility of alveoli?
P= 2T

where P= collapsing presure(dyn/cm2), T = surface tension (dynes/cm), and r= alveolar radius(cm)