Respiratory Mechanics II And III Flashcards
What are 4 characteristics of respiratory skeletal muscles
1) Most used skeletal muscles
2) Only skeletal muscles necessary for life
3) Under both involuntary and voluntary control
4) Do not work to overcome inertia, and instead elastic (costal cartilages, lung parenchyma) and resistive (airway resistance, tissue viscosity) loads
Amount of force produced by respiratory muscles is determined by what 2 things:
1) Force-length relationship: Length of muscle when its contracted
2) Force-velocity relationship: How fast muscle needs to contract
What are the 2 components of total muscle force?
1) Active muscle contraction
2) Passive stretch of elastic components
Describe 3 characteristics of the length-tension curve of a muscle
1) Maximum active tension is generated at resting length
2) Passive tension increases exponentially beyond resting length
3) Total muscle forces increases in a lengthened position because passive tension compensates for loss of active tension as the length of the muscle increases
Describe this image in regards to active tension
1) Increased overlap
2) Overlap is optimal
3) Reduced overlap
4) Almost no overlap
**Muscles cannot produce as much active tension when in a shortened or lengthened position due to loss of optimal overlap
Describe the force-length relationship in the diaphragm and how it is different from regular skeletal muscle
Diaphragm can generate more active tension than limb skeletal muscle to generate force
Describe how radius curvature impacts the diaphragm
If we increase the radius and the tension stays the same then the pressure will decrease. Therefore a more flattened diaphragm will generate less pressure (force).
**Look at Laplace’s law formula in picture
List 5 important characteristics about the length of the diaphragm
1) Length of diaphragm is most important determinant of contractile force
2) The diaphragm generates more force when more sharply curved
3) If the diaphragm is higher in the thorax it has an increased curvature and length
4) If the diaphragm is lower in the thorax it has a decreased curvature and length
5) The diaphragm can generate active tension over a broad range of lengths
Terminology: Force (skeletal muscles) means what in respiratory muscles
Pressure (force/surface area)
Terminology: Length (skeletal muscles) means what in respiratory muscles
Lung volume (overall change in muscle length)
Terminology: Velocity (skeletal muscles) means what in respiratory muscles
Air flow ( overall volume/overall time)
Describe the volume-pressure (Force-length) relationship of the lungs
1) Increases in lung volume towards total lung capacity results in inspiratory muscles to shorten (agonists) and expiratory muscles to lengthen (antagonists) -> expiratory muscles generate maximum pressure at total lung capacity
2) Decreases in lung volume towards residual volume results in expiratory muscles to shorten (agonists) and inspiratory muscles to lengthen (antagonists) -> inspiratory muscles generate maximum pressure at residual volume
Coughing is produced by
Forceful contraction of expiratory muscles
When teaching a patient how to cough, what is the first step to maximize force (pressure)?
Since expiratory muscles generate max pressure at total lung capacity, we want the patient to take a deep breath in to produce the strongest cough
An [increase/decrease] in velocity = an [increase/decrease] in force (muscle)
Increase in velocity = decrease in force
Describe the maximum pressure (force) if respiratory muscles in terms of velocity
As max pressure of respiratory muscles decreases, the velocity flow increases.