Test 3 Flashcards
How do we find the rate of air flow
Difference in pressure between atmosphere and intra-alveolar pressure
divided by the resistance of airways
What causes air to move into the lungs
when the pressure in the lungs is less than the pressure of the atmosphere
How does the diaphragm cause inspiration
the diaphragm contracts decreasing pressure in the thorax, causes the lungs to expand, which causes the pressure to go down, and air rushes in
How does the diaphragm affect inspiration
it relaxes, increasing pressure in the thorax, which causes the lungs to shrink, increasing pressure, forcing air out
What is boyles law
p1v1 = p2v2
The greater the pressure the less the volume
the less the volume the greater the pressure
less pressure = more volume
more volume = less pressure
How do the intercostals affect breathing
contraction leads to increased rib cage = increase volume of lungs = decrease pressure = inspiration
relaxation = decreased rib cage size = less volume in lungs = more pressure = expiration
contraction of the abdominals does what to inspiration and expiration
contraction leads to expiration, relaxation leads to inspiration.
What is pneumothorax, what happens
when air gets into the plural cavity, it gets rid of the negative intrapleural pressure in the pleural sac. so the increase in pressure there causes the lung to collapse
what is the primary way to regulate air flow into the lungs
the radius of the conducting airway
what controls the radius of the conducting airway
the autonomic nervous system
sympathetic - relaxation of smooth muscle = bronchodialation
parasympathetic = contraction of smooth muscle = bronchoconstriction
What is compliance
distensability - the ease with which lungs expand under pressure
(The lungs must be compliant for inspiration)
What is elasticity
Tendancy to return to size after being stretched
lungs must be elastic for expiration
What is it that makes the lungs elastic
the high content of elastin in the lungs
how often are the lungs under elastic tension
constantly, it increases with inspiration and decreases with expiration but it never goes away
what happens as lungs become less compliant
they become harder to expand and therefor it requires more work to inflate them
What is surfactant
A fluid secreted by the lungs that decreases the surface tension within the alveoli
Where does surfactant come from
type II alveolar cells
What is the result of surfactant decreasing the surface tension within the alveoli
it leads to increased compliance and decreased tendency to recoil
Why is it bad to not have surfactat
the lungs become really hard to inflate because of low compliance, the lungs will often collapse
What is respiratory distress syndrome
surfactant is produced late in fetal developpment, so often premature infants don’t have enough surfactant and thier lungs are hard to inflate and often collapse
What is a spirogram
The thing that measures lung volumes, inspiration and expiration
What is tidal volume TV
the amount of air inspired and expired during normal breathing (Middle portion on spirogram)
What is inspiratory reserve volume IRV
how much more you could breath in more than how much you normally do ( big peak )
What is expiratory reserve volume ERV
how much more you could breath out than you normally do. (big dip)