Chapter 13 Flashcards
______ initiates inspiration.
contraction of diaphragm and the external intercostal muscles
As thoracic wall moves farther away from _______(lung surface), the intrapleural pressure becomes _______. The decrease in intrapleural pressure increases __________?
visceral pleura
more subatmospheric (decrease in pressure)
transpulmonary pressure
P(ip), and also known as?
pressure surround the lungs, intrapleural fluid pressure
Following the increase in transpulmonary pressure, the ______(s) expand. This expansion is a result of what?
lungs expand. the expansion of the thorax reduces alveolar pressure P(alv) below atmospheric pressure P(atm), so air moves into the lungs - and therefore into alveoli
Expiration causes reduction in the size of the _______. This immediately makes the ________ pressure less ________. Aka the P(ip) ________. This in turn decreases the _______ pressure.
- thoracic cage
- intrapleural fluid pressure less subatmospheric (aka the Pip increases)
- This causes a decrease in the transpulmonary pressure P(tp)
After transpulmonary pressure is decreased during expiration, the lungs recoil. This does what to the air in alveoli? This causes the P(alv) to be ________ than the P(atm).
- the air in the alveoli becomes compressed
- this causes the pressure in the alveoli to become greater than the pressure in the atm and air moves out of the lungs
What is compliance?
Lung compliance is the magnitude of the change in lung volume produced by a given change in the transpulmonary pressure. AKA it is how easy we can bring air into the lungs. Measure of the lungs “stretchability”
What conditions cause increased compliance?
emphysema or COPD
What is elastance?
the tendency to return to initial size after distension with aid from elastin proteins. AKA how easy it is to get the air out of the lungs.
Pulmonary surfactant is a mixture of what?
phospholipids and protein
what cells secrete surfactant?
type II alveolar cells
surfactant lowers what? this in turn increases what?
surfactant lowers surface tension at the surface of the alveoli, which increases compliance - aiding the lungs in easier expansion during inhalation
as an alveolus gets smaller, the molecules of surfactant on its inside surface are what? thus this does what?
less spread out, which reduces surface tension
machine that measures lung capacity for air
spirometer
P(tp)
transpulmonary pressure - the pressure difference between the lungs and the atmosphere (inside and outside of the lungs)
500mL is normal for what?
resting tidal volume (TV)
What is tidal volume?
TV is the amount of air inhaled or exhaled in one breath during relaxed, quiet breathing
volume of air we can move in over the tidal volume? what does this help with? number here?
IRV - inspiratory reserve volume. this helps with exercise. is about 3,000mL in excess of the tidal inspiration (so 6x the greater than resting tidal volume)
volume of air we can move out over the tidal volume. number here?
expiratory reserve volume (ERV) - 1,200mL in excess of tidal expiration
amount of air remaining in the lungs after maximum expiration; keeps alveoli inflated b/w breaths and mixes with fresh air on next inspiration
residual volume (RV)
Total lung capacity?
reserve volume + expiratory reserve volume + inspiratory residual volume + tidal volume = 6L usually but there is some variation
Amount of air remaining in the lungs after normal tidal expiration. What’s the equation?
Functional residual capacity (FRC) – RV + ERV = 2400mL
the maximal volume of air a person can expire after a maximal inspiration. what is the equation?
vital capacity - TV + ERV + IRV
FEV1 - what’s the protocol for this test?
Forced expiratory volume in one second
-take a deep breath –> tidal volume + IRV and then exhale very fast and they will measure the amount of air you got out in one second
