Mechanism of Breathing/Compliance Flashcards Preview

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Flashcards in Mechanism of Breathing/Compliance Deck (22):
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Steps in inspiration

1) contraction of inspiratory muscles

2) inflation of chest cavity

3) inflation of lung

4) inward airflow

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What are inspiratory muscles?

Mechanism (image)

Diaphragm

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External intercostals - muscle of ____

mechanism image

inspiration

contraction of intercostals --> expands rib cage

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when are your expiratory muscles active?

during forced expiration and exercise (abd wall muscles)

NONE ACTIVE DURING QUIET BREATHING

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Patients with obstructive diseases breathe at ___

higher lung volumes

average lung size with breathing is larger in obstructive disease

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resting diaphragm after expiration is ____ (more or less contracted) than average inflated lung

therefore, diaphragm is (shorter/longer)

more contracted

diaphragm is shorter

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what is intrapleural pressure?

what happens to PIP when you inspire?

pressure between chest wall and lung

negative PIP (vacuum) causes lung to attach to chest wall

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equilibrium size of lung is (larger/smaller) than in body

smaller

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2 opposing forces that cause lung to inflate

1) chest wall tends to inflate
2) lung tends to deflate

--> negative intrapleural pressuere

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Typical values of PIP

@ end of expiration

@ end of inspiration

-5 cm-H2O

-30 cm-H2O

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What happens in pneumothorax

bullet disrupts hydraulic connection between lung and chest wall

PIP less negative

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How does Plung change with inspiration and expiration (graph)

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Definition of lung compliance

which is worse, low or high compliance

graph of compliance curve

measure of how easily applied pressure induces a volume change

low compliance b/c requires more pressure for a given volume change

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why does PTP incr?

use equation

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Hysteresis curves for inspiration vs. expiration

difference in compliance d/t additional energy required during inspiration to recruit and inflate additional alveoli

Lung volume at any given pressure during inhalation is less than the lung volume at any given pressure during exhalation

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how does emphysema vs. restrictive disease affect the lung volume vs. PTP curve

emphysema = incr compliance = destroy elastin

restrictive disease = more rigid = harder to inflate

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how does emphysema affect P lung during epiration

P lung is less positive b/c lose recoil strength so no gradient for outward air flow

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Causes of reduced chest wall compliance

what does curve look like?

1) old age - more fibrotic tissue in rib cage

2) obesity - extra fat impedes outward movement of chest wall

3) scar tissue

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how does reduced chest wall complaince affect tidal volume?

decr tidal volume