"Medical Physiology Pulmonary Mechanics II Amit S. Dhamoon" SANA Flashcards

1
Q

Why does the compliance decrease at very high lung volumes?

A

As the lung fills up more, it is less able to stretch

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2
Q

What is hysteresis?

A

The biophysical observation that the volume/pressure curve is different for inflation and deflation of the lungs

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3
Q

If you remove all water from a lung and fill it in with saline instead, what will happen to the compliance?

A

The compliance will increased

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4
Q

If you remove all water from a lung and fill it in with saline instead, will hysteresis be observed?

A

No

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5
Q

What is the function of surfactant?

A

Decreased surface tension

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6
Q

A premature infant is born with infant respiratory distress. If saline is administered into the infant’s lungs, what will happen to the compliance?

A

Because the baby is born without surfactant, the compliance of the lung is very low. The saline will increase the compliance.

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7
Q

Your geriatric patient comes in with a collapsed lung. How compliant is his lung at this point? Why?

A

Very un-compliant, making it harder to ventilate since surfactant production goes down in a collapsed lung.

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8
Q

In cases of pneumothorax, the intrapleural pressure is ____ and the alveolar pressure is ____

A

both 0

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9
Q

Name one disease in which the lung is TOO compliant?

A

Emphysema

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10
Q

Which of the following stages of breathing is most difficult for an emphysema patient?

a. inhalation
b. exhalation

A

exhalation is more difficult as the lung compliance is too high due to elasticity being lost, leading to air being trapped in the lungs.

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11
Q

According to LaPlace’s law, if two bubbles of different sizes have the same surface tension, which one will have a larger internal pressure?

A

smaller bubble

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12
Q

The lung has alveoli in various sizes. What is keeping the smaller alveoli from emptying into the larger ones, as would be predicted by LaPlace’s law since smaller alveoli have higher internal pressures?

A

The surfactant reduces the surface tension of the alveoli. Because it is less concentrated on the surface of the larger alveoli (which have greater radius), and more concentrated on smaller alveoli, the surface tensions balance out between the two different sizes, causing them to be stable.

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13
Q

What is the functional residual capacity (FRC)?

A

The FRC represents the equilibrium between the chest wall and the lungs, when the outward recoil force of the chest is equal to the inward recoil force of the lungs.

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14
Q

How can you change your residual volume?

A

You can’t, that’s the air that’s still in your lungs once you have expired as much as you can. There will always be some air left in your lungs.

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15
Q

What does the FRC represent in terms of the stages of breathing?

A

It is the point when you’re getting ready to take another breath

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16
Q

Which of the follow is a correct representation of vital capacity?

a. Functional residual capacity + tidal volume
b. tidal volume + inspiratory reserve volume + expiratory reserve volume
c. inspiratory reserve volume + expiratory reserve volume

A

b.

17
Q

Which of the follow is a correct representation of functional residual capacity?

a. inspiratory reserve volume + tidal volume
b. tidal volume + inspiratory reserve volume + expiratory reserve volume
c. residual volume + expiratory reserve volume

A

c

18
Q

How is compliance measured with a spirometer?

A

An esophageal balloon is swallowed and the patient will breath in and then hold breath with glottis open, relaxing all the chest muscles against the weighted spirometer. The spirometer will then be able to measure the recoil force of the lungs and chest wall after the breath that was just taken.

19
Q

What is the total transmural lung pressure at FRC?

A

0 (at equilibrium), when the total system pressure is crossing 0, that’s the FRC.

20
Q

Just like a spring, if you expand the chest wall to a greater size, it will:

a. want to recoil to become smaller and its pressure will become more positive.
b. want to expand more and its pressure will become more positive
c. want to recoil to become smaller and its pressure will be more negative
d. want to expand more and its pressure will become more negative

A

a.

21
Q

If the total pressure of the system is moving to the right of the 0 line of the vital capacity/pressure curve, the lung is ________ (inflating/deflating)

A

inflating

22
Q

If the total pressure of the system is moving to the left of the 0 line of the vital capacity/pressure curve, the lung is ________ (inflating/deflating)

A

deflating

23
Q

According to the vital capacity/pressure graph, at very high lung capacity, both the chest wall and the lung will have an _______(inward/outward) elastic recoil.

A

inward.

24
Q

According to the vital capacity/pressure graph, at very low lung volume, the chest wall will have an ______ (inward/outward) recoil and the lung will have an _______(inward/outward) elastic recoil.

A

chestwall: outward
lungs: inward

25
Q

What is the difference in chest wall and lung recoil during high lung volume and low lung volume?

A

During high lung volume, both of them will have an inward recoil. During low lung volumes, chest wall will have outward recoil and lungs will have an inward recoil.

26
Q

Inpiration takes _________ (longer/shorter) time than expiration.

A

shorter time

27
Q

In emphysema and obstructive lung disease, what happens to the inspiration/expiration ratio?

A

It decreases as expiration is prolonged due to high compliance of lungs

28
Q

During a normal breath there are two points where there is no flow. What are they?

A

End of inspiration and end of expiration

29
Q

During a normal breath when is lung volume highest?

A

End of inspiration