Lung mechanics

Question 1

List 4 main lung functions:

Answer 1

oxygenation, ventilation, blood filtration, and drug metabolism.

Question 2

What’s the correct order from inner most to the outside most for the following: Parietal pleura, lung, pleural space, chest wall, visceral pleura?

Answer 2

Lung, visceral pleura, pleural space, parietal pleura, chest wall.

Question 3

During inspiration, the 12 pairs of ribs move___; the diaphragm ____ and moves____

Answer 3

Upward and forward; contracts, downward

Question 4

If we expand the lung too much, we have to compromise other things in the chest cavity, which include___

Answer 4

blood, fluid, major vessels, and the heart

Question 5

The natural holes in the diaphragm are the places where hernia can develop. Y/N?

Answer 5

Y

Question 6

If one side gets pneumothorax, the other side of the lung can still be ventilated. Y/N?

Answer 6

Y

Question 7

The lung and chest wall can be modeled as springs or elastic bands which get stretched during inspiration and recoil when the muscles relax during expiration. The force required to stretch a spring depends on its basic properties and is generally linear over a wide range.Y/N?

Answer 7

Y

Question 8

What’s elasticity?

Answer 8

The property by virtue of which an object resists and recovers from deformation produced by force. E = ΔPressure/ΔVolume = cmH20/liter

Question 9

What’s compliance?

Answer 9

The reciprocal of elasticity and is the deformation per unit force applied. C = ΔVolume/ΔPressure = liter/cmH20

Question 10

What do Type I (Squamous Alveolar) cells do?

Answer 10

Form the structure of an alveolar wall

Question 11

What do Type II (Great Alveolar) cells do?

Answer 11

Secrete pulmonary surfactant to lower the surface tension of water and allows the membrane to separate, therefore increasing its capability to exchange gases.

Question 12

Type II cells are bigger than Type I cells. Y/N?

Answer 12

Y

Question 13

Premature babies have problems producing surfactant. Y/N?

Answer 13

Y

Question 14

What do Macrophages do?

Answer 14

Destroy foreign material, such as bacteria

Question 15

Where in the airway tree does it have smooth muscle that can constrict and dilate?

Answer 15

Terminal bronchi

Question 16

What’s respiration?

Answer 16

Cellular level process metabolizing food and releasing ATP and CO2.

Question 17

What’s ventilation?

Answer 17

Expanding lungs and exchanging air in the alveoli

Question 18

The elastic recoil of the lung reflects which two major components?

Answer 18

Tissue elasticity - the lung tissue contains elastin, collagen and other components which stretch and recoil when released.
Surface tension - surface forces exist at any gas liquid interface such as we have in the alveoli

Question 19

What does the Laplace’s Law states?

Answer 19

that pressure is inversely proportional to alveolar radius, and directly proportional to surface tension. If the surface tensions are equal, a small alveolus will experience a greater inward pressure than a large alveolus. In that case, if both alveoli are connected to the same airway, the small alveolus will be more likely to collapse, expelling its contents into the large alveolus.

Question 20

Surfactant reduces the surface tension on all alveoli, but its effect is greater on small alveoli than on large alveoli. Thus, surfactant compensates for the size differences between alveoli, and ensures that smaller alveoli do not collapse. Y/N?

Answer 20

Y

Question 21

When the respiratory muscles are relaxed the volume of gas left in the lungs is determined by the balance of inward force of the lung and the outward force of the chest wall. What is this volume called?

Answer 21

FRC

Question 22

At high lung volumes both the lung and chest wall tend to recoil inward. Y/N?

Answer 22

Y