Pulmonary Mechanisms II

Question 0

What takes up more time in the respiration cycle….inhalation or exhalation?

Answer 0

Exhalation takes longer

Question 1

When you inhale, does Ppl increase or decrease?

Answer 1

It decreases (becomes more negative)

Question 2

Explain the shape of the flow and Palv curves for the dynamics of breathing

Answer 2

The shape of the curves are identical. Flow parallels Palv.

Question 3

Why does the volume of the lung increase?

Answer 3

Because of an increase in transmutation pressure

Question 4

What does maximum floe correspond to?

Answer 4

Minimum Palv at mid-inspiration and maximum Palv at mid-expiration

Question 5

What sets the lung volume?

Answer 5

Transmutes pressure across the lung

Question 6

When does Ppl reach a minimum?

Answer 6

End of inspiration

Question 7

1 mm Hg= ?

Answer 7

1.36cm

Question 8

What is FRC?

Answer 8

The lung volume when Pt equals zero

Question 9

When is the lung at FRC?

Answer 9

At the end expiratory position

Question 10

At FRC, Pc= ?

Answer 10

Pc= Pl

Question 11

At what percent vital capacity does the mechanical equilibrium position fall?

Answer 11

It falls at 36% vital capacity

Question 12

At volumes below the FRC, what force provides the dominant driving force for the lung to return back to FRC?

Answer 12

The expansive force of the chest wall

Question 13

What does normal functioning of the lung depend on?

Answer 13

The proper passive elastic properties of the lung and chest wall

Question 14

What is static compliance?

Answer 14

This determines what particular volume the lung and chest wall will assume for a given tans mural pressure when the elastic vessels are at mechanical equilibrium with no moving air

Question 15

How is compliance estimated ?

Answer 15

From the inverse slope of a pressure-volume curve

Question 16

When a weight is placed on a spirometer that is in used, what values increase and what values decrease?

Answer 16

The change in Palv will increase, the change in Vlung will increase, and the change in Vsp will decrease

Question 17

Why does Ppl increase during measurement of chest wall compliance with a spirometer?

Answer 17

It increases because chest muscles are relaxed against a weighted spirometer

Question 18

What is dynamic compliance?

Answer 18

An attempt to measure the lung compliance during breathing.

Question 19

What does an decrease in dynamic compliance indicate?

Answer 19

it indicates increased airway resistance

Question 20

How is dynamic compliance obtained?

Answer 20

It is obtained from changes in pressure and volume for both end inspiration and end expiration

Question 21

When will dynamic compliance agree with static compliance?

Answer 21

If equilibrium is attained at end inspiration and end expiration

Question 22

In a normal individual, does Dynamic compliance change much from breath do breath?

Answer 22

No it does not

Question 23

Why does the ideal laminar flow equation only give limited qualitative appreciation of the relative importance of a few variables that affect airway resistance?

Answer 23

Because airways are not rigid tubes with uniform diameter, but are dispensable and compressible branching tubes with irregular bores

Question 24

Where is flow laminar? Where is is turbulent?

Answer 24

At is laminar at the trachea but turbulent at each bifurcation

Question 25

What is the breakdown of resistance to breathing?

Answer 25

Tissue resistance= 20%

Airway resistance= 80%

Question 26

What is the breakdown of airway resistance?

Answer 26

Small airways= 10%
Trachea and bronchi=15%
Glottis= 25%
Nose or mouth= 50%

Question 27

In bronchitis, what is a main site of resistance, that is not normally a major player?

Answer 27

Bronchioles

Question 28

When is frictional resistance present?

Answer 28

Only during motion (of air)

Question 29

Why does resistance decrease in the small airways?

Answer 29

Because of all the parallel pathways (increase of cross sectional area)

Question 30

Resistance ___________ as lung volume ____________.

Answer 30

Decreases

Increases

Question 31

Does epinephrine increase or decrease airway resistance?

Answer 31

Decrease

Question 32

Explain the mechanism of how epinephrine decreases airway resistance

Answer 32

1- epi binds with high affinity to beta 2 receptors
2- increase in cAMP
3- protein kinase A is stimulated
4- PKA phosphorylation myosin light chain kinase
5- decreases sensitivity to MLCK for Ca- Calmodulin
6- inhibited binding of myosin CRO’s bridges to actin
7- dilated bronchi and bronchioles result and resistance is reduced
8- beating is enhanced

Question 33

Is there neural innervation of bronchial smooth muscle?

Answer 33

Yes, but it is sparse

Question 34

How are bronchial smooth muscles dilated?

Answer 34

Epinephrine acting on beta 2 receptors

Question 35

How are bronchial smooth muscles contracted?

Answer 35

Through the vagus nerve (Ach) on M receptors

Question 36

Does histamine bronchoconstrict or brochodilate?

Answer 36

It bronchiconstricts

Question 37

What increases resistance in asthma?

Answer 37

Inflammatory swelling of bronchial mucosa

Question 38

What is PEEP?

Answer 38

Positive end-expiratory pressure

Question 39

Does PEEP increase or decrease in patients on ventilators?

Answer 39

It decreases

Question 40

How are IVPF curves constructed?

Answer 40

They are constructed from simultaneous measurements of flow rates, lung volumes and alveolar pressures during a series of forced expirations, each more rapid and vigorous than the preceding one until maximal effort is made

Question 41

What do IVPF curves show?

Answer 41

At low volumes, increasing the driving pressures leads to a maximal flow rate and that the maximal flow rate increases lung volumes