Resp 1 - West Ch 7 Mechanics Of Breathing

Front 1

external intercostal muscles pull ribs ____ and _____ when contracted
internal intercostal muscles pull ribs ____ and _____ when contracted

Back 1

upward and forward

downward and inward (decrease thoracic volume, stiffen intercostal spaces))

Front 2

What nerve supplies the diaphragm? Where does it originate?

Back 2

Phrenic, originates from cervical segments 3, 4, 5

Front 3

What kind of flow occurs at the trachea?
In the small airways?
Most of the bronchial tree?

Back 3

turbulent
laminar
transitional

Front 4

_____ flow is most likely to occur at high Reynolds numbers, that is when _____ forces dominate over viscous forces

Back 4

Turbulent
inertial

Front 5

Concerning the contraction of the diaphragm:
A.The nerves that are responsible emerge from the spinal cord at the level of the lower thorax..
B.It tends to flatten the diaphragm.
C.It reduces the lateral distance between the lower rib margins.
D.It causes the anterior abdominal wall to move in.
E.It raises the intrapleural pressue.

Back 5

: B. The relaxed dome state of the diaphragm flattens out.
Answer A: No! the nerves arise in the neck.
Answer C.: No! this dimension is controlled more by the intercostal muscles
Answer E: No! The intrapleural pressure falls (becomes more subatmospheric).

Front 6

Concerning the pressure-volume behavior of the lung:
A.Compliance decreases with age.
B.Filling an animal lung with saline decreases compliance.
C.Removing a lobe reduces total pulmonary compliance.
D.Absence of surfactant increases compliance.
E.In the upright lung at FRC, for a given change in intrapleural pressure, the alveoli near the base of the lung expand less than those near the apex.

Back 6

C. With a lobe missing there is less potential volume to be expanded. The remaining lung is on a less compliant portion of the curve.
Answer A: No! Age-related change in elastic properties of lung and thorax result in an increase in compliance..
Answer B: No! Filling the lung with saline removes the air-liquid interface therefore the surface tension forces, decreasing the elastic recoil and increasing the compliance.
Answer D:No! Absence of surfactant increases surface tension and therefore decreases compliance.
Answer E: No! —the opposite is true. The alveoli at the base are smaller than those at the apex and exist on a more favorable site on the compliance curve for expansion.

Front 7

Two bubbles have the same surface tension but bubble X has 3 times the diameter of bubble Y. The ratio of the pressure in bubble X to that in bubble Y is:
A. 0.3 : 1
B. 0.9 : 1
C. 1 : 1
D. 3 : 1
E. 9 : 1

Back 7

A
P is related to ST/R

Front 8

Pulmonary surfactant is produced by:
A.Alveolar macrophages.
B.Goblet cells.
C.Leukocytes.
D.Type I alveolar cells.
E.Type II alveolar cells.

Back 8

E

Front 9

The basal regions of the upright human lung are normally better ventilated than the upper regions because:
A.Airway resistance to the upper regions is higher than to the lower regions.
B.There is less surfactant in the upper regions.
C.The blood flow to the lower regions is higher.
D.The lower regions have a small resting volume and a relatively large increase in volume.
E.The PCO2 of the lower regions is relatively high.

Back 9

D. Actually due to volume and compliance (see question #2).
Answer A: There is no evidence for a difference in airway resistance between apex and base.
Answer B: There is no evidence for a difference in surfactant concentration between apex and base.
Answer C E: Statement is true but not related to the question.

Front 10

Pulmonary surfactant:
A.Increases the surface tension of the alveolar lining liquid.
B.Is secreted by type I alveolar epithelial cells.
C.Is a protein.
D.Increases the work required to expand the lung.
E.Helps to prevent transudation of fluid from the capillaries into the alveolar spaces.

Back 10

E: Surfactant decreases the alveolar fluid linings tendency to collapse (pull inward-due to surface forces) which would draw fluid from the alveolar wall interstitial space. .
Answer A No! Surfactant decreases surface tension.
Answer B No! Type II cells secrete :surfactant.
Answer C. No! Surfactant is a complex mixture of molecules.
Answer D. No! Surfactant decreases the work required to expand the lung.

Front 11

Concerning normal expiration during resting conditions:
A.Expiration is generated by expiratory muscles.
B.Alveolar pressure is less than atmospheric pressure.
C.Intrapleural pressure gradually falls (becomes more negative) during the expiration.
D.Flow velocity of the gas (in cm • sec-1) in the large airways exceeds that in the terminal bronchioles.
E.Diaphragm moves down as expiration proceeds.

Back 11

D. : Flow difference is due to the magnitude of the cross sectional area
False. During expiration the thoracic cavity is becoming smaller and the intrapleural pressure becomes less negative.
Answer A: No! Resting expiration is due to elastic recoil from energy stored during inspiration..
Answer B: No! Alveolar pressure is greater than atmospheric pressue.
Answer C No!.
Answer E: Diaphragm relaxation changes the muscle from flat to dome shaped, therefore moving toward the head.

Front 12

When a normal subject develops a spontaneous pneumothorax of his right lung you would expect the following to occur.
A.Right lung expands.
B.Chest wall on the right expands.
C.Diaphragm moves down.
D.Mediastinum may move to the left.
E.Blood flow to the right lung is reduced.

Back 12

E. The right lung is poorly ventilated, resulting in hypoxic vasoconstriction.
Answer A: No! The right pleural cavity is filled with air and the lung colapses.
Answer B: No! The elastic recoil of the lung has been removed from the chest wall, therefore the thorax will most likely expand.
Answer C. No! It is no contracting it will move up.
Answer D: The negatie intrapleural pressure on the left will draw the .mediastinum in that direction.
Answer E:

Front 13

According to Poiseuille’s Law reducing the radius of an airway to 1/3 will increase its resistance how many fold?
A. 1/3
B. 3
C. 9
D. 27
E. 81

Back 13

R = 1/r^4
1/(1/81) = 81

Front 14

Concerning airflow in the lung:
A.Flow is more likely to be turbulent in small airways than in the trachea.
B.The lower the viscosity, the less likely is turbulence to occur.
C.In pure laminar flow, halving the radius of the airway increases its resistance 8-fold.
D.For inspiration to occur, mouth pressure must be less than alveolar pressure.
E.Airway resistance increases during SCUBA diving.

Back 14

E. Diving results in compressing the respiratory gas, increasing density and viscosity with a
Answer A: In the smaller airways the flow would more likely be laminar than turbulent due to large cross sectional area and low velocity.
Answer B: Turbulance is more likely at low viscosity. See calculation of the Rupra’s number.
Answer C: It is r to the 4th power—to be correct the relationship would be 16 fold.
Answer D: The opposite must be true.

Front 15

The most important factor limiting flow rate during most of a forced expiration from total lung capacity is:
A.Rate of contraction of expiratory muscles.
B.Action of diaphragm.
C.Constriction of bronchial smooth muscle.
D.Elasticity of chest wall.
E.Compression of airways.

Back 15

E. The dynamic compression of airways cannot be overcome by A, B, or D
Answer C: Under normal conditions there is no bronchial constriction.

Front 16

Which of the following factors increase the resistance of the airways:
A.increasing lung volume above FRC.
B.Increased sympathetic stimulation of airway smooth muscle.
C.Diving to high altitude.
D.Inhaling cigarette smoke.
E.Breathing a mixture of 21% O2 and 79% Helium (molecular weight 4).

Back 16

D. : Smoke is a local irritant causing bronchoconstriction .
Answer A: No! Results in increased airway diameter and decreased air flow resistance..
Answer B: No! Sympathetic stimulation causes bronchodilatation.
Answer C: No! Altitude results in a decrease in density of respiratory gas and a decrease in airway resistance..
Answer E: No! The new added gas results in an decrease in density.

Front 17

A normal subject makes an inspiratory effort against a closed airway. You would expect the following to occur.
A.Tension in the diaphragm decreases.
B.The internal intercostal muscles become active.
C.Intrapleural pressure increases (becomes less negative).
D.Alveolar pressure falls more than intrapleural pressure.
E.Pressure inside the pulmonary capillaries falls.

Back 17

E. True—decreased resistance in the intra and most likely the extra-alveolar vessels due to the decrease in alveolar pressure.
Answer A: No!—the diaphragm is contracting.
Answer B. No! –the external intercostal muscles become active.
Answer C: No! – the intrapleural pressue will move more toward the negative side due to expansion of the thorax.
Answer D.: No! Since this is a closed system, the alveolar pressure changes must parallel the intrapleural pressure change.

Front 18

In general, the lung is very compliant (200ml/cm H20), but it becomes stiffer with less compliance when?

Back 18

At high expanding pressures
Pulmonary fibrosis
Alveolar edema
Collapse (unventilated for a period)
High pulmonary venous pressure (engorged w/ blood)

Front 19

What is the equation for compliance?

Back 19

Delta V/ Delta P - it is the slope of the pressure/volume curve

Front 20

What is Laplace's law that describes pressure due to surface tension?

Back 20

P = 4T/r

Front 21

Physiological advantages of surfactant:
1) low surface tension in alveoli increases _____ of the lung and reduces ______ of expanding it with each breath
2) Stability by making surface tension a function of ____
3) Help keep alveoli ____

Back 21

compliance
work
area (so small alveoli don't have higher pressure and are not forced to turn into one giant one)
Dry - surface tension forces tend to collapse alveoli and suck fluid into alveolar spaces from capillaries

Front 22

Because of the _____ of the lung, intrapleural pressure is less _____ at the base than at the apex. As a consequence, the basal lung is relatively _____ in its resting state but _____ more on inspiration than the apex

Back 22

weight
negative
compressed
expands

Front 23

At equilibrium, the forces of the chest wall and lung are balanced how?
What is the volume of the lung at this point?

Back 23

Chest wall is pulled inward and lungs are pulled outward - reach equilibrium
Functual residual capacity

Front 24

Zero pressure of the lung is at its minimal volume which is below _____ volume
Chest equilibrium is at ___% of vital capacity where the chest no longer wants to spring out

Back 24

residual
75%

Front 25

Resistance to flow in ______ systems is usually linearally related to the pressure
In ______ flow systems it is related to the square of the velocity

Back 25

laminar
turbulent (MORE resistant - takes more work to push gas through)

Front 26

Where is the chief site of airway resistance?
What is the significance of this?

Back 26

intermediate sized bronchi
Relatively little reisistance (less than 20%) is in the small airways - this is due to the large number of small airways in the periphery

Front 27

Like the extra-alveolar blood vessels, the bronchi are supported by the _____ traction of parenchyma and their caliber is ______ as the lung expands

Back 27

radial
increased

Front 28

As lung volume is reduced, airways resistance _____ rapidly.

Back 28

rises

Front 29

Dynamic compression of airways limits air flow in normal subjects during a ____ ______, and in a diseased lung at low ______ flow rates - thus reducing excerise ability

Back 29

forced expiration

expiratory

Front 30

During dynamic compression flow is determined by ______ pressure minus ______ pressure (NOT _____ pressure)

Back 30

alveolar
pleural

mouth

Front 31

How do people with severe airway obstruction breathe?How do people with reduced compliance (stiff lungs) breathe?

Back 31

Purse lips so maximum resistance is at the outside so airway stays open. Also breathe slowly to not add more pressure (low turbulence)

shallow with high frequency of breaths

Both reduce the work done on the lungs

Front 32

Both decreased compliance of the lungs and increased airway resistance result in abnormally low ______

Back 32

volume (inspired volume)

Uneven ventilation results

Front 33

The higher the breathing rate, the faster the flow rates and the larger the ______ work area.
The larger the tidal volume, the larger the ____ work area.

Back 33

viscous (air work)
elastic