Ch 7 Mechanics Part 3

Question 1

What is the primary function of β1 receptors?

Answer 1

They occur principally in the heart.

Question 2

What do β2 receptors relax?

Answer 2

Smooth muscle in the bronchi, blood vessels, and uterus.

Question 3

What are selective β2-adrenergic agonists used for?

Answer 3

Treatments of asthma and chronic obstructive pulmonary disease (COPD).

Question 4

What effect does parasympathetic activity have on the bronchi?

Answer 4

Causes bronchoconstriction.

Question 5

What does a fall in Pco2 in alveolar gas do?

Answer 5

Causes an increase in airway resistance.

Question 6

What does the injection of histamine into the pulmonary artery cause?

Answer 6

Constriction of smooth muscle located in the alveolar ducts.

Question 7

What type of agents are used in COPD?

Answer 7

Anticholinergic agents.

Question 8

What factors affect airway resistance?

Answer 8

• Density of inspired gas
• Viscosity of inspired gas

Question 9

How does lung volume affect airway resistance?

Answer 9

Airway resistance decreases as lung volume rises.

Question 10

What is the main site of airway resistance?

Answer 10

Medium-sized bronchi.

Question 11

What happens to resistance during a deep dive?

Answer 11

Resistance increases due to increased gas density.

Question 12

What is the relationship between flow and airway resistance in medium-sized airways?

Answer 12

Flow is not purely laminar.

Question 13

What is dynamic compression of airways?

Answer 13

A phenomenon where flow becomes effort-independent during forced expiration.

Question 14

What is FEV1.0?

Answer 14

Forced expiratory volume in the first second.

Question 15

What is FVC?

Answer 15

Forced vital capacity.

Question 16

What is the normal FEV1.0 percentage of FVC?

Answer 16

Approximately 80%.

Question 17

In restrictive diseases, how are FEV1.0 and FVC affected?

Answer 17

Both are reduced, but FEV1.0/FVC% is normal or increased.

Question 18

In obstructive diseases, how does FEV1.0 compare to FVC?

Answer 18

FEV1.0 is reduced much more than FVC, giving a low FEV1.0/FVC%.

Question 19

What does FEF25%–75% measure?

Answer 19

Average flow rate over the middle half of expiration.

Question 20

What is a key factor in the cause of uneven ventilation?

Answer 20

Compliance of the lung units and resistance of the airways.

Question 21

What defines a lung unit with a long time constant?

Answer 21

The product of compliance and resistance.

Question 22

What is tissue resistance?

Answer 22

The pressure required to overcome viscous forces within the lung and chest wall.

Question 23

What percentage of total resistance is tissue resistance in young normal subjects?

Answer 23

About 20%.

Question 24

What is the work of breathing measured as?

Answer 24

Pressure × volume.

Question 25

What does the area under the pressure-volume curve during inspiration represent?

Answer 25

The work done on the lung.

Question 26

What does the work done on expiration primarily overcome?

Answer 26

Airway and tissue resistance.

Question 27

How does increased airway resistance affect intrapleural pressure during inspiration?

Answer 27

It makes the intrapleural pressure more negative, increasing work.

Question 28

What happens to maximal flow as lung volume decreases?

Answer 28

Maximal flow decreases due to reduced alveolar-intrapleural pressure.

Question 29

What limits airflow during forced expiration in normal subjects?

Answer 29

Dynamic compression of airways.

Question 30

What condition can exaggerate the flow-limiting mechanism during expiration?

Answer 30

Increased resistance of the peripheral airways.

Question 31

In patients with severe lung disease, when can flow limitation occur?

Answer 31

During normal breathing expirations.

Question 32

What is the work required to overcome airway (+ tissue) resistance during expiration called?

Answer 32

AECFA ## Footnote This area represents the work done during expiration in the pressure-volume curve.

Question 33

What does the area 0AECD0 represent in the lung pressure-volume curve?

Answer 33

Elastic work ## Footnote This area indicates the work done to overcome elastic forces during lung inflation.

Question 34

What happens to the work dissipated as heat during expiration?

Answer 34

It is represented by the difference between areas AECFA and 0AECD0.

Question 35

How does increased breathing rate affect the work done on the lungs?

Answer 35

It increases the viscous work area ABCEA.

Question 36

What is the relationship between tidal volume and elastic work area?

Answer 36

A larger tidal volume results in a larger elastic work area 0AECD0.

Question 37

What is the primary muscle of respiration?

Answer 37

Diaphragm.

Question 38

Is inspiration active or passive?

Answer 38

Active.

Question 39

Is expiration during rest active or passive?

Answer 39

Passive.

Question 40

What is the efficiency percentage of the work done in breathing?

Answer 40

5% to 10%.

Question 41

What is the O2 cost of quiet breathing compared to total resting O2 consumption?

Answer 41

Less than 5%.

Question 42

What happens to the O2 cost of breathing during voluntary hyperventilation?

Answer 42

It can increase to 30%.

Question 43

What happens to lung compliance in premature babies with an immature surfactant system?

Answer 43

Lung has low compliance and is unstable and edematous.

Question 44

What does the chest wall do at functional residual capacity (FRC)?

Answer 44

Expands outward.

Question 45

In laminar flow, how is resistance related to the radius?

Answer 45

Inversely proportional to the fourth power of the radius.

Question 46

How does lung volume affect airway resistance?

Answer 46

Lung airway resistance is reduced by increasing lung volume.

Question 47

What effect do β2-adrenergic agonists have on airway resistance?

Answer 47

They reduce resistance.

Question 48

What is dynamic compression of the airways during forced expiration?

Answer 48

Flow that is effort independent.

Question 49

What is the driving pressure during dynamic compression?

Answer 49

Alveolar minus intrapleural pressure.

Question 50

What respiratory pattern do patients with reduced compliance tend to exhibit?

Answer 50

Small rapid breaths.

Question 51

What respiratory pattern do patients with severe airway obstruction tend to exhibit?

Answer 51

Slow breathing.

Question 52

What happens to the right lung during a spontaneous pneumothorax?

Answer 52

It contracts.

Question 53

What does pulmonary surfactant help prevent?

Answer 53

Transudation of fluid from capillaries into alveolar spaces.

Question 54

What is the expected effect of a reduced airway diameter on resistance?

Answer 54

Resistance increases significantly.

Question 55

What is the effect of surfactant absence on lung compliance?

Answer 55

Increases compliance.

Question 56

What happens to intrapleural pressure during expiration?

Answer 56

Gradually becomes more negative.

Question 57

What happens to the alveolar pressure during normal expiration?

Answer 57

It is less than atmospheric pressure.

Question 58

What happens to the diaphragm during normal expiration?

Answer 58

It moves up.

Question 59

What is the relationship between airflow and lung resistance?

Answer 59

Airway resistance increases with decreasing lung volume.

Question 60

What is Poiseuille’s law regarding airway radius and resistance?

Answer 60

Reducing the radius to one-third increases resistance 81-fold.

Question 61

What is the relationship between flow rate and forced expiration in patients with obstructive lung disease?

Answer 61

The flow rate is limited during expiration.

Question 62

What happens to the peak expiratory flow when a subject exhales with maximum effort?

Answer 62

It increases.

Question 63

How does increased airway mucus production affect airway resistance?

Answer 63

It increases resistance.

Question 64

What is the most important factor limiting flow rate during forced expiration?

Answer 64

Compression of airways.

Question 65

What is the expected change in FEV1.0 in a patient with emphysema?

Answer 65

Decreased.

Question 66

What is the expected change in FVC in a patient with emphysema?

Answer 66

Decreased.

Question 67

What is the expected change in FEV1.0/FVC ratio in a patient with emphysema?

Answer 67

Decreased.