Jackson 2

Question 1

The volume of air in the lungs is determined by the

Answer 1

magnitude of the pressure change during inspiration or expiration, and the stretchability of the lung.

Question 2

Lung compliance describes this

Answer 2

stretchability, and is defined as the change in lung volume for a given change in pressure or

Question 3

Compliance is the inverse of ——, and is indicative of the needed to ventilate the lung.

Answer 3

stiffness, amount of muscle

Question 4

Two factors contribute to compliance

Answer 4

lung elasticity

surface tension

Question 5

Lung elasticity: • if high (green line in figure) –

Answer 5

V increases rapidly per unit change in P

Question 6

Lung elasticity:

• if low (red line in figure) –

Answer 6

V increases slowly per unit change in P

Question 7

2. surface tension

Answer 7

• measure of the intermolecular attractive forces that stabilize liquid
• these forces pull molecules together at an air-liquid interface

Question 8

• for polar molecules like water, surface tension is created by

Answer 8

electrostatic force

Question 9

Forces are strong on the —- side, but weak on the —- side.

Answer 9

liquid, air

Question 10

Consequently, a net force pulls surface molecules toward the

Answer 10

water phase which reduces surface area. The remaining surface molecules exert an opposing force called surface tension.

Question 11

Surface tension (ST) in bubbles cause the liquid lining to be pulled toward the

Answer 11

center (note that in a bubble there are two air/liquid interfaces).

Question 12

inner pressure that is proportional to

Answer 12

surface tension and inversely proportional to the radius of the bubble
P = 2 x surface tension / radius

Question 13

increase ST →

Answer 13

increase pressure

Question 14

decrease radius →

Answer 14

increase pressure

Question 15

If bubbles of difference size (e.g. r1 = 2r2; r1 > r2) are connected, the pressure difference will

Answer 15

equilibrate as air flows from bubble 2 into bubble 1.

Question 16

Surface tension exists at the air-water interface in

Answer 16

alveoli, and, as in bubbles, tends to pull the alveolar walls inward. alveoli are connected to each other so the smallest ones are at the greatest risk of collapsing.

Question 17

Ventilation must produce enough force to counteract the

Answer 17

tension.

Question 18

The amount of force required is minimized by using surfactant from

Answer 18

Type II cells to reduce surface tension.

Question 19

Surfactant reduces surface tension by reducing

Answer 19

intermolecular forces between water molecules. Thus, alveoli can be small and numerous, which increases surface area for gas exchange.

Question 20

Surfactant is an

Answer 20

amphipathic phospholipid + protein molecule that forms a monolayer between air and water.

Question 21

Hydrophilic/hydrophobic interactions concentrate

Answer 21

surfactant at the surface.

Question 22

Reduces surface tension by

decreasing density of

Answer 22

H2O molecules

Question 23

Surfactant does not create

Answer 23

additional surface tension and will increase compliance.

Question 24

surfactant has greater effect in

Answer 24

small alveoli than in large

Question 25

production is regulated by stretch receptors in

Answer 25

Type II cells; deep breathing increases surfactant production

Question 26

Overcoming surface tension is more important than ------- in determining lung compliance

Answer 26

lung elasticity

Question 27

Surfactant deficiency leads to respiratory distress. Acute respiratory distress syndrome is the 2nd leading cause of death in

Answer 27

premature infants

Question 28

Airflow is inversely proportional to

Answer 28

airway resistance (re: flow = ΔP/R), and the tube radius is the primary determinant of R with R (resistance) being proportional to 1/r4

Question 29

Other factors affecting R include: transpulmonary pressure –

Answer 29

dilates bronchioles during inspiration

Question 30

Other factors affecting R include: elasticity of tissue between outside of airways and alveolar walls also

Answer 30

opens airways during inspiration

Question 31

Other factors affecting R include: neural and chemical

Answer 31

control of smooth muscles

Question 32

Abnormalities in compliance and resistance have contrasting effects on

Answer 32

breathing

Question 33

increase R leads to

Answer 33

breathe more deeply (to increase ΔP) breathe more slowly because airflow during expiration is limited

Question 34

decrease compliance

Answer 34

breathe more rapidly to compensate for reduced ΔV and ΔP | breathe shallowly to minimize muscle effort

Question 35

Asthma causes increased airway resistance because of inappropriate contraction of

Answer 35

smooth muscle

Question 36

increase R ----> Can be treated with....

Answer 36

à decrease airflow can be treated with glucocorticoid therapy and/or bronchodilators

Question 37

Chronic obstructive pulmonary disease (COPD) also increases

Answer 37

airway resistance; often associated with smoking

Question 38

Emphysema - alveolar tissues

Answer 38

damaged or destroyed, perhaps due to overproduction of proteolytic enzymes results in airway collapse, lack of recoil, and difficulty in expiring

Question 39

Chronic bronchitis - mucus or inflammation impairs

Answer 39

airflow increased resistance --> deeper breathing

Question 40

tidal volume (TV) –

Answer 40

V entering lungs per breath; ~500 ml

Question 41

inspiratory reserve volume (IRV) –

Answer 41

max V inspired ; ~3000 ml

Question 42

expiratory reserve volume (ERV) –

Answer 42

V exhaled beyond TV; ~1500 ml

Question 43

residual volume –

Answer 43

V in lungs after maximum exhalation; ~1000 ml

Question 44

vital capacity – IRV + ERV + TV; ~

Answer 44

5000 ml

Question 45

total lung capacity – vital capacity + residual volume; ~

Answer 45

6000 ml

Question 46

Clinically relevant measures

Answer 46

vital capacity forced expiratory volume in 1 second (FEV1)

Question 47

obstructive lung disease:

Answer 47

↓ FEV1; normal VC

Question 48

restrictive lung disease:

Answer 48

↓VC, normal FEV1

Question 49

Minute ventilation (ml per min) =

Answer 49

tidal V x respiratory rate, e.g. at rest, minute ventilation = 500 ml x 10 breaths/min = 5000 ml/min

Question 50

But not all air reaches

Answer 50

alveoli so must consider dead space.

Question 51

Anatomical dead space (~150 ml) reduces the amount of

Answer 51

fresh air reaching alveoli.

Question 52

Anatomical dead space reduces

Answer 52

alveolar ventilation (AV) which is a more accurate measure of air reaching the alveoli.

Question 53

AV =

Answer 53

(tidal V – dead space) x respiratory rate

Question 54

Alveolar dead space exists when there is a mismatch between

Answer 54

ventilation and bloodflow

Question 55

Alveolar dead space is always greater than -----, even in normal lungs, due to the effects of

Answer 55

zero, gravity on bloodflow

Question 56

Physiologic dead space is the sum of

Answer 56

anatomical dead space + alveolar dead space

Question 57

External respiration - gas exchange between

Answer 57

air and blood in pulmonary capillaries

Question 58

Internal respiration – gas exchange between

Answer 58

blood in systemic capillaries and cells (interstitial fluid)

Question 59

Steps of respiration

Answer 59

1. ventilation (bulk flow) – 2. external respiration (diffusion) – 3. gas transport in blood (bulk flow) – 4. internal respiration (diffusion) – 5. cellular respiration - consume O2 and produce CO2

Question 60

Dalton’s Law for gases in a mixture of gases states that the total pressure is sum of the

Answer 60

individual pressures

Question 61

pressure exerted by gas is independent of

Answer 61

pressure exerted by other gases; proportional to temperature & concentration

Question 62

Partial pressures will vary with altitude, but ------ does not

Answer 62

% composition

Question 63

Henry’s Law states that the amount of gas dissolved in a liquid is proportional to the

Answer 63

partial pressure of that gas in equilibrium with the liquid

Question 64

at equilibrium, Pgas is gas phase equals

Answer 64

Pgas in liquid phase

Question 65

At a gas mixture/liquid interface, gas will diffuse along a

Answer 65

partial pressure gradient

Question 66

Alveolar PO2 (how much O2 is available to the blood) is determined by

Answer 66

atmospheric PO2 – rate of alveolar ventilation – rate of cellular O2 consumption

Question 67

To summarize, alveolar gas pressures are altered by ratio of

Answer 67

ventilation to metabolism

Question 68

Local responses in smooth muscle minimize

Answer 68

ventilation –perfusion mismatches due to bronchoconstriction (left side below) or vasoconstriction (right side)

Question 69

Ventilation rates will affect

Answer 69

alveolar gas pressure

Question 70

Hypoventilation – ventilation decreased relative to

Answer 70

metabolism

Question 71

Ventilation-perfusion inequalities | These will lower

Answer 71

blood PO2. Recall there is always a normal mismatch due to gravity making perfusion greater at base of lung.