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Human Physiology > Respiratory System: Ventilation and Gas Exchange > Flashcards

Respiratory System: Ventilation and Gas Exchange Flashcards

1
Q

The volume of air in the lungs is determined by what two factors?

A
  1. the magnitude of the pressure change during inspiration or expiration
  2. the stretchability of the lung
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2
Q

What describes the stretchability of the lung? How is it defined?

A

Lung compliance describes the stretchability of the lung (specifically, their elastic connective tissues)

it is defined as the change in lung volume for a given change in pressure or

CL = ∆VL/(Palv-Pip) = ∆VL / Ptp

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3
Q

Compliance is the inverse of ___ and is indicative of the amount of muscle ___ needed to ___ the lung.

A

stiffness; force; ventilate

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4
Q

What two factors contribute to compliance?

A
  1. lung elasticity

2. surface tension

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5
Q

If the lung elasticity is high, V ___ rapidly per unit change in P. However, if the lung elasticity is low, V ___ slowly per unit change in P.

A

increases; increases

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6
Q

What happens to compliance if lung tissues thicken?

A

there would be a decrease in compliance

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7
Q

What is the measure of the intermolecular attractive forces that stabilize liquid?

A

Surface tension

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8
Q

T/F. Surface tension pulls molecules together at an air-liquid interface.

A

True.

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9
Q

For polar molecules like water, what creates the surface tension?

A

electrostatic force

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10
Q

Forces are strong on the ___ side, but weak on the ___ side.

A

liquid; air

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11
Q

T/F. A net force pulls the surface molecules toward the air phase which reduces the surface tension.

A

False, A net force pulls the surface molecules toward the WATER phase which reduces the surface tension.

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12
Q

The remaining surface molecules exert an opposing force called ___ ___.

A

surface tension

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13
Q

Because there is a ___ charge at the surface to repel molecules, water forms ___.

A

negative; droplets

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14
Q

Surface tension in a ___ cause the liquid lining to be pulled toward the ___. These forces generate an inner pressure that is ___ to surface tension and ___ proportional to the radius of the bubble.

A

bubble; center; proportional; inversely

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15
Q

P = 2x ___ ___ / ___

A

P = 2x surface tension / radius

increase in ST = increase in P
decrease R = increase P

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16
Q

T/F. If bubbles of different sizes are connected, the pressure difference will be different in each bubble.

A

False, If bubbles of different sizes are connected, the pressure difference will EQUILIBRATE as air flows from bubble 2 into bubble 1

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17
Q

T/F. Surface tension tends to pull the alveolar walls outward.

A

False, surface tension tends to pull the alveolar walls INWARD.

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18
Q

Like connected bubbles, alveoli are connected to each other so the smallest ones are at the ___ risk of collapsing.

A

greatest

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19
Q

Ventilation must produce enough force to counteract what? How is this force minimized?

A

tension

by using surfactant

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20
Q

What cells produce surfactant? What does surfactant do?

A

Type II cells

reduces the surface tension by reducing intermolecular forces between water molecules.

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21
Q

Why is surfactant important in small alveoli?

A

So that alveoli can be small and numerous (which increases surface area for gas exchange)

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22
Q

Surfactant is a ___ phospholipid + protein that forms a ___ between air and water. The ___ tails pulls the surfactant molecule upwards.

A

amphipathic; monolayer; hydrophobic

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23
Q

What concentrates surfactant at the surface? How does this reduce surface tension?

A

hydrophilic / hydrophobic interactions

by decreasing density of H2O molecules

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24
Q

T/F. Surfactant creates additional surface tension and will decrease compliance.

A

False, Surfactant does NOT create additional surface tension and will INCREASE compliance.

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25
Q

T/F. Surfactant has a greater effect in larger alveoli as compared to small.

A

False, Surfactant has a greater effect in SMALL alveoli

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26
Q

T/F. The reduction in surface tension helps to maintain a pressure in smaller alveoli equal to that in larger ones.

A

True.

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27
Q

How is the production of surfactant regulated?

A
  1. by stretch receptors in Type II cells

2. deep breathing increases surfactant production

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28
Q

Which is more important in determining lung compliance, surface tension or lung elasticity?

A

surface tension

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29
Q

Surfactant deficiency leads to ___ ___. Acute ___ ___ syndrome is the ___nd leading cause of death in premature infants. Why?

A

respiratory distress; respiratory distress; 2

  1. insufficient surfactant production
  2. lungs resists expansion so not enough O2 enters
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30
Q

What type of therapy is given to these premature infants?

A

artificial surfactant and mechanical ventilation (high O2 environment)

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31
Q

Airflow is ___ ___ to airway resistance (flow = ∆P/R) and the tube ___ is the primary determinant of resistnace with resistance being proportional to ___.

A

inversely proportional; radius; 1/r^4

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32
Q

What factors other than airflow affect R? How?

A

transpulmonary pressure - dilates bronchioles during inspiration
elasticity of tissues between outside of airways and alveolar walls also open airways during inspiration
neural and chemical control of smooth muscles

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33
Q

T/F. Epi dilates smooth muscles to increase flow and cytokines released during inflammation cause muscular constriction causing an increase in R and a decrease in F.

A

True.

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34
Q

If there is an increase in resistance due to mucus or an inflammatory response, one will breath more ___ to increase ∆P and breath more ___ because airflow during expiration is limited.

A

deeply; slowly

35
Q

If there is a decrease in compliance due to the lungs not stretching as much, one will breath more ___ to compensate for reduced ∆V and ∆P and they will breath more ___ to minimize muscle effort (use less muscle energy).

A

rapidly; shallowly

36
Q

Why does asthma cause increase airway resistance?

A

because of inappropriate contraction of smooth muscle

37
Q

In asthma, an increase in R causes a ___ in airflow. This can be treated with ___ therapy and/or ___.

A

decrease; glucocorticoid (inhibit inflammation); bronchodilators (epi will stimulate relaxation of smooth muscle to dilate airways)

38
Q

___ and ___ are examples of chronic obstructive pulmonary diseases that increase airway ___ and are often associated with ___.

A

Emphysema; chronic bronchitis; smoking

39
Q

What causes emphysema?

A

alveolar tissues damaged or destroyed, perhaps due to overproduction of proteolytic enzymes

40
Q

T/F. In emphysema, enzymes degrade elastic fibers in the lungs creating many large alveoli with low compliance that don’t expand easily.

A

True.

41
Q

What does emphysema result in?

A

airway collapse
lack of recoil
difficulty in expiring

42
Q

In chronic bronchitis there is ___ or ___ that impair airflow thereby ___ resistance and ___ breathing

A

mucus; inflammation; increased; deeper

43
Q

The Heimlich maneuver dislodges particulate matter from the ___ respiratory tract by ___ the pressure in the thorax.

A

upper; increasing

44
Q

Match the following:

  1. tidal volume
  2. inspiratory reserve volume
  3. expiratory reserve volume
  4. residual volume
  5. vital capacity
  6. total lung capacity
A. V exhaled beyond TV
B. vital capacity + residual volume
C. max V inspired
D. V entering lungs per breath
E. IRV + ERV + TV
F. V in lungs after maximum exhalation
A 
1  - D
2 - C
3 - A
4 - F
5 - E
6 - B
45
Q

Match the following:

  1. tidal volume
  2. inspiratory reserve volume
  3. expiratory reserve volume
  4. residual volume
  5. vital capacity
  6. total lung capacity
A. 500ml
B. 1000ml
C. 1500ml
D. 3000ml
E. 5000ml
F. 6000ml
A 
1 - A
2 - D
3 - C
4 - B
5 - E
6 - F
46
Q

What are the two clinically relevant measures?

A
  1. vital capacity - how well lungs expand relative to max pressure change
  2. forced expiratory volume in 1 second (FEV1) - indicates resistnance and how much VC can be exhaled in 1 sec
47
Q

What are the FEV1 and VC in obstructive and restrictive lung disease?

A

Obstructive (take more muscle energy): ↓FEV1 and normal VC

Restrictive (nothing blocking air leaving lung): ↓VC and normal FEV1

48
Q

What is the minute ventilation (ml.min) at rest?

A

Minute ventilation = tidal V x respiratory rate

= 500ml x 10 breaths/min
=5000ml/min

49
Q

T/F. All air enters the alveoli.

A

False, all air does NOT reach the alveoli so must consider dead space

50
Q

The ___ dead space (~___ml) reduces the amount of fresh air reaching the alveoli. It is the volume in the ___ airways left over from preceding breath.

A

anatomical; 150; conducting

51
Q

T/F. The anatomical dead space increases the alveolar ventilation (AV) which is a more accurate measure of air reaching the alveoli.

A

False, The anatomical dead space DECREASES the alveolar ventilation (AV) which is a more accurate measure of air reaching the alveoli.

52
Q

AV = (___V - ___ space) x ___ rate

A

AV = (tidal V - dead space) x respiratory rate

53
Q

What does it mean if the AV is equal to zero?

A

that the patient is not breathing deeply enough to overcome the dead space

54
Q

Alveolar ventilation differs dramatically and one sees a bigger change when taking a ___ breath (↑TV) than increasing the ___ rate.

A

deeper; respiratory

55
Q

What happens during exercise to the ventilation?

A

↑ rate + breathing deeply to ↑ TV + frequency therefore don’t double ventilation by only ↑ rate

56
Q

When does an alveolar dead space exist?

A

when there is a mismatch between ventilation and bloodflow

57
Q

T/F. The alveolar dead space is always zero, even in normal lungs, due to the effects of gravity on bloodflow.

A

True.

The perfusion at the apex of the lung is not a good as at the base

58
Q

___ dead space is the sum of anatomical dead space + alveolar dead space.

A

Physiologic

59
Q

Define external and internal respiration.

A

External: gas exchange between air and blood in lung
Internal: gas exchange between blood and cells (interstitial fluid)

60
Q

What are the steps of respiration?

A
  1. Ventilation (bulk flow) - moving gas from exchange of air
  2. external respiration (diffusion) - O2 diffuses into blood + CO2 diffuses into air
  3. gas transport in blood (bulk flow) - O2 in blood to tissues of body via blood flow
  4. internal respiration (diffusion) - O2 diffuses into ISF from blood at target cells
  5. cellular respiration (consume O2 and produce CO2) - get into mitochondria for oxidative phosphorylation → ATP
61
Q

What does Dalton’s law for gases in a mixture of gases state?

A

that the total pressure is the sum of the individual pressures

62
Q

Individual pressures are called ___ pressures.

A

partial

63
Q

T/F. The pressure exerted by gas is independent of pressure exerted by other gases and is proportional to temperature and concentration.

A

True.

64
Q

How do gases diffuse?

A

from high to low partial pressures

65
Q

In the atmosphere, what does Patm equal?

A

sum of all the partial pressures

66
Q

T/F. Partial pressures will not vary with altitude, but the composition does.

A

False, Partial pressures WILL vary with altitude, but the composition does NOT.

67
Q

What is the PO2 at sea level? In Denver?

A

sea level: 760mmHg = total pressure (21% O2 but diff PO2 = 160mmHg

in Denver: 640mmHg = total pressure (21% O2 but diff PO2 = 130mmHg

68
Q

___ law states that the amount of gas dissolved in a liquid is proportional to the partial pressure of that gas in equilibrium with the liquid.

A

Henry’s

69
Q

T/F. At equilibrium, Pgas in gas phase equals the Pgas in the liquid phase. At a gas mixture/liquid interface, gas will diffuse along a partial pressure gradient.

A

True.

70
Q

What two things does the parital pressure vs concentration of a gas in liquid depend on?

A
  1. which gas it is and partial pressure of the gas

2. temperature (↑temp = ↓ solubility of a gas)

71
Q

Match the different tissues with the partial pressures.

  1. alveolar air
  2. alveolar venous capillaries
  3. systemic arteries
  4. tissue capillaries
  5. systemic veins
  6. arterial alveolar capillaries
  7. air

A. PO2 = 105mmHg, PCO2 = 40mmHg
B. PO2 = 40mmHg, PCO2 = 46mmHg
C. PO2 = 100mmHg, PCO2 = 40mmHg
D. PO2 = 160mmHg, PCO2 = 0.3mmHg

A 
1 - A
2 - C
3 - C
4 - B
5 - B
6 - B
7 - D
72
Q

Why is the PO2 less than 5mmHg in the mitochondria?

A

O2 is being consumed quickly to maintain gradient for more O2 to diffuse in

73
Q

Alveolar PO2 (how much O2 is available to the blood) is determined by what three factors?

A
  1. atmospheric PO2
  2. rate of alveolar ventilation
  3. rate of cellular O2 consumption
74
Q

Match the following conditions with the change in alveolar PO2 and alveolar PCO2.

  1. breathing air with low PO2
  2. ↑ alveolar ventilation and unchanged metabolism (not consuming or producing more O2)
  3. ↓alveolar ventilation and unchanged metabolism
  4. ↑ metabolism and unchanged alveolar ventilation
  5. ↓ metabolism and unchanged alveolar ventilation
  6. proportional increases in metabolism and alveolar ventilation (balanced; majority of homeostatic mechanism)

A. Increase; Decrease
B. Decrease; Increase
C. Decrease; No Change
D. No Change; No Change

A 
1 - C
2 - A
3 - B
4 - B
5 - A
6 - D
75
Q

In ___ the ventilation is decreased relative to the metabolism so a patient breathes more slowly. The alveolar PO2 is ___ and alveolar PCO2 is ___.

A

Hypoventilation; decreased; increased

76
Q

In ___ the ventilation is decreased relative to the metabolism so a patient breathes more frequently. The alveolar PO2 is ___ and alveolar PCO2 is ___.

A

Hyperventilation; increased; decreased

77
Q

Why does hyperventilation not occur during exercise?

A

the metabolic rate also increases during exercise to counteract the ↑PO2 and ↓PCO2

78
Q

What happens the to PO2 at high altitudes?

A

there is lower PO2 in the air so lower alveolar PO2 therefore the rate at which O2 diffuses into blood is severely reduced

79
Q

T/F. O2 uptake continues along the length of the alveolar capillaries.

A

True

80
Q

T/F. The alveolar has a small safety factor.

A

False, it is not used in the normal lung and large for diseased lungs to allow for diffusion of sufficient O2

81
Q

Pulmonary edema fills some alveoli with ___. Diffuse ___ ___ thickens the alveolar walls.

A

fluid; interstitial fibrosis

82
Q

Why are gas exchange problems greater for O2 than CO2?

A

O2 is not a soluble in H20 as CO2 so CO2 is able to move faster from one fluid to another than O2

83
Q

Ventilation-perfusion inequalities will ___ blood PO2. List two conditions.

A

lower

  1. vascularized space with no ventilation
  2. ventilated space with no blood supply
84
Q

How do local responses in smooth muscle minimize ventilation, such as perfusion mismatches due to bronchoconstriction and vasoconstriction?

A

bronchoconstriction: ↓air flow → ↓alveolar PO2 → ↓blood PO2 → vasoconstriction → ↓blood flow
vasoconstriction: ↓blood flow → ↓alveolar PCO2 → bronchoconstriction → decreased air flow

Human Physiology (22 decks)

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