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Physiology I > Exam 3: Pulmonary Ventilation, Gas Exchange And Gas Transport > Flashcards

Exam 3: Pulmonary Ventilation, Gas Exchange And Gas Transport Flashcards

1
Q

What percentage of blood is oxygen is transported bound to hemoglobin?

A

97%

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2
Q

The remaining 3% of blood oxygen that is not bound to hemoglobin is transported how?

A

As a dissolved gas

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3
Q

The oxyhemoglobin dissociation curve is a graph that shows what?

A

The relationship between the partial pressure of oxygen and hemoglobin binding/saturation

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4
Q

The oxyhemoglobin dissociation curve shows at the arterial partial pressure of oxygen (~95 mmHg) will results in what percentage of hemoglobin binding/saturation?

A

95-100% (~97% on average)

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5
Q

The oxyhemoglobin dissociation curve shows at the venous partial pressure of oxygen (~45 mmHg) will results in what percentage of hemoglobin binding/saturation?

A

~ 70%

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6
Q

What is the effect of a lower venous saturation of hemoglobin vs. arterial saturation?

A

It causes the oxygen to be unloaded at the tissue

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7
Q

An increase in activity/exercise will affect the venous saturation of hemoglobin how?

A

Decrease % saturation

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8
Q

What is the atmospheric partial pressure of oxygen?

A

105 mmHg

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9
Q

At atmospheric partial pressure of oxygen (i.e. in the alveoli of the lungs), what is the saturation of hemoglobin and what would happen if the partial pressure of oxygen was increased beyond atmospheric (105 mmHg)?

A

Hemoglobin is almost fully saturated at atmospheric pressure and increasing the partial pressure beyond this has little effect of saturation due to the nature of the dissociation curve of hemoglobin

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10
Q

What partial pressure results in pure oxygen saturation?

A

760 mmHg

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11
Q

Why is pure oxygen dangerous to breath?

A

Because molecular oxygen ins highly oxidative and can uncouple respiratory chain in the mitochondria of type 1 pneumocytes, resulting in cell death and permanent damage after 24 hours of exposure

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12
Q

What conditions in the tissue would result in the oxyhemoglobin dissociation curve shifting to the right?

A
  • Increased H+ (decreased pH)
  • increased temperature
  • increased 2,3-DPG
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13
Q

What is it called when the dissociation curve of oxyhemoglobin shifts to the right?

A

Bohr effect

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14
Q

What the hemoglobin dissociation curve shifts to the right due to increased metabolism of tissues, what effect does this ultimately have on oxygen delivery? Why?

A

Increased oxygen delivery because the hemoglobin saturation (i.e. oxygen binding capacity of hemoglobin) is lowered, thus increasing unloading behavior at the tissue

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15
Q

There are three ways that carbon dioxide is transported in the blood. What is the most common method and what percentage of blood carbon dioxide is transported that way?

A

~ 70% transported as bicarbonate ion (HCO3-)

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16
Q

There are three ways that carbon dioxide is transported in the blood. What are the two less common methods?

A

~ 7% transported as a dissolved gas

~ 23% bound to hemoglobin

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17
Q

The formation of carbonic acid from water and carbon dioxide is catalyzed by what?

A

Carbonic anhydrase

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18
Q

At the tissue level, what happens to chloride anions?

A

They move inside the RBC to balance charge

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19
Q

At the lungs, what happens to chloride anions?

A

They move outside the RBC to balance charge

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20
Q

As an RBC passes though a tissue capillary bed where metabolism is happening, what happens?

A
  • ↑ CO2
  • ↓ pH or ↑ H+ (from about 7.45 to 7.35)
  • ↑ HCO3-
  • ↓ plasma Cl-
  • ↑ O2 delivery (the Bohr Effect)
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21
Q

As an RBC passes through a pulmonary capillary bed where ventilation is happening, what happens?

A
  • ↓ CO2
  • ↑ pH or ↓ H+ (from about 7.35 to 7.45)
  • ↓ HCO3-
  • ↑ plasma Cl-
  • ↑ O2 uptake (the Bohr Effect in a “kind” of reverse)
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22
Q

What is the Haldane effect?

A

↑ O2 displaces H+ from hemoglobin, which drives the carbonic acid reaction in a direction such that there is
↑ CO2 release from the blood

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23
Q

Respiration, the process of breathing

A

Pulmonary ventilation

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24
Q

Normal, quiet, resting breathing depends on

A

Abdominal breathing

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25
Q

Contracting the diaphragm pulls it in which direction and what part of the cycle of breathing results?

A

Downward; inhalation

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26
Q

Relaxing the diaphragm draws it in which direction and what part of the cycle of breathing results?

A

Upward; relaxation/exhalation

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27
Q

Rib-cage muscles of inhalation

A
  • External intercostals
  • Some parasternal intercostals
  • Anterior scalene
  • Serratus anterior
  • Sternocleiodomastoid
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28
Q

Rib-cage muscles of exhalation

A
  • Rectus abdominus

- Internal intercostals

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29
Q

Restful breathing is predominantly

A

Diaphragmatic

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30
Q

Vigorous breathing is predominately

A

Rib-cage based

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31
Q

All the muscles of ventilation serve to change the shape of the chest and therefore change the

A

Pressure on the lungs

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32
Q

What kind of pressure is the pleural cavity under?

A

Negative pressure

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33
Q

Name the space between the lungs and the thoracic wall

A

Intrathoracic or intrapleural space

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34
Q

Name the space within the lungs

A

Intrapulmonic (lung) space

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35
Q

What is the substance that type 2 pneumocytes release in the intrapleural space that lessen H2O effects

A

Surfactin

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36
Q

How do you change the intrapleural pressure?

A

Increase or decrease the size of thorax

Note: the lungs will follow the change in shape because they want to keep the negative pressure

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37
Q

Pressure against the lung walls that is a combination of inside and outside pressure

A

Transmural pressure

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38
Q

Three types of work that must be done in order to breath

A
  1. Respiratory work/compliance work
  2. Airway work
  3. Tissue work/tissue resistance work
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39
Q

What type of work is required where all energy (in an ideal system) is converted into air movement

A

Respiratory/compliance work

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40
Q

Respiratory work =

A

Force X distance

Force is pressure
Distance is volume

So respiratory work is pressure X volume

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41
Q

What type of work is it where some energy is used to move tissues around

A

Tissue resistance work

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42
Q

T/F. More tissue work is required in ribcage-based ventilation.

A

True.

More tissue work required within breathing shifts from diaphragmatic to ribcage-based. Which is why ribcage is used second over the diaphragm.

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43
Q

What kind of work is required to overcome the drag on all respiratory tree linings?

A

Airway work

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44
Q

Obstructed airways or bronchi-constricted ones (ie. Asthma) would require what kind of work

A

Airway work

Q =∆P/R

Q is airflow
∆P is atmospheric vs. intrapulmonic pressure
R is airway drag

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45
Q

The prime determinant in airway work is

A

R^4, or the airway drag

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46
Q

Exhalation is a matter of capturing stored energy of inspiration. Then deduct tissue and airway work of expiration and the remaining is the

A

Free work of expiration

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47
Q

Total energy spent breathing

A

3-5%

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48
Q

Airway restrictions and tissue scarring may

A

Increase the work of breathing

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49
Q

Regular amount of air ventilated per breath

A

Tidal volume (500 ml)

50
Q

Amount of air that can be inhaled after tidal volume

A

Inspiratory reserve volume (3,000 ml)

51
Q

Amount of air that can be exhaled after tidal volume

A

Expiratory reserve volume (1,000 ml)

52
Q

Expiratory reserve + tidal volume + inspiratory reserve

A

Vital capacity (4,500 ml)

53
Q

Amount of air still in lungs after complete exhalation

A

Residual volume (1,000 ml)

54
Q

Vital capacity + residual volume

A

Total lung capacity (5,500 ml)

55
Q

Tidal volume

A

500 ml

56
Q

Inspiratory reserve volume

A

3,000 ml

57
Q

Expiratory reserve volume

A

1,000 ml

58
Q

Vital capacity

A

4,500 ml

59
Q

Residual volume

A

1,000 ml

60
Q

Total lung capacity

A

5,500 ml

61
Q

Vital capacity is dependent on

A

Normal and abnormal anatomical and physiological factors

62
Q

Normal anatomical factors that impact vital capacity

A 
Body size (large = ↑VC)
Body type (tall/thin = ↑VC )
63
Q

Abnormal anatomical factors that impact vital capacity

A

Kyphosis or scoliosis scoliosis (↓VC)

Respiratory paralysis like polio, cervical injury (↓VC)

64
Q

Normal physiological factors that impact vital capacity

A 
Muscle strength (conditioned = ↑VC )
Vigor of effort (trying hard = ↑VC )
65
Q

Abnormal physiological factors that impact vital capacity

A 
Pulmonary congestion ↓VC
Reduced compliance (asthma, bronchitis, tuberculosis, pleurisy, etc) ↓VC
66
Q

A volume parameter that incorporates time as part of vital capacity measurement that is a forced inhale

A

Forced vital capacity (FVC)

67
Q

Amount of vital capacity exhaled in 1 second or 3 seconds that is often expressed as a % of VC

A

Forced expiratory volume

68
Q

Average flow during the middle part of forced vital capacity that lowers with obstructive diseases

A

Forced expiratory flow

69
Q

Spirometry is measuring

A

Volume and capacities (collection of volume) over time

70
Q

The total new air moved into the respiratory system per minute

A

Minute respiratory volume

71
Q

Minute respiratory volume equation

A

Tidal volume X respiratory rate

At rest: 500 ml X 12 bpm ~ 6 liters/minute

72
Q

What is the average minute respiratory volume

A

6 liters/minute

73
Q

The amount of air arriving at the alveoli

A

Minute alveolar volume

74
Q

T/F. Minute respiratory volume does NOT equal the amount of air arriving at alveoli

A

True

Some ventilated air is wasted filling up larger airways and do not participate in gas exchange. This is anatomical dead space.

75
Q

How much anatomical dead space in the body

A

150 ml in typical lungs

76
Q

Average minute alveolar volume

A

4.2 l/m

Tidal volume = 500 ml
Anatomical dead space = 150 ml
Breathing rate of 12 breath/min
= 4.2 l/m

77
Q

The atmospheric air that we breath has O2 pressure of about

A

160 mmHg

78
Q

The atmospheric air that we breath has CO2 pressure of about

A

0 mmHg

79
Q

How soluble is O2 and CO2 with water?

A

O2 not soluble

CO2 is very soluble

80
Q

CO2 is _____ more/less diffusable than O2

A

20X more

81
Q

Diffusion is a function of 3 factors

A
  1. Concentration gradients
  2. Solubility of gases
  3. Nature of barriers
82
Q

Gas solubility is determined by

A

Solubility coefficient (S) and molecular weight (MW) of the gas

83
Q

A concentration gradient concept represented as a _________ for a given gas

A

Pressure differential (∆P)

84
Q

Henry’s Law states that partial pressure X solubility =

A

Dissolved gas

85
Q

What is the prime determinant of gas exchange/diffusion (D) in the lungs (or tissues)

A

∆P or the pressure differential

Thus, D =∆P. Diffusion is determined by partial pressure of gas. And ∆P is determined by ventilation.

86
Q

What is O2 mmHg at atmospheric air at sea level?

A

160 mmHg

87
Q

What is CO2 mmHg at atmospheric air at sea level?

A

0 mmHg

88
Q

What is O2 mmHg in the lungs?

A

105 mmHg

89
Q

What is CO2 mmHg in the lungs?

A

40 mmHg

90
Q

What are the five things that affect partial pressure difference in the lungs?

A
  1. Mixing old and new air (takes 10 breaths to fully exchange all air)
  2. Humidification of incoming air (H2) displaces all partial pressures downward a little)
  3. Absorption/disappaearance of O2 into blood (as long is blood is flowing away from alveoli, O2 is swept away to the tissues)
  4. Production/liberation of CO2 from the blood (as long as flowing toward alveoli, CO2 is delivered to the lungs)
  5. Ventilation (rate and depth of breathing)
91
Q

How many breaths does it take to fully exchange all air

A

10+

Because of dead space and residual volume

92
Q

In humidification of air, what displaces all partial pressures downward a little?

A

H2O

93
Q

When blood flows away from alveoli, _____ is taken from the lungs to the tissues.

As long as blood flows to the alveoli, ____ is delivered from the tissues and to the lungs.

A

O2 goes to tissues; CO2 goes to lungs

94
Q

What is arguably the main factor that affects partial pressures in the lungs?

A

Ventilation

Note: This is the rate and depth of breathing combined that exchanges air on a cyclical basis.

95
Q

Resting consumption rate of O2 is ____; exercising consumption rate of O2 is ______

A 
Resting = 250 ml O2/min
Exercising = 1,000
96
Q

Resting consumption rate of CO2 is ____; exercising consumption rate of CO2 is ______

A 
Resting = 200 ml/min
Exercising = 800 ml/min
97
Q

Ventilation must [increase/decrease] during exercise in order to maintain normal alveolar PO2 (105 mmHg) and PCO2 (40 mmHg) levels

A

Increase

98
Q

Blood flow passing alveoli

A

Perfusion

99
Q

Ventilation-perfusion ration (V/Q)

A

Want air in lungs to go to the same places as blood is bringing CO2

Note: Also called V-P matching. Too much ventilation is a waste of work. Too little ventilation will not allow for full gas exchange.

100
Q

When V/Q = 0, there is

For example: blocked alveolus

A

No ventilation

Note: physiological shunt occurs

101
Q

When V/Q = 0 and there is no ventilation, what do PO2 and PCO2 levels change from and to?

A 
PO2 = 105 ↓ 40 mmHg 
PCO2 = 40 ↑ 45 mmHg
102
Q

When V/Q = infinity, there is

For example: obstructed blood vessel

A

No blood flow

Note: physiological dead space is formed (similar to anatomical dead space, though not for anatomy reasons)

103
Q

When V/Q = infinity and there is no blood flow, what do PO2 and PCO2 levels change from and to?

A 
PO2 = 105 ↑ 160 mmHg
PCO2 = 40 ↓ 0 mmHg
104
Q

Normal V/Q is about

A

0.8 (no associated units)

Note: actual V/Q varies through the [at rest] lungs

105
Q

V/Q is “high” or “low” or “just right” in thirds of the lungs at rest. What 1/3 of the lung is associated with each zone?

A
  • High V/Q in upper 1/3 of lungs
  • Just V/Q right in middle 1/3rd
  • Low V/Q in lower 1/3 lungs

Note: this is V/Q with a lung at rest. During exercise, redistribution occurs and all areas develop V/Q relationships as BP and flow increase

106
Q

What happens to V/Q in the upper 1/3 of the lungs with exercise?

A

Better Q

107
Q

In hypoxic conditions, what happens to blood vessels and why? (Recall from exam 2)

A

↓ O2 = vasoconstriction so that V/Q can be preserved by redirecting blood flow to better ventilated areas

108
Q

In 1 second travel through capillary results in a movement of O2 from ____ to ___. Average is ____

A

Initially 65 mmHg ↓ 0 mmHg; average 11 mmHg at rest

109
Q

Systemic arterial blood PO2

A

95 mmHg

110
Q

Upon arriving at tissues, O2 level

A

Drops to 40 mmHg

111
Q

O2 in a cell’s cytoplasm

A

25 mmHg

112
Q

O2 in mitochondria of a cell

A

5 mmHg

113
Q

A measure of difference in PO2 from systemic arterial blood to the systemic venous blood

A

Arterio-Venous Oxygen Difference

Note: this concept expresses amount of O2 removed by tissues

114
Q

Arterio-Venous Oxygen Difference at rest

A

55 mmHg

115
Q

Increase in AV O2 difference (Arterio-Venous Oxygen Difference) means that

A

Tissues are metabolizing more

116
Q

Systemic venous blood PO2

A

40 mmHg

117
Q

Upon arrival at tissues, CO2 level rises to

A

45 mmHg

118
Q

Systemic venous blood PCO2

A

45 mmHg

119
Q

In 1 second travel through capillary results in a movement of CO2 from ____ to ___.

A

5 mmHg; 0 mmHg

120
Q

Local flow is primarily controlled by the release of local factors at tissues which causes

A

Vasodilation

121
Q

Vasodilation will allow for more efficient

A

CO2 removal and O2 delivery

Physiology I (15 decks)

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