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HSC1007 > Respiratory system Week 5 > Flashcards

Respiratory system Week 5 Flashcards

1
Q

How are airflow rates measured by

A

Spirometry

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2
Q

Effective oxygenation and CO2 removal in lungs dependent on

A

1) Ventilation and gas exchange by diffusion

2) Perfusion of lungs

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3
Q

What are the factors influencing efficiency of diffusion across alveolar capillary border

A

1) Partial pressure of gases

2) surface area

3) thickness of barrier

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4
Q

What are partial pressures of gasses

A

Pressure exerted by gas in mixture of gasses

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5
Q

What law does does partial pressure of gasses follow

A

Dalton’s law

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6
Q

How are partial pressures of gases calculated

A

% of gas in air x atmospheric pressure

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7
Q

Is the pressure exerted by gas in mixture of gases proportional

A

Yes

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8
Q

What are the factors of blood flow

A

Alveoli perfusion, rate of blood flow through alveoli

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9
Q

Why does alveolar gasses take time to diffuse and equilibrate with blood

A

Different gasses diffuse/equilibrate at different rates

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10
Q

When does gas exchange occur

A

When blood perfuses capillary

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11
Q

What are the factors influencing rate of gas transfer across alveolar membrane

A

1) Partial pressure gradients of O2 & CO2
2) Surface area of alveolar membrane
3) Thickness of barrier separating air and blood across alveolar membrane
4) Diffusion constant

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12
Q

What is the major determinant of rate of gas transfer

A

Partial Pressure gradients of O2 and CO2

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13
Q

What is the relationship between partial pressure gradient and rate of transfer

A

Greater partial pressure gradient = greater rate of transfer

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14
Q

What is the relationship between surface area and rate of transfer

A

Greater SA = greater rate of transfer

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15
Q

What happens to the surface area when one exercises

A

Surface area increases with increased opening of pulmonary capillaries with increased cardiac output and alveolar expansion

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16
Q

What is the relationship between barrier thickness and rate of transfer

A

Thicker = greater rate of transfer

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17
Q

What are pathological diseases that could cause increased thickness of barrier

A

Pulmonary edema, pulmonary fibrosis, pneumonia

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18
Q

What is the relationship between diffusion constant and rate of transfer

A

Greater diffusion constant = greater rate of transfer

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19
Q

How much greater is the diffusion constant of CO2 compared to O2

A

20x

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20
Q

Why is the diffusion constant of CO2 greater than O2

A

Helps to offset smaller partial pressure gradient of CO2 and allows for equal amount of CO2 and O2 transfer across membrane

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21
Q

What is the difference between pulmonary and systemic circulation

A

Pulmonary is normally dilated whereas systemic is normally constricted

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22
Q

What makes the pulmonary circulation unique in terms of its hemodynamic features

A

Low pressure, low resistance, high volume system

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23
Q

What is the distribution of blood flow in lungs

A

Non uniform

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24
Q

Do the lungs receive 100% of cardiac output at all times

A

Yes

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25
Q

What are the differences between systemic and pulmonary arterial pressure

A

Pulmonary artery >25/15 mmHg

Systemic artery 120/80 mmHg

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26
Q

What are the limited respiratory responses imposed by diseases

A

Increased dead space and decreased tidal volume

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27
Q

How is the tidal volume affected

A

Restriction of chest wall/lung movement. Loss of lung elasticity due to fibrosis (scarring) of alveolar walls

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28
Q

What is the differences between apex and base of lung in terms of its ventilation/perfusion ratio (V/Q)

A

Apex: High V/Q ratio due to greater pO2 and lower pCO2

Base: Low V/Q ratio due to lower pO2 and greater pCO2

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29
Q

How is the distribution of blood flow in perfusion of lungs influenced by

A

Gravity (Posture): Upright = more blood at bottom

Muscular tone of arterioles (vascular tone): less muscular walls in pulmonary arterioles compared to systemic arterioles
- can distend easier with more blood flow
- vasoconstriction = less blood flow through capillaries

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30
Q

How does the body attempt to do homeostasis of hypocapnia

A

Receptors detect decreasing PCO2 and increasing pH

Respiratory muscles inhibited

Decrease rate of respiration and decrease PCO2 elimination

Arterial PCO2 increases

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31
Q

How does the body attempt to do homeostasis of hypercapnia

A

Receptors detect increasing PCO2 and decreasing pH

Respiratory muscles stimulated

Increase rate of respiration and increase PCO2 elimination

Arterial PCO2 decreases

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32
Q

What is residual volume

A

Volume of air left in lungs after maximum expiration

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33
Q

What is tidal volume

A

Volume of air entering lungs at each resting breath/exiting lungs on passive expiration

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34
Q

What is expiratory reserve volume

A

Extra air expelled from lungs with max expiration after passive expiration

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35
Q

What is inspiratory reserve volume

A

Extra air entering lungs with max inspiration in addition to TV

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36
Q

What factors influence the ventilation volumes

A

Physical fitness, age, size

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37
Q

What other ventilation volumes does exercise recruit

A

IRV and ERV

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38
Q

What factors influence the ability to ventilate

A

Chest wall, lungs, others (pain, abdominal movement restricted)

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39
Q

How is vital capacity calculated

A

ERV + IRV + TV

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40
Q

What are the chemical controls of breathing

A

PCO2, PO2, H+

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41
Q

How is H+ and PO2 monitored

A

Carotid and aortic bodies

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42
Q

When does PO2 activate peripheral chemoreceptors

A

when arterial PO2 < 60 mmHg

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43
Q

What scenario makes the arterial PO2 < 60 mmHg

A

Life threatening situation which invokes an emergency response

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44
Q

What does H+ not affect

A

Central chemoreceptors

45
Q

What is PCO2 as a chemical control of breathing

A

Main respiratory regulator

46
Q

What does PCO2 affect

A

Mainly affects central chemoreceptors

Weakly affects peripheral chemoreceptors

47
Q

What does H+ affect

A

Peripheral chemoreceptors

48
Q

Can CO2 pass through blood brain barrier

A

Yes

49
Q

Can H+ pass through blood brain barrier

A

No

50
Q

When does PCO2 affect central chemoreceptors

A

PCO2 > 70 - 80 mmHg which directly depresses respiratory center and central chemoreceptors

51
Q

What are the 2 main controls of respiration which increases ventilation

A

Medullary chemoreceptors (decreasing pH, increasing CO2)

Carotid and aortic body receptors (decreasing O2)

52
Q

How is minute ventilation calculated

A

TV x Respiratory rate = x L/min

53
Q

What causes deviations in minute ventilation

A

Hypoventilation = decreased ventilation

Hyperventilation = increased ventilation

Tachypnoea = increased rate of respiration

Dyspnea = distressful sensation of breathing

54
Q

How does the body compensate for large airflow, small blood flow

A

Decreasing CO2
- increased contraction of local airway smooth muscle
- increased constriction of local airways
- increased air resistance
- decreased airflow

Increasing O2
- relaxation of local pulmonary arteriolar smooth muscle
- blood vessel dilation
- decreased vascular resistance
- increased blood flow

55
Q

How does the body compensate for small airflow, large blood flow

A

Increasing CO2
- decreased contraction of local airway smooth muscle
- local airways dilation
- decreased air resistance
- increased airflow

Decreasing O2
- increased contraction of local pulmonary arteriolar smooth muscle
- blood vessel constricted
- increased vascular resistance
- decreased blood flow

56
Q

What is the difference between apex and base of lung

A

Apex: ventilation > perfusion

Base: perfusion > ventilation

57
Q

What is CO2 excretion associated with

A

H+ elimination

58
Q

What happens when CO2 excretion and H+ elimination increases

A

Arterial PCO2 decreases

59
Q

What factors affect amount of O2 carried by Hb

A

Partial pressure of O2 (PO2) in blood

Concentration of Hb in blood

pH

Temperature

2,3-diphosphoglycerate (2,3-DPG)

60
Q

When partial pressure of O2 (PO2) increases in blood, what happens to O2 binding to Hb

A

Increased O2 binding to Hb up till saturation capacity of Hb

61
Q

What is oxygenation

A

When each Fe atom binds reversibly to one O2 molecule

62
Q

The transport of O2 to tissues are dependent on

A

CVS, Blood, Respiratory system

63
Q

How is O2 transported in the blood

A

98% bound to Hemoglobin (Major carrier)

2% dissolved in plasma

64
Q

Which O2 exerts partial pressure in blood

A

O2 dissolved in plasma

65
Q

How is CO2 transported in the blood

A

7% dissolved in plasma

23% bound to proteins including Hb and forms carbamino compounds

70% converted to bicarbonate ion

66
Q

What enzyme converts CO2 to H2CO3

A

Carbonic anhydrase

67
Q

Why should we measure forced expiratory volumes of the lungs

A

Detects changes in airway resistance & elasticity of lungs

68
Q

What does FVC mean

A

Forced vital capacity

69
Q

What does FVC measure

A

Total volume expired forcefully after full inspiration

70
Q

What does FEV1 mean

A

Forced expiratory volume of air exhaled in 1 sec after full inspiration

71
Q

What hormones simulates production of 2,3-DPG

A

Epinephrine, Growth Hormone, Thyroid hormone

72
Q

What is 2,3-DPG

A

A by-product of RBC glycolysis

73
Q

How can O2 be released quicker

A

Increased 2,3-DPG

Increased temperature

Decreased pH

74
Q

When temperature increases, what happens to the sigmoidal curve

A

Shifts to the right

75
Q

When temperature decreases, what happens to the sigmoidal curve

A

Shifts to the left

76
Q

When pH increases, what happens to the sigmoidal curve

A

Shifts to the left

77
Q

When pH decreases, what happens to the sigmoidal curve

A

Shifts to the right

78
Q

When 2,3-DPG increases, what happens to the sigmoidal curve

A

Shifts to the right

79
Q

When 2,3-DPG decreases, what happens to the sigmoidal curve

A

Shifts to the left

80
Q

What is formed when Co2 binds to Hb

A

Carbamino Hb

81
Q

What is formed when H+ binds to Hb

A

HHb

82
Q

What is the function of HHb

A

Buffer pH

83
Q

What is the purpose of bicarbonate ion swapping out for Chloride ion

A

Shift maintains electrical neutrality

84
Q

What does compliance mean

A

The measure of stretchability

Change in lung vol/unit change in airway pressure

85
Q

What does decreased compliance of the lung mean

A

There is decreased stretchability and more work is needed for breathing

86
Q

what is the causes of decreased compliance

A

fibrosis, lack of surfactant, edema of alveolar walls

87
Q

What are the factors that influence the diffusion of gases

A

Difference in partial pressure of gases between alveoli & blood

Diffusion barrier

Area available for diffusion

Different properties of gases

88
Q

If the pressure difference increases, does the diffusion increase?

A

Yes

89
Q

If the diffusion barrier is thicker, what happens to the diffusion

A

Slower diffusion

90
Q

If the area available for diffusion decreases, what happens to the diffusion

A

diffusion decreases

91
Q

the greater the solubility in blood, the greater the diffusion?

A

Yes

92
Q

Is the diffusion of Co2 > o2?

A

Yes

93
Q

How does high altitude influence diffusion

A

Decreased difference in partial pressure causes decreased diffusion

94
Q

How does fibrosis and edema influence diffusion

A

Abnormal thickening of alveolar-capillary border = decreased diffusion

95
Q

How does pneumonia influence diffusion

A

Decreased alveolar volume/number of functional alveoli = decreased surface area for diffusion

96
Q

Does increased blood flow mean greater gas exchange?

A

No. One could have decreased alveoli with thickened membranes which negates this. Another could be exercise where there is increased blood flow but less time for gas to equilibrate

97
Q

what is the purpose of surfactant

A

decrease alveolar surface tension by lowering surface tension proportionally

98
Q

what is surfactant made of

A

lipids, proteins, phospholipids

99
Q

What does a lack of surfactant lead to

A

Alveoli collapse such as infant respiratory distress syndrome in newborns

100
Q

What can surfactant be found

A

along the surface of alveolar epithelium

101
Q

Why is surface tension not constant

A

alveoli of different diameters cannot coexist due to instability and air will flow from one to another and not the other way

102
Q

what is the major determinant of compliance of lungs

A

surface tension of alveoli

103
Q

what is the issue of smaller alveoli

A

greater tendency to collapse

104
Q

Does reducing tension lead to increased compliance

A

Reducing tension = reducing pressure = increased compliance

105
Q

What contributes to increased resistance by airway narrowing

A

Decreased lung volume

mucus accumulation

bronchoconstriction (contraction of smooth muscles of bronchioles)

106
Q

What are the sources of airway resistance

A

trachea, bronchi, bronchioles

107
Q

What are the factors of bronchodilation

A

Hormones - epinephrine

sympathetic simulation - minimal effect

increased co2 concentration - local chemical control

108
Q

what are the factors of bronchoconstriction

A

pathological - allergy induced spasm of airway. histamine, slow reactive substance of anaphylaxis (leukotrieves)

physiological - parasympathetic stimuli, decreased CO2 concentration (local chemical control)

Physical blockage of airway - airway collapse, edema of walls, excess mucus

HSC1007 (18 decks)

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