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PHGY210 > Respiratory > Flashcards

Respiratory Flashcards

1
Q

Where does gas exchange happen?

A

Occurs in the lungs

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2
Q

Inspiration

A

O2 inhaled in lungs

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3
Q

Expiration

A

CO2 exhaled from lungs

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4
Q

How is O2 and CO2 transported?

A

By the blood

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5
Q

Divisions of the trachea

A

divides into 2 main bronchi (lobar and segmental)

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6
Q

Smallest airways without alveoli are

A

the terminal bronchioles

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7
Q

Purpose of air inhaling air through the nose

A

cleans air of large dust particles

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8
Q

Parts of the nose where air passes through

A

nasal septum and nasal turbinates

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9
Q

Properties of right bronchi

A

3 lobar bronchi, 3 lobes

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10
Q

Properties of left bronchi

A

2 bronchi, 2 lobes

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11
Q

Pleura

A

Thin cellular sheet attached to thoracic cage interior and, the lung surface

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12
Q

parietal pleura

A

thoracic cage interior

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13
Q

visceral pleura

A

lung surface

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14
Q

What do the visceral pleura and parietal pleura form?

A

two enclosed pleural sacs (one around each lung) in thoracic cage

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15
Q

pneumothorax

A

collapsed lung

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16
Q

Two zones of the airways

A

conducting and respiratory

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17
Q

What does the conducting airways consist of?

A

mouth and nose opening down to the terminal bronchioles

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18
Q

What do the respitory airways consist of?

A

begins where the terminal bronchioles divide into respitory bronchioles

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19
Q

The smallest physiological unit of the lungs

A

the acinus

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20
Q

Which zone makes up most of the lungs due to abundant branching of the airways

A

Respiratory Zone

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21
Q

Does the conducting zone contribute to gas exchange? why?

A

Does not contribute to gas exchange

compose the anatomical dead space

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22
Q

What is beyond the respitory bronchioles?

A

alveolar ducts lined with alveoli

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23
Q

what region is the site of gas exchange

A

alveolar region

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24
Q

4 main functions of the conducting airways

A

Defense against bacterial infection/foreign particles

Warm and moisten inhaled air.

Sound and speech are produced by the movement of air passing over the vocal cords.

Regulation of air flow: smooth muscle around the airways may contract or relax to alter

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25
Q

Functions of the Respiratory zone

A

Site of gas exchange between the air in alveoli and the blood in pulmonary capillaries

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26
Q

The approximate number of alveoli and capillaries in body

A

300 million each will 1000 capillaries

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27
Q

Two lung circulations

A

Pulmonary and Bronchial circulation

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28
Q

Pulmonary circulation

A

Brings mixed venous blood that comes from different body organs to the lungs

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29
Q

Bronchial circulation

A

Supplies oxygenated blood from the systematic circulation to the tracheobronchial tree

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30
Q

Supply blood to all capillaries

A

Pulmonary arteries

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31
Q

three alveolar cell types

A

Epithelial type i and ii cells
Endothelial cells
Alveolar macrophages

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32
Q

Epithelial type i and ii cell

A

Alveoli are lined by epithelial type I and II cells

Form the epithelial layer sealed by tight junctions

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33
Q

Epithelial type ii cells

A

Produce pulmonary surfactant

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34
Q

pulmonary surfactant

A

Substance that decreases the surface tension of alveoli

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35
Q

Endothelial cells

A

Constitute the walls of the pulmonary capillaries (0.1 um thin)

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36
Q

Alveolar macrophages

A

Remove foreign particles that escaped the mucocilary defence system of the airways and found their way into the alveoli

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37
Q

How does the surface tension arise of the liquid film lining the lungs

A

Tension arises because the surface molecules tend to arrange themselves in the configuration wth lowest energy

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38
Q

Laplace‘s law

A

P=4T/R

Shows that the pressure inside a small bubble is greater than that inside a large bubble.

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39
Q

Why is expiration passive during quiet breathing

A

recoil of lungs/chest wall

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40
Q

When does expiration become active

A

at high levels of ventilation (exercise), or in pathological states when expiratory resistance increases while movement of airflow out of the lungs is impeded

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41
Q

Muscles involved in active expiration

A

internal intercostal muscles and abdominal muscles

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42
Q

What does the contraction of the abdominal muscles do?

A

compress the abdominal content, depress the lower ribs, and pull down the anterior lower chest
They force the diaphragm upwards

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43
Q

Why is forcing the diaphragm upwards essential?

A

Essential for coughing, singing, talking, vomiting

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44
Q

The main inspiratory muscle

A

diaphragm

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45
Q

What is the diagphragm inervated by

A

phrenic nerves from cervical segments 3, 4, 5

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46
Q

Contraction of the diaphragm causes

A

its dome to descend and the chest to expand longitudinally

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47
Q

What happens to the chest when the ribs are elevated?

A

the anterior-posterior and transverse dimensions of the chest enlarge

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48
Q

What muscles can also assist in inspiration? What conditions?

A

the external intercostal muscles and the parasternal inter- cartilaginous muscles, the neck muscles (sternocleidomastoid and
scalenes muscles)

during high levels of ventilation as well as severe asthma and other disorders that obstruct the movement of air into the lungs

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49
Q

What do the neck muscles do in inspiration?

A

The neck muscles elevate and fix the uppermost part of the rib cage, elevate the sternum and slightly enlarge the posterior and longitudinal dimensions of the chest

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50
Q

Spirometry

A

Useful clinical tool in order to measure the volume of air inhaled under a different circumstances

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51
Q

Spirometer

A

Measures volumes of inhaled

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52
Q

What can the spirometer measure?

A

tidal volume, vital capacity, inspiratory capacity, expiratory reserve volume, and inspiratory reserve volume

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53
Q

What can’t the spirometer measure?

A

functional residual capacity, total lung capacity or residual volume

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54
Q

Tidal Volume

A

amount of air inhalded or exhaled in one breath

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55
Q

Residual Volume

A

Air remaining in lungs after one expiration, keeps alveoli inflated between breaths and mixes with fresh air on next inspiration

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56
Q

Functional residual capacity

A

Air remaining in the lungs after a normal tidal expiration

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57
Q

Total lung capacity

A

maximum air of the lungs

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58
Q

How can the FRC (Functional Residual Capacity) be measured

A

helium dilution

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59
Q

helium dilution steps

A

C1 = helium concentration in a spirometer of volume V1 and let the subject breath out to FRC

Open the valve and ask the subject to breath in and out from the spirometer

After equilibrium with the subjects lungs, the concentration in the spirometer is C2

Equation: C1 x V1 = C2 x (V1 + FRC) so that: FRC = (C1 x V1 /C2) - V1

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60
Q

ventilation

A

The amount of air inspired into the lungs over some period of time

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61
Q

minute ventilation

A

The amount of air inspired into the lungs over a minute

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62
Q

The formula for minute ventilation

A

tidal volume * number of breaths per minutes

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63
Q

Normal Adult male minute ventilation

A

VT = 500 mL; f = 12 breaths / min; VE = 6000 ml/min

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64
Q

Does all of the air inhaled to reach the respiratory zone?

A

Not all air inhaled into the lungs reaches the gas exchanging area (the respitory zone)

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65
Q

Why does not all air reach the respiratory zone?

A

Some air remains in conducting airways (anatomical dead space)

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66
Q

the alveolar ventilation (VA)

A

The amount of air that reaches the respiratory zone per minute

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67
Q

Average VA

A

4200 ml/min

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68
Q

The volume of the anatomical dead space

A

150 mL

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69
Q

Physiological Dead Space

A

inspired air that reaches the respiratory zone and does not take part in the gas exchang

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70
Q

Why is there physiological Dead Space represented by alveolar dead space

A

Due to alveoli either receiving a decreased blood supply or no blood supply at all

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71
Q

Physiological dead space (VD) is the sum of

A

alveolar and anatomical dead space

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72
Q

The difference between minute and alveolar ventilation is

A

the dead space ventilation that is wasted from gas exchange point of view

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73
Q

What keeps at artierial PaCO2 at a constant level

A

alveolar ventilation

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74
Q

PO2 of Air

A

160 mmHg

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75
Q

PCO2 of Air

A

0.3 mmHg

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76
Q

PO2 of alveoli

A

105 mmHg

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77
Q

Pco2 of alveeoli

A

40 mmHg

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78
Q

PO2 in pulmonary veins

A

100

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79
Q

PO2 of systemic artieries

A

100

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80
Q

PCO2 in pulmonary veins

A

40

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81
Q

PCO2 of systemic artieries

A

40

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82
Q

PO2 in cells

A

<40 mmHg (mitochondrial Po2 <5 mmHg)

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83
Q

PCO2 in cells

A

> 46 mmHg

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84
Q

PO2 in systemic veins

A

40

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85
Q

PCO2 in systemic veins

A

46

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86
Q

PO2 in pulmonary arteries

A

40

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87
Q

PCO2 in pulmonary arteries

A

46

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88
Q

Alveolar hyperventilation

A

When more O2 is supplied and more CO2 is removed than the metabolic rate requires (VE exceeds needs of body)

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89
Q

Is ventilation during excersise considered hyperventilation? why?

A

ventilation has to be considered with respect to metabolism so ventilation during exercise is not

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90
Q

How are the PACO2 and PAO2 affected during hyperventilation

A

Results in alveolar partial pressure of O2

(PAO2) rises and CO2 (PACO2) decreases

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91
Q

Alveolar hypoventilation

A

Fall in overall level of ventilation —> reduce alveolar ventilation below that required by the metabolic activity of the body

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92
Q

How are the PACO2 and PAO2 affected during hypoventilation

A

PAO2 falls and PACO2 rises

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93
Q

Is the blood in the pulmonary capillary more or less oxygenated?

A

The blood in the pulmonary capillary is less oxygenated

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94
Q

Why can Alveolar hypoventilation occur?

A

May occur during severe disorders of the lungs (chronic obstructive lung disease) or when there is damage to the respitory muscles; also when the chest cage is injured and lungs collapse or when the CNS is depressed

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95
Q

Affect on Alveolar PO2 and PCO2 when breathing air with low PO2

A

PO2 decreases

PCO2 no change

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96
Q

Affect on Alveolar PO2 and PCO2 when alveolar ventilation increases and unchanged metabolism

A

PO2 increases

PCO2 decreases

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97
Q

Affect on Alveolar PO2 and PCO2 when alveolar ventilation decreases and unchanged metabolism

A

PO2 decreases

PCO2 increases

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98
Q

Affect on Alveolar PO2 and PCO2 when metabolism increases and alveolar ventilation unchanged

A

PO2 decreases

PCO2 increases

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99
Q

Affect on Alveolar PO2 and PCO2 when metabolism decreases and alveolar ventilation unchanged

A

PO2 increases

PCO2 decreases

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100
Q

Affect on Alveolar PO2 and PCO2 when proportional increases in metabolism and alveolar ventilation

A

PO2 no change

PCO2 no change

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101
Q

Oxygen from the alveolar gas must be transferred across the alveolar-capillary membrane for ventilation by

A

passive diffusion

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102
Q

What is passive diffusion governed by

A

Fick’s Law

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103
Q

Fick’s Law

A

Rate of diffusion of a gas through a tissue is

  • Proportional to the tissue area and the difference in gas partial pressure between the 2 sides
  • Inversely proportional to the tissue thickness
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104
Q

Diffusion rate is proportional to

A

surface area
partial pressure gradient
1/thickness

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105
Q

What direction is diffusion

A

Diffusion direction is from higher to lower pressure

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106
Q

How does O2 and CO2 diffuse in the alveolar and blood

A

O2 diffuses from the alveolar gas to the blood, and

CO2 diffuses in the opposite direction

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107
Q

What must the gas be in order to diffuse through a liquid?

A

the gas must be soluble in the liquid

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108
Q

Solubility of CO2 vs O2

A

CO2 is more soluble than O2 (diffuses 20 times more rapidly than O2)

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109
Q

difference between PO2 on either side of the alveolar-capillary membrane

A

At the beginning of the pulmonary capillaries there is a large difference between PO2 on either side of the alveolar-capillary membrane.

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110
Q

the O2 gradient between the blood and the lungs

A

large

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111
Q

How does the O2 gradient change with time as blood flows through the lung capillaries?

A

smaller

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112
Q

By the end of the capillary, as more O2 has moved from the lungs to the blood, how does the O2 gradient and rate of diffusion change?

A

O2 gradient becomes less

the rate of diffusion must decrease (due to a smaller pressure gradient)

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113
Q

At the beginning of the capillaries, what is the PCO2

A

46

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114
Q

what is the PCO2 in the alveolar gas

A

40

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115
Q

The difference in PCO2 and PO2 between the 2 sides of the alveolar-capillary membrane is

A

10 times smaller than that for PO2

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116
Q

The time required for equilibrium between alveolar air and capillary blood is

A

approximately the same for the two gases.

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117
Q

the transit time of blood through the pulmonary capillaries is

A

only 0.75 seconds at rest

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118
Q

Times of diffusion for both O2 and CO2 compared to the red blood cell transit time

A

1/3 time

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119
Q

condition of a resting person with an impaired rate of diffusion

A

a patient with pulmonary edema

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120
Q

PCO2 and PO2 of a resting person with an impaired rate of diffusion

A

in a resting person with an impaired rate of diffusion PO2 and PCO2 may be normal (because CO2 and O2 may still be able to diffuse during the transit time).

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121
Q

when blood flow increases in this person and the transit time consequently becomes shorter (during exercise). What is the affect on arterial PO2 and PCO2

A

arterial PO2 may decrease and arterial PCO2 may increase

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122
Q

Blood pressure in the pulmonary circulation vs systemic circulation

A

Blood pressure in the pulmonary circulation is lower than in the systemic circulation

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123
Q

The walls of the pulmonary capillaries are thicker/thinner than those of similar vessels in the systemic circulation

A

thinner

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124
Q

Why are the pulmonary capillaries thinner than the systemic circulation vessels?

A

Less smooth muscle

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125
Q

The mean pulmonary arterial pressure

A

15 mmHg

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126
Q

Left atrial pressure

A

5 mmHg

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127
Q

Right Ventricle pressure

A

25

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128
Q

Left Ventricle pressure

A

120

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129
Q

The mean systemic arterial pressure

A

100

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130
Q

Blood flow depends on

A

vascular pressure and resistance

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131
Q

flow equation

A

pressure/resistance

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132
Q

pressure change from pulmonary artery to left atrium

A

from pulmonary artery to left atrium of about 10 mm Hg,

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133
Q

pressure change from systemic artery to right atrium

A

~100mmHg for the systemic artery to right atrium

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134
Q

Pulmonary vs systemic resistance

A

the pulmonary resistance is only 1/10 that of the systemic circulation

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135
Q

The low vascular resistance in the pulmonary circulation relies

A

the thin walls of the vascular system

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136
Q

The low vascular resistance/high compliance of the pulmonary circulation allows

A

the lung to accept the whole cardiac output at all times.

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137
Q

with little change in pulmonary arterial pressure the pulmonary circulation has the capacity to

A

accommodate two- to three-fold increases in cardiac output

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138
Q

The increase in blood flow with little changes in driving pressure indicates

A

that as pulmonary blood flow increases, pulmonary resistance falls

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139
Q

Blood vessels may do two things?

A

already perfused increase their caliber (distension), and previously closed vessels may open as the cardiac output rises (recruitment)

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140
Q

How does Drugs (serotonin, histamine, norepinephrine) affect smooth muscle and pulmonary vascular resistance?

A

cause the contraction of smooth muscle increase pulmonary vascular resistance in the larger pulmonary arteries.

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141
Q

How does Drugs (acetylcholine, isoproteranol) affect smooth muscle and pulmonary vascular resistance?

A

can relax smooth muscle may decrease pulmonary vascular resistance.

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142
Q

What is the reflex in regions of the lungs that are poorly oxygenated

A

a reflex vasoconstriction

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143
Q

Nitric oxide is produced by what cells

A

endothelial cells

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144
Q

What does nitric acid do to smooth muscle?

A

Nitric oxide produced by endothelial cells relaxes vascular smooth muscle leading to vasodilation

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145
Q

How is pulmonary blood flow affected by gravity?

A

it differs with body posture

In the upright position, blood flow increases almost linearly from top to bottom of the lungs

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146
Q

Why does blood flow increase from top to bottom of the lungs

A

The vessels are more distended toward the bottom of the lungs because gravity increases vascular pressure

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147
Q

How is distribution of blood flow in the upright human lung measured? what element?

A

using radioactive xenon. The dissolved xenon is evolved into alveolar gas from the pulmonary capillaries.

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148
Q

Why is there lower blood flow observed at the very very bottom of the lung?

A

due to some vessels being less expanded at low lung 47 volumes

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149
Q

What may happen at the top of the lungs, if alveolar pressure is greater than blood pressure in the capillaries?

A

Near the top of the lungs, the pulmonary capillaries may be completely compressed if alveolar pressure is greater than blood pressure in the capillaries

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150
Q

The hydrostatic pressure of the blood

A

the pressure due to the weight of the blood

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151
Q

The hydrostatic pressure of the blood affect on blood flow

A

The hydrostatic pressure of the blood (the pressure due to the weight of the blood) causes an uneven distribution of blood flow from the top to bottom of the lung

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152
Q

the lungs can be looked at as consisting of 3 zones

A

top, middle, bottom

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153
Q

Top zone pressures

A

pulmonary arterial pressure< alveolar pressure

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154
Q

Top zone capillaries

A

capillaries are compressed

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155
Q

When does top zone only occur?

A

Occurs only in cases of low arterial pressure or positive ventilation

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156
Q

Middle zone pressures

A

pulmonary arterial pressure> alveolar pressure > venous pressure

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157
Q

Bottom

A

pulmonary arterial pressure> venous pressure> alveolar pressure

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158
Q

Flow in bottom zone depends on

A

So the flow depends on the arterio-venous pressure difference

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159
Q

Flow in middle zone depends on

A

So the flow depends only on the difference between arterial and alveolar pressures

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160
Q

Does gravity affect the distribution of ventilation

A

yes

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161
Q

In an upright lung at rest, in normal gravity, the alveoli at the top vs bottom

A

In an upright lung at rest, in normal gravity, the alveoli at the top of the lungs are more opened than the bottom ones

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162
Q

preferential ventilation occurs at what parts of the lungs

A

the bottom of the lungs, the alveoli from the bottom of the lungs are opened wider than those at the top

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163
Q

How can the distribution of ventilation be measured?

A

a similar way as that of perfusion but with inhaled radioactive Xenon instead of infused in the blood
When the gas is inhaled, its radiation can be detected by counters outside the chest

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164
Q

Ventilation vs blood flow in the lung top to bottom?

A

Ventilation increases slowly from top to bottom of the

lung but blood flow increases more rapidly.

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165
Q

ventilation- perfusion ratio at the top of the lung vs the bottom

A

the ventilation- perfusion ratio is abnormally high at the top and much lower at the bottom.

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166
Q

VO2

A

O2 consumption per minute

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167
Q

CvO2

A

The [O2] in the blood entering the lungs

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168
Q

CaO2

A

The [O2] in the blood exiting the lungs

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169
Q

Where is CaO2 measured

A

measured from an artery

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170
Q

Where is CvO2 measured

A

measured via a catheter from the pulmonary artery

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171
Q

Does O2 dissolve in the plasma?

A

O2 dissolves in plasma

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172
Q

Why is O2 proportional to PO2

A

Because O2 is relatively insoluble in H2O, the amount of O2

dissolved in blood is very small

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173
Q

Henry’s Law

A

The amount of dissolved gas carried by the blood is directly proportional to the partial pressure of the gas

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174
Q

In 100 ml of plasma, ho2 much O2 is there? (ml)

A

0.3 ml when equilibrated with PO2 of 100 mmHg

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175
Q

What can we infer from henrys law about the # of gas molecules and the partial pressure of the gas

A

that the number of gas molecules dissolved in a liquid is proportional to the partial pressure of the gas above the liquid

176
Q

O2 consumption (VO2) by the body cells vs what can be supplied from the amount dissolved in blood

A

O2 consumption (VO2) by the body cells, even at rest, is much greater than what can be supplied from the amount dissolved in blood

177
Q

At rest, O2 is

A

300 ml O2/min

178
Q

What would happen if O2 were only found in plasma

A

the tissue demand for O2 would never be met

179
Q

What is O2 bound to?

A

O2 Bound to Hemoglobin

180
Q

Where is Hemoglobin found

A

Hemoglobin, Hb, is found in red blood cells

181
Q

total weight of red blood cells from hemoglobin

A

1/3

182
Q

Hb in each liter of blood

A

147g

183
Q

How much more O2 can be taken up by hemoglobin compared to plasma

A

65 times as much O2 as plasma

184
Q

Hb structure

A

Each molecule consists of 4 subunits bound together

185
Q

Hemoglobin subunit structure

A

Each subunit is made up of a heme joined to a globin

contains an Fe++ ion that can bind 1 molecule of O2

186
Q

an Fe++ ion can bind how many molecules of O2

A

1

187
Q

How many oxygens does hemoglobin bind to?

A

4

188
Q

Why is hemoglobin essential

A

for the transport of O2 by blood because it combines rapidly and reversibly with O2

189
Q

the total amount of O2 physically dissolved in the blood is?

A

0.3 vol.%,

190
Q

total amount of O2 bound to Hb is?

A

19.5 vol. %

191
Q

the total amount of O2 in arterial blood is about

A

20 vol. %

192
Q

Do the O2 that is bound to Hb contribute to the PO2 of the blood?

A

No,

the O2 that is bound to Hb does not contribute to the PO2 of the blood

193
Q

What molecules are responsible for PO2?

A

Only molecules

physically dissolved in the blood plasma are responsible for PO2

194
Q

How does the PO2 of the plasma affect Hb?

A

the PO2 of the plasma does determine the amount of O2 that combines with Hb`

195
Q

The HbO2 dissociation curve determines

A

determines the amount of O2 carried by Hb for a given partial pressure of O2

196
Q

The HbO2 dissociation curve key results

A

The curve is flat at high values of PO2 (at alveolar levels of PO2) and steep at low values of PO2 (at peripheral tissue levels of PO2)

197
Q

At low values of PO2, how does a small drop in PO2 affect O2?

A

a small drop in PO2 unloads the O2 from Hb to the tissue

198
Q

HbO2 dissociates into Hb and O2 more readily at what PO2 levels?

A

lower

199
Q

at the tissue level, PO2 may get as low as

A

1-3 mmHg

200
Q

As blood enters the tissue capillaries, how does plasma PO2 compare to interstitial fluid PO2?

A

As blood enters the tissue capillaries, plasma PO2 is greater than interstitial fluid PO2

201
Q

Does O2 readily diffuses across the capillary membrane into the interstitial fluid?

A

Yes

202
Q

What does the diffuse of O2 across the capillary membrane do to the PO? how does this affect Hb dissociation?

A

This lowers plasma PO2, and O2 diffuses out of the erythrocytes into the plasma
The lowering of erythrocyte PO2 causes the dissociation of HbO2 into Hb and O2

203
Q

What percentage of Hb is saturated under resting conditions?

A

Under resting conditions, Hb is still 75% saturated at the end of the tissue capillaries

204
Q

myoglobin

A

function is to act as an intracellular carrier which facilitates the diffusion of oxygen throughout the muscle cell

205
Q

What determines Hbs affinity for O2

A

The quaternary structure of Hb determines its affinity for O2

206
Q

cooperative binding in Hb and O2

A

The combination of the first heme in Hb with O2 increases the affinity of the second heme for O2

207
Q

Is myoglobin similar to hemoglobin? differences?

A

yes, Myoglobin, resembles Hb but binds only one O2 molecule.

208
Q

Shape of O2- myoglobin curve

A

hyperbolic in shape. myoglobin will release its O2 only at very low PO2

209
Q

The total amount of O2 in the blood depends mostly on

A

Hb concentration

210
Q

anaemia

A

conditions of decreased Hb concentration

211
Q

The Bohr Effect

A

The Bohr Effect is the shift of the HbO2 dissociation curve to the right when blood CO2 or temperature increases or blood pH decreases

212
Q

What happens to CO2, acid production and heat, as we exercise?

A

when we exercise, we increase our CO2 and acid production and generate heat

213
Q

How is the amount of O2 released affected by the curve shifting to the right means that for a given drop in PO2?

A

an additional amount of O2 is released from Hb to the working tissues

214
Q

when 2,3- diphosphoglycerate (2,3-DPG), increases how does this affect the amount of O2 released?

A

an additional amount of O2 is released from Hb to the working tissues

215
Q

2,3- diphosphoglycerate

A

an end product of red blood cell metabolism,

216
Q

2,3-DPG levels may increase during what disease? conditions?

A

chronic hypoxia

high altitude or lung disease

217
Q

How do a decrease in temperature, an increase in pH, and a decrease in CO2 affect the dissociation curve?

A

opposite effect on the dissociation curve, shifting it to the left

218
Q

Do these factors, such as temperature and PH have a large affect on the total amount of O2 combines with Hb over 80 mmHg?

A

all of these factors, have little effect on the total amount of O2 combined with Hb above 80 mm Hg

219
Q

Affinity of CO on hemoglobin

A

CO has an extremely high affinity for the O2 binding sites in hemoglobin (210-fold)

220
Q

Carbon monoxide poisoning affect on bound O2

A

it reduces the amount of O2 bound to hemoglobin

221
Q

Carbon monoxide poisoning shift on O2-hemoglobin curve

A

left decreasing the unloading of O2 to the tissue

222
Q

How is the stimulation to increase ventilation affected in CO poisoning?

A

In CO poisoning, there is little stimulation to increase ventilation because PaO2 remains normal

223
Q

the primary product of the oxidative processes taking place in the body cells

A

CO2

224
Q

How is CO2 removed from the tissues

A

blood

225
Q

How much O2 does a person use at rest?

A

300 ml/min

226
Q

How much CO2 does a person produce at rest?

A

250 ml/min

227
Q

How does O2 use and CO2 production change during heavy exercise?

A

can go up twenty time during heavy exercise

228
Q

Forms that CO2 can be carried in

A

Physically dissolved in blood
Combined with Hb to form HbCO2
As bicarbonate

229
Q

% of CO2 Physically dissolved in blood

A

10

230
Q

% of CO2 Combined with Hb to form HbCO2

A

11

231
Q

% of CO2 As bicarbonate

A

79

232
Q

CO2 physically dissolves in the blood by which law

A

According to Henry’s Law, CO2 from the tissues diffuses into the plasma where it is physically dissolved.

233
Q

Which portion of the hemoglobin does CO2 combine with

A

Contrary to O2 that combines with the heme portion of Hb, CO2 combines with the globin portion

234
Q

Is there compition for binding on Hb from O2 and CO2

A

there is no competition for binding on Hb.

Contrary to O2 that combines with the heme portion of Hb, CO2 combines with the globin portion

235
Q

How is CO2 produced in bicarbonate form?

A

CO2 combines with H2O to produce carbonic acid (H2CO3)

236
Q

Bicarbonate reaction in plasma speed

A

This reaction is very slow in plasma

237
Q

How is the Bicarbonate reaction sped up

A

the reaction is aided by the enzyme carbonic anhydrase (CA)

238
Q

Are the bicarbonate reactions reversible?

A

All these reactions are reversible, so they can proceed in either direction, depending upon the prevailing conditions

239
Q

If CO2 production increases, the production of HbCO2, HCO3-, and H+

A

increases

240
Q

Lowering of blood PCO2 affect on HCO3- and HbCO2

A

HCO3- getting transformed into H2CO3 and further into CO2 and H2O, and HbCO2 generating Hb and CO2.

241
Q

In what vessels does HCO3- getting transformed into H2CO3 and further into CO2 and H2O, and HbCO2 generating Hb and CO2.

A

This situation occurs when venous blood flows through the lung capillaries

242
Q

The Haldane Effect

A

that mixed venous blood can carry more CO2 than can arterial blood.

243
Q

The presence of reduced Hb in the tissue capillaries helps with what?

A

with the blood loading of CO2

244
Q

The O2 saturation of blood influences the CO2 dissociation curve by shifting it to the

A

right

245
Q

as Hb unloads O2 into the tissues, it is able to take up CO2 in what amounts?

A

take up increased amounts of CO2 from the tissues

246
Q

for a given PCO2, how does CO carried in deoxygenated blood compare with in oxygenated blood

A

for a given PCO2, more CO2 is carried in deoxygenated blood than in oxygenated blood

247
Q

In the tissue capillaries, Hb free of O2, can combine with what? reaction

A

may combine with H+, in the reaction:

H+ + HbO2 -> HHb +O2

248
Q

Why does H+ combine with Hb that isn’t with O2?

A

occurs because reduced Hb
is less acidic than HbO2
Hb acts as a buffer

249
Q

How does a sudden lowering of blood PCO2, affect the HCO3- and HbCO2 levels? where does venus blood flow

A

esults in HCO3- going to H2CO3 and further into CO2 and H2O, and HbCO2 generating Hb and CO2

venous blood flows through the lung capillaries

250
Q

Unlike the HbO2 curve, the CO2 dissociation curve

A

has no steep or flat portions

251
Q

the relationship between CO2 content and PCO2

A

the relationship between CO2 content and PCO2 is almost linear.

252
Q

if we hypoventilate and alveolar PCO2 rises, how is the arterial, capillary, tissue, and venous CO2 affected?

A

then arterial, capillary, tissue and venous CO2 also rise

253
Q

Doubling alveolar ventilation affect on alveolar PCO2? what does this conclude?

A

halves alveolar PCO2

follows that an increase in alveolar ventilation proportionally increases CO2 removal

254
Q

Respiratory Failure

A

occurs when the respiratory system is unable to do its job properly

255
Q

3 reasons respiratory failure can occur

A

the gas exchanging capabilities of the lungs

the neural control of ventilation (i.e. the drive to breathe)

the neuromuscular breathing apparatus (i.e. the respiratory muscles and their innervation

256
Q

Blood hypoxia

A

deficient blood oxygenation

i.e. low PaO2 and low % Hb saturation

257
Q

In hypoxic conditions, if PaO2 decreases below 60 mm Hg, O2 content in arterial and venous blood is affected how?

A

becomes lower than the normal values at sea level

258
Q

5 general causes of hypoxia:

A
  1. Inhahlation of low PO2 (e.g. at high altitude).
  2. Hypoventilation
  3. Ventilation/perfusion imbalance in the lungs
  4. Shunts of blood across the lungs
  5. O2 diffusion impairment
259
Q

Hypoventilation occurs due to:

A

diseases affecting the CNS, neuromuscular diseases, barbiturates, other drugs

260
Q

Ventilation/perfusion imbalance in the lungs occurs when

A

the amount of fresh gas reaching an alveolar region per breath is too little for the blood flow through the capillaries of that region

261
Q

Shunts of blood across the lung occurs when? example

A

venous blood bypasses the gas exchanging region of the lungs and returns to systemic circulation, deoxygenated. Example: foramen ovale.

262
Q

O2 diffusion impairment example

A

thickening of the alveolar-capillary membrane, or pulmonary edema

263
Q

automatic breathing

A

involuntary activity that brings enough air into the pulmonary alveoli to maintain the O2 and CO2 tensions of alveolar gas or arterial blood at optimal levels in different conditions

264
Q

When does automatic breathing occur

A

During sleep, rest, or exercise

265
Q

Is breathing under voluntary or involuntary control?

A

Under both voluntary and involuntary control

266
Q

What neurological structure controls voluntary breathing?

A

The cerebral hemisphere

267
Q

What neurological structure controls involuntary breathing?

A

Brainstem

268
Q

Are the involuntary and voluntary control two separate neurological structures?

A

Anatomically, there are separate neurological structures for automatic and voluntary control, although the two systems interact

269
Q

How does the CNS affect breathing?

A

The CNS controls gas exchange by integrating all the information coming from the periphery: gives an adequate depth and frequency of breathing (minute ventilation)

270
Q

If automatic control no longer functions, what will happen to voluntary breathing?

A

Can be effective even when automatic control no longer functions

271
Q

Breaking Point (PCO2, PO2)

A

point voluntary control is over-ridden

occurs because the arterial PCO2 has reached about 50 mm Hg and arterial PO2 has reached about 70 mm Hg

272
Q

The over-riding of the voluntary control by the automatic control depends upon

A

the information from the receptors sensitive to CO2 and O2 levels (in arterial blood and/or cerebro-spinal fluid)

273
Q

What parts of the brainstem are involved in the involuntary control of breathing

A

pons and medulla

274
Q

3 elements in respiratory control system

A

Sensors, controllers, effectors

275
Q

Sensors

A

these gather information about lung volume (pulmonary receptors) and O2 and CO2 content (chemoreceptors)

276
Q

Controllers

A

information from the sensors is sent to the controller, in the pons and medulla, via afferent neural fibers. Once it has reached the
pons and medulla, the peripheral information and inputs from the higher structures of the central nervous system are integrated

277
Q

Effectors

A

neuronal impulses are generated and sent via spinal motoneurons to the effectors, i.e. the respiratory muscles.

278
Q

Has pacemaker cells

A

Medulla

279
Q

Pacemaker cells are located in how many groups? names?

A

mainly located in two groups of cells

ventral respiratory group and dorsal respiratory group

280
Q

Dorsal respiratory group

A

Receives several sensory inputs

281
Q

ventral respiratory group

A

generate the basic rhythm

282
Q

Respiratory neurons in the medulla generate

A

the basic respiratory rhythmicity

283
Q

Where are the upper pons located?

A

cells located in the rostral (upper) pons

284
Q

rostral (upper) pons is known as

A

called the pneumotaxic center

285
Q

What do the pons do?

A

modify the inspiratory activity of the centers in the medulla

286
Q

Which cells “turn off” inspiration leading to smaller tidal volume?

A

pons

287
Q

what does “turn off” inspiration lead to ?

A

smaller tidal volume which leads to an increase in breathing frequency to maintain adequate alveolar ventilation

288
Q

What does cutting the pneumotaxic centers cause?

A

breathing to become deep and slow

289
Q

Where are the lower pons cells located?

A

lower pons

290
Q

What are the the lower pons called?

A

the apneustic center

291
Q

What do the lower pons do?

A

send exicitatory impulses to the respiratory groups of the medulla

292
Q

What does excitatory impulses to the respiratory groups of the medulla promote?

A

inspiration

293
Q 
Match the following:
upper pons, lower pons, medulla
- promote inspiration
- rhythm
- turn-off inspiration
A

upper pons- turn-off inspiration
lower pons- promote inspiration
medulla - rhythm

294
Q

Removing the influence of both the upper pons and the vagus nerves causes

A

apneuses

295
Q

apneuses

A

tonic inspiratory activity interrupted by short expirations

296
Q

What does chemoreceptors detect in the blood?

A

Detect PO2, PCO2, and pH in arterial blood

297
Q

If the PO2, PCO2, and pH in arterial blood change, what will occur?

A

ventilation will change to return the gas pressures to their normal values

298
Q

The information from chemorecptors is carried to?

A

respiratory neurons

299
Q

At what levels of PaO2 and PaCO2 do the activity of respiratory neurons increase

A

PaO2 is to low <60

PaCO2 is to high >40

300
Q

At what levels of PaO2 and PaCO2 do the activity of respiratory neurons decrease

A

PaO2 is to high >100

PaCO2 is to low <40

301
Q

Two types of chemoreceptors

A

central and peripheral

302
Q

Where are central chemoreceptors located?

A

the ventral surface of the medulla

303
Q

Where do central chemoreceptors detect?

A

the pH of the cerebrospinal fluid that is around them

304
Q

PCO2 and pH of the CSF are influenced by

A

Those of arterial blood

305
Q

What gives rise to the main drive to breathe under normal conditions?

A

central chemoreceptors

306
Q

The sensitivity of these central chemoreceptors may be easily assessed by

A

a CO2 rebreathing test

307
Q

What occurs in the a CO2 rebreathing test

A

subject breathe different CO2 mixtures, or rebreathe expired air from a bag filled with O2 so that with each expiration, the inspired PCO2 gradually increases

308
Q

How does hyperventilation affect PCO2 in the blood and CSF

A

hyperventilation reduces PCO2 in the blood, and therefore in the CSF.

309
Q

Stimulation of the chemoreceptors increases

A

minute ventilation

310
Q

What are central chemoreceptors bathed in? why?

A

They are bathed in brain extracellular fluid (ECF)

through which CO2
easily diffuses from the blood vessels to cerebrospinal fluid (CSF).

311
Q

What reduced the CSF pH? what does this stimulate?

A

The CO2 reduces the CSF, thus stimulating the chemoreceptor.

312
Q

Can H+ and HCO3- easily cross the blood-brain barrier?

A

no

313
Q

How do small increases in PCO2 affect minute ventilation, respiratory rate, and tidal volume?

A

Small increases in PCO2, increase minute ventilation (left) due to an increase in respiratory rate (center) and tidal volume (right).

314
Q

hypercapnia

A

elevated CO2 in blood

315
Q

What are Peripheral Chemoreceptors sensitive/ stimulated by?

A

are mainly sensitive to changes in PO2, but are also stimulated by
increased PCO2 and decreased pH

316
Q

Where are Peripheral Chemoreceptors located in?

A

located in the carotid bodies (i.e. the bifurcation of the common carotid arteries) and in the aortic bodies (next to the ascending aorta)

317
Q

Where do the afferent fibers of the peripheral chemoreceptors project?

A

the afferent fibers of these receptors project to the dorsal group of respiratory neurons in the medulla

318
Q

What are the carotid and aortic bodies made up of?

A

blood vessels, structural supporting tissue, and numerous nerve endings of sensory neurons of the glossopharyngeal (in carotid bodies, IX nerve) and vagus nerves (in aortic bodies, X nerve)

319
Q

The effects of hypoxia on ventilation can be studied by

A

having a subject breathe gas mixtures with decreased concentrations of O2

320
Q

When do changes in minute ventilations occur? PO2 levels?

A

During normocapnia (normal levels of CO2 in blood), the alveolar PO2 can be reduced to about 60 mm Hg before appreciable changes in minute ventilation occur

321
Q

at increased PCO2, a decrease of PO2 below 100 mmHg results in

A

can already cause an increase in minute ventilation

322
Q

Pulmonary Vagal Receptors

A

Afferent fibres from all of these receptors travel in the vagus nerves. If the vagus nerve is sectioned, the result is slow, deep breathing

323
Q

Three types of receptors in the lungs that respond to mechanical stimuli

A

Pulmonary Stretch Receptors, Irritant Receptors, Juxta-capillary or J receptors (C-fibres)

324
Q

Where are Pulmonary Stretch Receptors located?

A

located in smooth muscles of the trachea down to the terminal bronchioles

325
Q

What are pulmonary stretch receptors innervated by? what do they discharge in response to?

A

innervated by large, myelinated fibres, and they discharge in response to distension of the lung

326
Q

How is the Pulmonary Stretch Receptors activity sustained?

A

as long as the lung is distended

327
Q

How does the activity of these Pulmonary Stretch receptors change during each inspiration?

A

Activity of these receptors phasically increases as lung volume increases during each inspiration

328
Q

the Hering-Breuer Inflation Reflex

A

is a decrease in respiratory frequency due to a prolongation of expiratory time

329
Q

What is the main reflex effect of stimulating pulmonary Stretch receptors?

A

The main reflex effect of stimulating these receptors

330
Q

Where are Irritant Receptors located?

A

are located between airway epithelial cells in the trachea down to the respiratory bronchioles

331
Q

How are Irritant Receptors stimulated?

A

They are stimulated by noxious gases, cigarette smoke, histamine, cold air, and dust

332
Q

What are Irritant receptors innervated by? what does it result in?

A

innervated by myelinated fibers, and their stimulation leads to bronchoconstriction and hyperpnea (increased depth of breathing)

333
Q

What reflex are Irritant receptors important in? triggered by?

A

irritant receptors may be important in the reflex bronchoconstriction triggered by histamine release during an allergic asthmatic attack

334
Q

Where do the J receptors originate from?

A

these fibres originates from their location in the alveolar walls close to the capillarie

335
Q

What are J receptors innervated by?

A

innervated by non-myelinated fibres and have short lasting bursts of activity

336
Q

What are J receptors stimimulated by?

A

stimulated by an increase in pulmonary interstitial fluid, like what may occur in pulmonary congestion and edema

337
Q

What conditions might J receptors be stimulated by?

A

pulmonary congestion and edema

338
Q

The reflex effects caused by these receptors

A

include rapid and shallow respiration, although intense stimulation causes apnea

339
Q

What receptors may play a role in dyspnea?

A

J receptors associated with left heart failure and lung edema or congestion

340
Q

dyspnea

A

sensation of difficulty in breathing

341
Q

Pleural Space

A

The ventilatory apparatus consists of the lungs and the surrounding chest wall

342
Q

Importance of the lungs filling for visceral and partiental pleura

A

The lungs fill the chest so that the visceral pleura are in contact with the parietal pleura of the chest wall

343
Q

What does the chest wall include?

A

The chest wall includes not only the rib cage, but also the diaphragm and the abdominal wall

344
Q

Mechanically, how do the lung and chest wall act together

A

Operate in series with one another, but they are not directly attached together

345
Q

How are the viseral and pariental pleura coupled together?

A

The viseral and pariental pleura are coupled together by a thin layer of liquid that fills the intrapleural space

346
Q

What does the thin layer of liquid that fills the intrapleural space do?

A

Allows the lungs to slide against the internal wall of the chest during breathing and to follow the change in thoracic configuration

347
Q

Ppl

A

Pleural pressure

348
Q

Pleural pressure

A

pressure that can be measured in the liquid-filled space between lung and chest

349
Q

Pressure in the pleural space is positive/negative? why?

A

negative

due to the opposing forces acting on the lung and chest wall

350
Q

pneumothorax

A

if a hole is punctured through the chest wall, the lungs collapse and the chest springs outwards

351
Q

pneumothorax pressure

A

0, same as outside

352
Q

To evaluate the elastic properties of the respiratory system

A

we measure changes in the recoil pressure of each separate structure for a given change in lung volume by a spirometry

353
Q

Pressures are measured using

A

manometers or pressure transducer as reference to atmospheric pressure

354
Q

negative pressure

A

below atmospheric pressure

355
Q

positive pressure

A

above atmospheric pressure

356
Q

trans chest wall pressure

A

difference between Ppl and the pressure at the body surface

357
Q

recoil pressure of a structure

A

the pressure difference between the inside and outside of the structure (transmural pressure)

358
Q

How can Ppl be measured

A

a flexible balloon introduced into the esophagus, between the two pleural spaces

359
Q

What gives a close approximation of pleural pressure?

A

esophageal pressure

360
Q

The recoil pressure of the lungs

A

transpulmonary pressure (Pl)

361
Q

transpulmonary pressure (Pl) measured by? what requiredments?

A

the difference between Palv and Ppl

no air flow (closed nose and mouth)

362
Q

The recoil pressure of the total respiratory system

A

the trans-respiratory system pressure (Prs)

363
Q

the trans-respiratory system pressure (Prs) measured by

A

measured as the difference between Palv and Pbs:
also,
the sum of the pressures generated by its two components, lung and chest
Prs = Pl + Pw

364
Q

Compliance of the lungs

A

is a parameter that refers to the ease with which each of these structures can be distended`

365
Q

Compliance of the lungs is expressed as

A

expressed as the volume change in the lungs for a unitary change in pressure
- the slope of the pressure-volume curve

366
Q

Compliance of the lungs formula

A

C = dV/dP

367
Q

The standard procedure for measuring the respiratory system compliance in humans

A

to determine the static pressure-volume relationship while lung volume is decreased step by step from TLC

368
Q

The pressure difference between the alveoli (Palv) and the pleural space (Ppl) equals the

A

pressure drop across the lung tissues also known as the pressure required to maintain the lungs at a given inflation volume against their tendency to recoil elastically

369
Q

Compliance of the lungs with certain diseases

A

Compliance of the lungs is also altered in diseases such emphysema and fibrosis

Emphysema: TLC and compliance increases

Fibrosis: TLC and compliance decreases

370
Q

a large part of the recoil forces arises from the? why?

A

properties of the liquid film lining the inside of the lungs

The surface tension in this film generates substantial force because the surface area of the film is very large

371
Q

Compliance of the chest wall

A

defined in terms of a change in thoracic volume dV (the change in volume of the thorax is the same as the change in volume of the lungs) and a change in pressure across the chest wall (w), dPpl

372
Q

What do the elastic properties of the tissues of the thorax (i.e. the chest wall) cause?

A

it to recoil either inward or outward, depending on its volume

373
Q

Compliance of the lungs is positive or negative

A

the pressure reported when measuring the compliance of the lungs were always positive because the lungs always tended to collapse

374
Q

Compliance of the chest wall is positive or negative

A

Pressure reported is sometimes positive sometimes negative
- the chest wall tends to collapse only after reaching a volume after 60% vital capacity whereas it wants to spring out below that value

375
Q

Compliance of respiratory system

A

the compliance of the respiratory system, Crs, is related to the compliances of the lung and chest wall by
Crs = dV/dPrs

376
Q

The pressure drop across the respiratory system

A

Prs, is the sum of the pressure drop across the lung and that across the chest wall

377
Q

Prs at Functional Residual Capacity (FRC)

A

Prs is zero because the system is at rest

378
Q

stable condition is caused by the

A

inward recoil of the lungs (Pl is about +5 cmH2O) which is balanced by the outward recoil of the chest wall (Pcw is about -5 cmH2O)

379
Q

at FRC, what is the resting volume of the lungs and chest?

A

at FRC, the lungs are above their resting volume and the chest is below its resting volume

380
Q

The lungs collapse to its

A

resting position below RV,

381
Q

the chest wall expands towards its

A

resting position

382
Q

Air enters the pleural space because

A

Ppl is less than atmospheric pressure

383
Q

At rest, the lungs are at

A

FRC

384
Q

At rest, the Ppl of the lungs? why?

A

is negative due to the opposite forces acting on the lungs and chest wall

385
Q

During inspiration what does the diaphragm and chest wall do? what does this do to Ppl

A

During inspiration, the diaphragm contracts and the chest wall is pulled open
creates a more negative Ppl that causes expansion of the lungs

386
Q

Flow equation

A

Flow = F = ( Palv - Patm ) / R

387
Q

As the lungs are pulled further away from their resting position (which is below RV), Ppl becomes

A

even more subatmospheric

388
Q

As the volume of the lungs is increased, gas in the lungs is

A

decompressed

389
Q

The pressure in the alveoli (Palv) drops below

A

atmospheric pressure

390
Q

What generates air flow to the lungs?

A

The negative pressure gradient created between the alveoli and atmosphere

391
Q

As inspiration proceeds, the lungs are filling up with air, how is the pressure gradient and air flow change?

A

the pressure gradient and the air flow gradually decreases

392
Q

At the end of inspiration, why does air flow stop?

A

Palv is equal to atmospheric pressure (no pressure gradient)

393
Q

At the onset of expiration, what happens to the diaphragm, and Palv?

A

he diaphragm relaxes, elastic recoil of the respiratory system compresses the gas in the lungs, and Palv increases

394
Q

As lung volume decreases, Ppl

A

slowly returns to its resting level

395
Q

At the end of expiration, air flow, Palv, Ppl, equals.

A

At the end of expiration, i.e. at FRC, air flow=0 ml/s and Palv=0 cmH2O, and Ppl is about -5 cmH20

396
Q

Values of intrapleural pressure range between

A

-5 to -8

397
Q

alveolar pressure ranges between

A

1 to -1

398
Q

The time course of changes in pleural pressure during inspiration and expiration depends on

A

contraction of the diaphragm and airway resistance

399
Q

What is Airway Resistance important for?

A

related to airway caliber and is an important determinant of lung function

400
Q

In certain diseases (such as asthma) airway resistance can become

A

very high making breathing difficult

401
Q

The resistance of the airways to gas flow (Raw)

A

is the ration of the pressure difference and the flow

402
Q

In order to have gas flow through the airways, the pressure at the airway opening compared to the pressure at the alveoli

A

(Pao) must be different from that in the alveoli (Palv)

403
Q

Flow and resistance of a large diameter airway

A

A large diameter airway can carry a large flow for a given pressure difference and so has a smaller resistance than a small diameter airway

404
Q

When a subject inspires to TLC and exhales to RV, during expiration, what happens to flow

A

flow rises very rapidly to a high value and then declines over the rest of expiration.

405
Q

Why is the the descending portion of the flow-volume curve is independent of effort

A

because of the compression of the airways by intrathoracic pressure

406
Q

Before inspiration (A), what is the airway and intrapleural pressure?

A

airway pressure is zero and intrapleural pressure is -5cm H2O.

407
Q 
During inspiration (B), what 
happens to the airway and intrapleural pressure?
A

During inspiration (B), pleural and airway pressures fall.

408
Q

End of inspiration (C), what is the airway and transmural pressure pressure?

A

airway pressure=zero and airway transmural pressure=8 cm H2O.

409
Q

During forced expiration (D), what

happens to the alveolar and intrapleural pressure?

A

During forced expiration (D), intra-pleural and alveolar pressures increase.

410
Q

restrictive diseases

A

pulmonary fibrosis

411
Q

obstructive diseases

A

emphysema

412
Q

the maximum flow rate and maximum volume exhaled in restrictive diseases

A

In restrictive diseases (e.g. pulmonary fibrosis), the maximum flow rate and maximum volume exhaled are reduced (lungs are stiff).

413
Q

the flow rate and appearance in obstructive diseases

A

In obstructive diseases(e.g. emphysema), the flow rate is very low and a scooped out appearance is often seen (lungs are floppy)

414
Q

Inspiration process

A 
Diaphragm and intercostal muscles contract
↓
Thoracic cage expands
↓
Intrapleural pressure becomes more negative (subatmospheric)
  ↓
Transpulmonary pressure increases
↓
 Lungs expands
↓
Alveolar pressure becomes subatmospheric
  ↓
Air flows into alveoli
415
Q

Expiration process

A

Diaphragm and external intercostal muscles stop contracting
↓
Chest wall moves inwards
↓
Intrapleural pressure goes back towards preinspiratory value
↓
Transpulmonary pressure goes back towards preinspiratory value
↓
Lung recoils towards preinspiratory volume
↓
Air in lungs is compressed
↓
Alveolar pressure becomes greater than atmospheric pressure
↓
Air flows out of the lungs

416
Q

Asthma

A

Chronic inflammatory disease of the airways
clinically characterized by airway obstruction, and enhanced airway responsiveness to contractile agonists and/or allergens

417
Q

Emphysema

A

Enlargement of air spaces due to destruction of the alveoli walls The airways tend to collapse because of the loss of radial traction.

The lungs actually self-destruct, attacked by proteolytic enzymes secreted by leukocytes in response to a variety of factors

418
Q

Fibrosis

A

Progressive distortion of the alveolar architecture with inflammation and accumulation of fibrotic tissue

419
Q

When exercise starts, How do tidal volume (VT) and breathing frequency (f) change?

A

increase proportionally

420
Q

peak expiratory flow rate vs peak inspiratory flow rate

A

peak expiratory flow rate increases more than peak inspiratory flow rate

421
Q

During exercise, what happens to do tidal volume (VT) and breathing frequency (f)?

A

VT plateaus; therefore, high ventilatory rates during hard exercise are due to incremental increases in f

422
Q

In both untrained and trained subjects, how does minute ventilation (VE) and metabolic rate (VO2) change?

A

In both untrained and trained subjects, minute ventilation (VE) increases linearly with metabolic rate (VO2) up to about 50% to 65% of VO2 max

423
Q

How does VE change compared to VO2?

A

VE increases at a rate disproportionately greater than the change in VO2

424
Q

effect of endurance training

A

to delay the ventilatory inflection point (Tvent)

425
Q

Affect of Resting values of VE with exercise

A

Resting values of VE can increase 35 folds during exercise (from 5L/min to 190 L/min, in a fit individual)

426
Q

Affect of Resting values of cardiac output (CO) with exercise

A

can increase 5-6 folds during exercise (from 5L/min to 25-30 L/min, in a fit individual)

427
Q

How does VE/Q change with excersise?

A

Because VE can increase more than Q
-The VE/Q
during exercise, there is an increase in VE/Q

428
Q

The alveolar surface area

A

50m2 (1/2 of a single tennis court

429
Q

What % of blood is in the pulmonary system at any one time during maximal exercise

A

4%

430
Q

Does ventilation limit aerobic performance? why?

A

Reason why ventilation is not believed to limit aerobic performance
there is a large capacity for gas exchange

431
Q

During excersise , what is the reponse in the medullary ECF?

A

alkalotic (increase pH)

432
Q

During exercise, there is an alkalotic ( pH), how is the ventilatory response?

A

decreased

433
Q

During excerise, what are peripheral chemorecpetors sensitive to?

A

Peripheral chemoreceptors are mainly sensitive to changes in PO2, but are also stimulated by increased PCO2 and decreased pH

434
Q

PaO2 change during exercise? why?

A

PaO2 remains rather constant during exercise

the increase in ventilation cannot come from the stimulation of the peripheral chemoreceptors by changes in O2

435
Q

PaCO2 change during exercise? why?

A

PaCO2 is often seen to decrease during exercise

the increase in ventilation cannot come from the stimulation of the peripheral chemoreceptors by CO2

436
Q

How does arterial pH change with exercise?

A

during exercise, arterial pH does decrease and PaO2 fluctuates subtly with arterial pulse waves

437
Q

The control for minute ventilation before excercise?

A

neural`

PHGY210 (6 decks)

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