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PT663 > Pulmonary Physiology Part I > Flashcards

Pulmonary Physiology Part I Flashcards

1
Q

What is the main function of the pulmonary system?

A

To exchange gases (oxygen and carbon dioxide) between the environment and the cells to power cellular respiration.

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2
Q

What are the two major gases exchanged by the pulmonary system?

A

Oxygen (O₂) and carbon dioxide (CO₂).

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3
Q

How is oxygen used in the body?

A

Oxygen is transported through the airways, heart, and circulation to the mitochondria, where it powers aerobic metabolism.

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4
Q

What is carbon dioxide’s role in the pulmonary system?

A

CO₂ is a byproduct of aerobic metabolism, transported from tissues through the cardiovascular system to the lungs, and expelled from the body.

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5
Q

Why must the pulmonary system adapt its rate of gas exchange?

A

It adapts to meet the varying metabolic demands of the body, such as during rest or heavy activity.

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6
Q

What is a common way to measure metabolic demand?

A

By measuring the rate of oxygen consumption.

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7
Q

How much can oxygen consumption increase during heavy activity?

A

It can increase up to twentyfold compared to oxygen consumption at rest.

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8
Q

What is “minute ventilation”?

A

The amount of air that is breathed in per minute.

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9
Q

What is the typical range of minute ventilation from rest to heavy activity?

A

From about 5 liters per minute at rest to 100 liters per minute during heavy activity.

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10
Q

What are the two main processes of the pulmonary system discussed in the first lesson?

A

Ventilation (air flow) and defense systems (protection against environmental factors)

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11
Q

Why is the pulmonary system unique in its interaction with the environment?

A

It is the only body system directly exposed to the environment through the airways.

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12
Q

What is ventilation?

A

Ventilation is the bulk flow of air into and out of the lungs, driven by pressure gradients.

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13
Q

What are the key components of the pulmonary system shown in the schematic?

A

Conducting airways, alveoli, chest wall, and intrapleural space (space between the lung and chest wall).

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14
Q

What is the pressure difference necessary for air to flow during ventilation?

A

The pressure difference between the alveoli (P_in) and the atmospheric pressure (P_out).

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15
Q

How does air enter the lungs during inspiration?

A

The diaphragm contracts, increasing thoracic volume and decreasing pressure in the alveoli, which allows air to flow into the lungs.

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16
Q

What happens to thoracic volume and alveolar pressure during inspiration?

A

Thoracic volume increases, causing a decrease in pressure inside the alveoli, leading to air flowing into the lungs.

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17
Q

What role does the diaphragm play in inspiration?

A

The diaphragm’s contraction increases the volume of the thorax, which lowers alveolar pressure and allows air to flow into the lungs.

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18
Q

How does air leave the lungs during exhalation?

A

The diaphragm relaxes, thoracic volume decreases, alveolar pressure increases, and air flows out of the lungs.

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19
Q

What happens to alveolar pressure during exhalation?

A

Alveolar pressure increases as the thoracic volume decreases, causing air to flow out until the pressures inside and outside the alveoli are equal.

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20
Q

What is the relationship between volume and pressure in the thoracic cavity during ventilation?

A

An increase in thoracic volume decreases alveolar pressure (inspiration), and a decrease in thoracic volume increases alveolar pressure (exhalation).

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21
Q

What must be open for air to flow during ventilation?

A

The glottis must be open for air to flow into or out of the lungs.

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22
Q

What happens to the chest wall at its equilibrium point?

A

At equilibrium, with no external pressure, the chest wall’s volume is large, and it returns to this size when not compressed.

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23
Q

How does the lung behave at its equilibrium point?

A

The lung’s volume is small at equilibrium, like a deflated balloon, and it requires external pressure to expand.

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24
Q

How are the lung and chest wall coupled together?

A

The lung and chest wall are coupled through the intrapleural space, which behaves like microscope slides with water between them—tough to separate but able to slide.

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25
Q

What happens when the chest wall and lung are coupled together?

A

The chest wall’s volume decreases (it is pulled inward), and the lung’s volume increases (it is pulled outward).

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26
Q

What pressure is generated by the coupling of the chest wall and lung?

A

A negative intrapleural pressure is created due to the opposing forces of the lung’s tendency to collapse and the chest wall’s tendency to expand.

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27
Q

What is Functional Residual Capacity (FRC)?

A

FRC is the equilibrium point where the expanding force of the chest wall and the collapsing force of the lung are equal, occurring at the end of a normal exhalation.

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28
Q

What is Total Lung Capacity (TLC)?

A

TLC is the maximum volume of air that the lung and chest wall can hold during full inhalation.

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29
Q

What is Residual Volume (RV)?

A

RV is the volume of air remaining in the lungs after a maximal exhalation, which cannot be expelled while the lung and chest wall are coupled.

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30
Q

How does intrapleural pressure change during inhalation?

A

During inhalation, intrapleural pressure becomes more negative, which helps pull the lungs open and decreases alveolar pressure, allowing air to flow in.

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31
Q

What changes occur during exhalation?

A

The diaphragm relaxes, making the intrapleural pressure less negative and increasing alveolar pressure, which pushes air out of the lungs.

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32
Q

How do alveolar pressure changes drive ventilation?

A

During inhalation, alveolar pressure becomes negative, drawing air in. During exhalation, it becomes positive, pushing air out until equilibrium is reached.

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33
Q

What is the role of expiratory muscles in forced exhalation?

A

Expiratory muscles, like the abdominal muscles, help further reduce lung and thoracic volume during forced exhalation.

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34
Q

What is minute ventilation?

A

Minute ventilation is the product of tidal volume (volume of breath during inhalation) and respiratory rate.

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35
Q

How do you calculate minute ventilation with normal values?

A

Multiply a normal tidal volume (450 mL) by a normal respiratory rate (12 breaths/min), resulting in approximately 5,400 mL/min.

36
Q

What is the purpose of ventilation in the lungs?

A

The purpose of ventilation is to bring air into the alveoli, where gas exchange takes place.

37
Q

What is the conducting zone in the lungs?

A

The conducting zone consists of airways where no gas exchange occurs and some air stays, known as anatomical dead space.

38
Q

What is anatomical dead space, and how much air does it typically contain?

A

Anatomical dead space is the part of the airway that doesn’t participate in gas exchange, typically about 150 mL in a healthy person.

39
Q

How do you calculate alveolar ventilation?

A

Alveolar ventilation = (Tidal volume - Dead space volume) × Respiratory rate. For example, (450 mL - 150 mL) × 12 breaths/min = 3.6 L/min.

40
Q

What is the effect of disease on physiological dead space?

A

Diseases can increase physiological dead space by creating regions in the lung that don’t participate in gas exchange.

41
Q

How does gravity affect ventilation distribution in the lungs?

A

Gravity pulls the lungs downward when upright, causing alveoli at the lung base to be smaller and more compliant compared to those at the apex.

42
Q

How does the Slinky analogy relate to the lungs?

A

Like a Slinky, the weight of the lung pulls down, making alveoli at the top more expanded (less compliant) and alveoli at the base smaller and more compliant.

43
Q

What is the compliance of the lungs, and how does it vary?

A

Compliance refers to the lung’s stretchiness. Alveoli at the base are more compliant (easier to expand) than those at the apex due to less initial stretch.

44
Q

How does the difference in alveolar compliance affect ventilation?

A

During inhalation, more air goes to the alveoli at the lung base, which are more compliant and expand more than those at the apex.

45
Q

How does body position affect ventilation distribution?

A

When lying down, ventilation distribution shifts from the base-apex gradient to a difference between the anterior and posterior aspects of the lungs.

46
Q

What is a spirometer used for in lung function testing?

A

A spirometer measures the flow of air to determine the volume of air moved during ventilatory maneuvers.

47
Q

What is tidal volume?

A

Tidal volume is the volume of air breathed in and out during a normal inhalation and exhalation, typically about 450-500 mL per breath.

48
Q

What is the inspiratory reserve volume (IRV)?

A

IRV is the additional volume of air that can be inhaled after a normal inhalation.

49
Q

How is inspiratory capacity (IC) calculated?

A

Inspiratory capacity is the sum of the tidal volume and the inspiratory reserve volume.

50
Q

What is vital capacity (VC)?

A

Vital capacity is the volume of air exhaled from a maximum inhalation to a maximum exhalation.

51
Q

What is expiratory reserve volume (ERV)?

A

ERV is the additional volume of air that can be exhaled after a normal exhalation.

52
Q

What is residual volume (RV)?

A

RV is the volume of air left in the lungs after a maximal exhalation, not measurable with spirometry.

53
Q

What is functional residual capacity (FRC)?

A

FRC is the volume of air remaining in the lungs at the end of a normal exhalation.

54
Q

How is total lung capacity (TLC) calculated?

A

TLC is the sum of the vital capacity (VC) and the residual volume (RV)

55
Q

How are lung volumes and capacities influenced?

A

They are influenced by age, gender, and body size, and can vary with different lung diseases.

56
Q

What is forced vital capacity (FVC)?

A

FVC is the total volume of air exhaled as forcefully and quickly as possible after a maximal inhalation.

57
Q

What does FEV1 measure?

A

FEV1 measures the volume of air exhaled in the first second of the FVC maneuver.

58
Q

Why is the FEV1/FVC ratio important?

A

It indicates what fraction of the total forced vital capacity is exhaled in the first second, often used to diagnose obstructive lung diseases.

59
Q

What is a normal FEV1/FVC ratio?

A

A normal ratio is about 75-80%, meaning that most of the FVC is exhaled in the first second.

60
Q

How does the FEV1/FVC ratio change in obstructive lung diseases?

A

The ratio is generally lower in obstructive lung diseases due to limitations in airflow.

61
Q

What does a flow-volume loop show?

A

It plots volume along the x-axis and airflow along the y-axis, illustrating the relationship between inhalation and exhalation during spirometry.

62
Q

What is a pneumothorax?

A

A condition where air enters the intrapleural space due to a lesion in the lung or chest wall, causing the lung to collapse and the chest wall to expand.

63
Q

How do we treat a pneumothorax?

A

By inserting a chest tube connected to wall suction to remove excess air and allow the lung to re-expand

64
Q

What happens when the muscles of ventilation are weak?

A

It impairs ventilation, making it harder for patients to breathe due to insufficient pressure and volume changes.

65
Q

What is the effect of a high spinal cord injury (C3 or above) on ventilation?

A

It can lead to diaphragm paralysis, making the patient dependent on mechanical ventilation.

66
Q

Define paradoxical breathing pattern

A

A breathing pattern where the abdomen expands but the chest wall collapses during inhalation due to weak intercostal and abdominal muscles.

67
Q

How does airway diameter affect ventilation?

A

arrowing of airways, as seen in asthma, increases resistance to airflow, requiring more muscular effort to maintain ventilation.

68
Q

What is dynamic airway compression?

A

A phenomenon during forced exhalation where increased intrapleural pressure compresses the airways, limiting airflow.

69
Q

What is compliance in the context of lungs?

A

The ability of the lungs to stretch and expand; it can be increased in emphysema or decreased in pulmonary fibrosis.

70
Q

How does emphysema affect lung compliance?

A

It increases lung compliance, making the lung overly stretchy and reducing the elastic recoil needed for exhalation.

71
Q

Why is ventilation harder with pulmonary fibrosis?

A

Pulmonary fibrosis decreases lung compliance, requiring more muscular effort to expand the lungs.

72
Q

What role does surfactant play in the lungs?

A

It reduces surface tension in the alveoli, preventing them from collapsing and aiding in gas exchange.

73
Q

What respiratory issue can premature babies face due to lack of surfactant?

A

They may experience alveolar collapse, leading to respiratory distress.

74
Q

What is the function of the ventilatory pump?

A

To maintain airflow by coupling the lung and chest wall, supporting muscle strength, and managing compliance, surface tension, and airway diameter.

75
Q

How does a decrease in lung compliance affect breathing effort?

A

It requires more effort from the respiratory muscles to expand the lungs, increasing the work of breathing.

76
Q

What is the primary function of the nasal passages in lung protection?

A

The nasal passages filter out larger particles of dust and debris using nose hairs and turbinates, which create turbulent airflow to trap particles.

77
Q

How do turbinates aid in protecting the lungs?

A

Turbinates are shells of bone in the nasal passages that create turbulent airflow, helping to trap larger air particles before they enter deeper airways.

78
Q

What role do macrophages play in lung protection?

A

Macrophages are immune cells in the respiratory zone that engulf particles and bacteria, helping to keep the small airways and alveoli clear.

79
Q

What is the mucociliary escalator?

A

It is a system in the conducting zone where mucus traps particles, and cilia sweep the mucus and trapped particles up towards larger airways for removal.

80
Q

Which factors can impair the function of the cilia in the mucociliary escalator?

A

Smoking, anesthesia, dehydration, and various lung diseases can impair cilia function, leading to retained particles, inflammation, and potential infections.

81
Q

What is the significance of the mucociliary escalator in lung health?

A

It helps clear mucus and trapped particles from the airways, preventing inflammation and infection like pneumonia.

82
Q

What is the primary purpose of a cough in the pulmonary system?

A

A cough helps clear irritants and particles from the airways, protecting the lungs from infection and inflammation.

83
Q

What are the four phases of a cough?

A

1.Inspiration (inhaling about 60% of maximal capacity)
2. Compression (thoracic compression to build pressure), 3. Glottis control (closing to maintain pressure)
4. Expulsion (releasing the glottis to expel air and irritants).

84
Q

Why is assessing a patient’s ability to cough important in clinical settings?

A

It ensures they can effectively clear their airways, which is crucial for preventing respiratory complications, especially in patients with muscular weakness.

85
Q

How can lung protection mechanisms be compromised in clinical populations?

A

Impaired cilia function, weakened cough ability, or decreased mucus clearance can lead to retained particles and increased risk of infections like pneumonia.

86
Q
A

PT663 (22 decks)

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