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HSC1007 A&P > Respiratory Physiology > Flashcards

Respiratory Physiology Flashcards

1
Q

What is the role of the respiratory system in pH regulation?

A
  • Removes CO2, which helps regulate H+ ion concentration (affects acidity).
  • Increased CO2 leads to increased H+ ions (more acidic environment)
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1
Q

What are the functions of the respiratory system? (6 points)

A
  • Provides oxygen to tissues for metabolism
  • Removes carbon dioxide and regulates pH
  • Endocrine functions (activates angiotensin II)
  • Immunological functions (clears irritants, pathogens)
  • Voice production
  • Water loss and heat elimination
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2
Q

How does the respiratory system contribute to immune defense?

A
  • Clears irritants and potential pathogens (bacteria, viruses).
  • Alveolar macrophages engulf foreign particles
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3
Q

List the components of the respiratory system involved in ventilation.

A
  • Nasal passages
  • Pharynx
  • Larynx
  • Trachea
  • Right and left bronchi
  • Bronchioles
  • Alveoli
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4
Q

How is pleural pressure generated?

A
  • The pleural cavity, containing intrapleural fluid, creates a pressure lower than atmospheric pressure.
  • When the diaphragm contracts, it pulls the parietal pleura, expanding the lungs and decreasing pleural pressure.
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5
Q

Why is intrapleural pressure lower than atmospheric pressure?

A

The lungs are always stretched to some degree due to the pressure difference, which keeps them from collapsing.

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6
Q

How does intrapleural pressure help lung expansion?

A

A lower intrapleural pressure compared to intra-alveolar pressure allows the lungs to expand as the thoracic cavity enlarges.

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7
Q

What changes occur in alveolar pressure during inspiration?

A

During inspiration, intra-alveolar pressure < atmospheric pressure, = air to flow into lungs.

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8
Q

What is the relationship between alveolar pressure and atmospheric pressure during expiration?

A

During expiration, intra-alveolar pressure > atmospheric pressure = push air out of the lungs.

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9
Q

How is a negative alveolar pressure created during inspiration?

A
  • Diaphragm contracts
  • This expands the thoracic cavity
  • Which decreases intra-alveolar pressure below atmospheric pressure = draw air in
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10
Q

How is a positive alveolar pressure created during expiration?

A
  • Diaphragm relaxes
  • Decreases the thoracic cavity volume
  • This increases intra-alveolar pressure above atmospheric pressure = push air out.
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11
Q

What are the pressures involved in ventilation?

A
  • Atmospheric pressure: 760 mmHg (at sea level)
  • Intra-alveolar pressure: varies with ventilation
  • Intrapleural pressure: 756 mmHg (lower than atmospheric)
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12
Q

How does air move in and out of the lungs?

A

Air moves according to pressure gradients; air flows from areas of higher pressure to areas of lower pressure.

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13
Q

What happens to the pleural pressure during inspiration?

A

Diaphragm contract = pleural pressure dec. & thoracic cavity expands

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14
Q

What role does the diaphragm play in ventilation?

A

During inspiration = diaphragm contract = inc. thoracic cavity vol.

During expiration = diaphragm relax = reduce thoracic cavity vol.

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15
Q

How do intercostal muscles contribute to ventilation?

A
  • Ext intercostal muscles elevate ribs during inspiration = inc. thoracic cavity vol.
  • int. intercostal muscles help during forced expiration
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16
Q

What is the relationship between the pleural cavity and lung expansion?

A

Pleural cavity contains fluid that allows lung to expand & contract w/o friction as pleural layers slide over e/o

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17
Q

What is the function of alveoli in gas exchange?

A

Alveoli provide a large SA for O2 and CO2 exchange b/w air and blood in capillaries.

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18
Q

How does gas exchange occur in the alveoli?

A

Diffusion
O2 move from alveoli into blood
CO2 move from blood into alveoli

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19
Q

What is the importance of surfactant in the alveoli?

A

Reduce tension = prevent alveoli from collapsing & ensure efficient gas exchange

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20
Q

What is the role of the pleura in lung function?

A

Visceral pleura covers lungs
Parietal pleura lines the thoracic cavity.
The pleural cavity b/w helps reduce friction and help in lung expansion.

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21
Q

How does the pleural pressure prevent lung collapse?

A

Negative pleural pressure (below atm pressure) keeps lung partially inflated = prevent collapse

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22
Q

How does pleural effusion affect lung function?

A

Pleural effusion = fluid in pleural cavity (>50mL)

affect lung expansion & reduce gas exchange efficiency

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23
Q

What is pneumothorax, and how does it affect the lungs?

A

Air enters pleural cavity

Cause lung to collapse bc of loss of -ve pleural pressure

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24
Q

How does airway resistance affect airflow?

A

Inc. resistance (e.g. bronchoconstriction) dec. air flow

Dec. resistance (e.g. bronchodilation) inc. air flow

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25
Q

What is the function of the conducting zone of the respiratory system?

A

Conducting zone = trachea to terminal bronchioles

Tpt air to lungs but does not participate in gas exchange

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26
Q

What is the respiratory zone?

A

Resp. zone = resp bronchioles to alveolar sacs

where gas exchange occurs in lungs

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27
Q

How does the autonomic nervous system regulate airway diameter?

A

Sympathetic stimulation = bronchodilation

parasympathetic stimulation = bronchoconstriction

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28
Q

What happens to alveolar pressure at the end of inspiration and expiration?

A

At the end of inspiration & expiration:
Alveolar pressure = atm pressure

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29
Q

How is alveolar ventilation calculated?

A

Alveolar Ventilation = (Tidal Volume – Dead Space) × Breaths per minute

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30
Q

What are the key components involved in ventilation and gas exchange by diffusion?

A
  • Fresh air reaching the alveoli
  • Effective diffusion of air across the alveolar-capillary barrier
  • Efficient removal of CO2 from the lungs
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31
Q

What factors influence effective oxygenation and CO2 removal in the lungs?

A
  • Ventilation : sufficient air reaching alveoli
  • Perfusion : sufficient blood flow to alveoli
  • Diffusion : efficient gas exchange across alveolar-capillary barrier
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32
Q

How does partial pressure drive the diffusion of O2 and CO2?

A
  • Gas diffuses from areas of high partial pressure to low partial pressure until equalized.

E.g. O2 moves from alveoli (high O2 pressure) to capillary blood (low O2 pressure).

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33
Q

What is partial pressure and how is it calculated for O2 in the air?

A

Partial pressure is the pressure a gas exerts in a mixture, proportional to its percentage.

Partial pressure = % of O2 in air x total air pressure

E.g. Partial pressure = 0.21 (21% of air is O2) x 760 mm Hg (total air pressure at sea level)

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34
Q

How does CO2 diffuse from capillaries to the alveoli?

A

CO2 moves from capillaries (high CO2 partial pressure) to alveoli (low CO2 partial pressure), driven by the pressure gradient.

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35
Q

What influences the rate of gas transfer across the alveolar membrane?

A
  • Partial pressure differences
  • Thickness of the alveolar-capillary barrier
  • Surface area for diffusion
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36
Q

How does exercise affect the rate of gas diffusion across the alveoli?

A

Exercise = more alveoli open = inc. the surface area for diffusion and the rate of gas exchange.

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37
Q

Why does the diffusion of gases stop once partial pressures are equalized?

A

Diffusion only occurs when there is a difference in partial pressure.
Once equalized, no further movement occurs.

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38
Q

What are the main barriers to gas diffusion in the alveoli?

A
  • Alveolar epithelium
  • Capillary endothelium
  • Basement membranes
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39
Q

How does surface area affect gas exchange in the lungs?

A

Larger surface area allows more gas to diffuse across the alveolar membrane

40
Q

What happens if the surface area for diffusion is reduced, such as in emphysema?

A

Emphysema : lung dz that results from damage to walls of alveoli

reduced SA limits the amt of gas exchange, leading to poor oxygenation of blood

41
Q

How does the rate of blood flow through the alveoli affect gas exchange?

A

Blood flow must allow sufficient time for gases to diffuse & equilibrate across the alveolar membrane

42
Q

What happens when blood flow to an alveolus ceases?What happens when blood flow to an alveolus ceases?

A

Gas exchange stops, as blood is no longer available to transport O2 and CO2 (e.g., in pulmonary embolism).

43
Q

How does gravity affect the perfusion of the lungs?

A

Blood flow is greater at the base of the lungs due to gravity, with less perfusion at the apex

44
Q

What are the characteristics of pulmonary circulation?

A

Low pressure, high volume system that always receives 100% of cardiac output

45
Q

How does the low-pressure nature of pulmonary circulation affect gas exchange?

A

Low pressure allows blood to flow more slowly, giving gases time to exchange across the alveolar membrane

46
Q

What is the difference between pulmonary and systemic circulation in terms of pressure?

A

Pulmonary artery pressure: ~25/15 mmHg

Systemic artery pressure: ~120/80 mmHg

47
Q

How do ventilation and perfusion ratios vary between the apex and base of the lungs?

A

Apex: more ventilation, less perfusion

Base: more perfusion, less ventilation

48
Q

What are the local controls to match airflow and blood flow of the lung (large air-flow / small blood flow)?

i.e. apex of lungs

A
  • Areas with more O2 (i.e. apex of lungs) = pulmonary arteriolar smooth muscle relax = dilation of local blood vessels = dec. vascular resistance = inc. bld flow to these areas
  • Areas with low CO2 (i.e. apex of lungs) = inc. contraction of local-airway smooth muscle = constriction of local airways = inc. airway resistance = dec. airflow to these areas
49
Q

What is tidal volume (TV)?

A

Volume of air entering or exiting the lungs during a normal breath (usually ~500 mL)

50
Q

What are the local controls to match airflow and blood flow of the lung (small air-flow / large blood flow)?

i.e. base of the lungs

A
  • Areas with less O2 (i.e. base of lung) = inc contraction of local pulmonary arteriolar smooth muscle = constriction of local bld vessels = inc. vascular resistance = dec. bld flow
  • areas with high CO2 (i.e. base of lungs) = relaxation of local airway smooth muscle = dilation of local airways = dec. airway resistance = inc airflow
51
Q

What is inspiratory reserve volume (IRV)?

A

The additional air that can be inhaled with a maximum effort after a normal tidal inhalation

52
Q

What is expiratory reserve volume (ERV)?

A

The additional air that can be exhaled with a maximum effort after a normal tidal exhalation

53
Q

What is residual volume (RV)?

A

The volume of air remaining in the lungs after a maximal expiration (~1.2 L in men)

54
Q

What factors can change lung volume measurements?

A

Factors like activity level, age, size, and physical fitness can alter tidal volume, IRV, ERV, and RV

55
Q

What is vital capacity (VC)?

A

The total amount of air that can be exhaled after a maximal inhalation (TV + IRV + ERV).

56
Q

How does physical activity affect tidal volume?

A

Tidal volume increases during exercise as the body demands more oxygen and removes more CO2

57
Q

What is minute ventilation, and how is it calculated?

A
  • Minute ventilation = Tidal volume (TV) × Respiratory rate
  • Represents total volume of air moved into and out of the lungs per minute.
58
Q

What is alveolar ventilation?

A
  • Volume of air that reaches the alveoli and participates in gas exchange per minute
  • Alveolar Ventilation = (TV – Dead Space) × Respiratory Rate
59
Q

How is ventilation controlled?

A

Controlled by central and peripheral chemoreceptors –> respond to changes in CO2, O2, and pH levels

60
Q

What are central chemoreceptors, and how do they control breathing?

A
  • Central chemoreceptors located in the medulla
  • Detect changes in CO2 levels in cerebrospinal fluid, inc respiratory rate when CO2 rises.
61
Q

How do peripheral chemoreceptors contribute to the control of respiration?

A
  • Peripheral chemoreceptors located in the carotid and aortic bodies
  • Detect changes in O2 and H+ levels = triggering inc in ventilation when O2 drops or H+ increases.
62
Q

What is the main respiratory regulator?

A

pCO2 is the main regulator of respiration, primarily affecting central chemoreceptors

63
Q

How does pO2 affect respiration? (peripheral chemoreceptors)

A

Peripheral chemoreceptors respond to pO2 levels, but are only triggered when arterial pO2 drops below 60 mmHg.

64
Q

What happens to CO2 in the blood during gas transport

A

CO2 is transported in three forms:
- Dissolved CO2 (~7%)
- Bound to hemoglobin (~23%)
- bicarbonate ions (HCO3-, ~70%)

65
Q

What is the chloride shift, and why is it important in CO2 transport?

A

The chloride shift exchanges bicarbonate ions (HCO3-) with chloride ions (Cl-) to maintain electrical neutrality during CO2 transport

Cl- shift exchanges ions (HCO3-) with Cl- = maintain electrical neutrality during CO2 tpt

66
Q

How does H+ affect breathing?

A

Increased H+ concentration (due to rising CO2) lowers blood pH = stimulates central and peripheral chemoreceptors to inc respiration

67
Q

How does hyperventilation affect blood pH?

A

Hyperventilation lowers CO2 levels, which reduces H+ concentration and inc. blood pH (causing alkalosis).

68
Q

How does alveolar area affect gas diffusion?

A
  • Larger alveolar area increases surface area for gas exchange = improve diffusion
  • Reduced alveolar area (e.g., in emphysema) dec diffusion efficiency
69
Q

How does membrane thickness affect gas diffusion?

A
  • Thicker alveolar-capillary membranes (e.g., fibrosis, edema) slow down diffusion
  • Normal membrane thickness (~0.5 µm) allows rapid diffusion of O2 and CO2
70
Q

What happens to gas diffusion at high altitudes?

A

Reduced atmospheric pressure = dec the partial pressure of O2 = less O2 diffusion across the alveolar membrane

70
Q

How does abnormal thickening of the alveolar-capillary barrier affect diffusion?

A

Conditions like pulmonary fibrosis or edema increase barrier thickness = slow gas diffusion.

71
Q

What is lung compliance?

A
  • Lung compliance refers to how easily the lungs and chest wall expand in response to pressure changes
  • Compliance = Change in lung volume / Change in pressure (ΔV/ΔP)
72
Q

How does elastic recoil affect lung compliance?

A
  • Greater lung recoil (e.g., in fibrosis) dec. compliance = make lungs stiffer and harder to inflate
  • Lower lung recoil (e.g., in emphysema) inc. compliance = lungs easy to inflate but harder to empty.
73
Q

What role does surface tension play in lung compliance?

A

Surface tension in the alveoli creates inward pressure = reduce compliance = harder for the lungs to expand

74
Q

What is the function of surfactant in the lungs?

A

Surfactant dec. surface tension in the alveoli = prevent collapse & improve lung compliance

75
Q

How does the absence of surfactant affect lung function?

A

Lack of surfactant (e.g., in premature babies) causes alveolar collapse = leads to respiratory distress syndrome

75
Q

How does surfactant contribute to alveolar stability at low lung volumes?

A

Surfactant lowers surface tension more in smaller alveoli = equalise pressure (with larger alveoli) = preventing collapse

76
Q

What is alveolar interdependence?

A

Refers to the mechanical support alveoli provide each other to prevent collapse = maintaining alveolar stability

76
Q

What factors affect airway resistance?

A
  • Airway diameter (narrower airways increase resistance).
  • Lung volume (lower volume increases resistance).
  • Mucus accumulation.
  • Bronchoconstriction (e.g., in asthma)
76
Q

How does bronchoconstriction affect airway resistance?

A

Constriction of bronchioles (e.g., due to irritants or asthma) narrows the airways = inc. resistance = make breathing difficult

76
Q

What is spirometry, and what does it measure?

A

Spirometry is a test that measures lung volumes and airflow rates. It is used to assess conditions like asthma and COPD

77
Q

How do sympathetic and parasympathetic nerves affect airway resistance?

A

Sympathetic stimulation: bronchodilation = reducing resistance

Parasympathetic stimulation: bronchoconstriction = inc resistance

78
Q

What does FEV1/FVC represent in spirometry?

A

FEV1: forced expiratory volume in 1 second after a full inspiration

FVC: forced vital capacity, or the total air expired forcefully

FEV1/FVC < 0.8 may indicate airway narrowing (e.g. asthma)

79
Q

How is oxygen transported in the blood?

A
  • 98% of oxygen is tpted bound to hemoglobin (Hb).
  • 1-2% dissolved in plasma
80
Q

How is carbon dioxide transported in the blood?

A
  • 70% as bicarbonate (HCO3-)
  • 23% bound to proteins, including hemoglobin (as carbamino compounds)
  • 7% dissolved in plasma
81
Q

What factors affect hemoglobin’s affinity for oxygen?

A
  • pH (Bohr effect)
  • temperature
  • levels of 2,3-DPG

Lower pH, higher temperature, and higher 2,3-DPG levels dec. affinity = promote O2 release to tissues

82
Q

What is the oxygen-hemoglobin dissociation curve?

A
  • The curve shows the rs b/w partial pressure of O2 (PO2) & hemoglobin saturation
  • Has a sigmoidal shape, with a plateau in the lungs and a steep slope in tissues
83
Q

How does the oxygen-hemoglobin curve shift during exercise?

A
  • During exercise, the curve shifts to the right - - indicates reduced hemoglobin affinity for O2 = facilitates O2 release to tissues
84
Q

What is the Bohr effect?

A

Describes how lower pH (higher H+ concentration) dec. hemoglobin’s affinity for O2 = enhance O2 release to tissues

85
Q

How does temperature affect the oxygen-hemoglobin dissociation curve?

A

inc. temperature dec. hemoglobin’s affinity for O2 = shift the curve to the right and promoting O2 release

86
Q

How does 2,3-DPG affect oxygen transport?

A

2,3-DPG dec. hemoglobin’s affinity for O2 = facilitates O2 release to tissues
esp during hypoxia/exercise

87
Q

How does exercise affect O2 and CO2 balance in the body?

A

Inc. oxygen dd and CO2 production = body inc. ventilation & blood flow to match metabolic needs

88
Q

What happens to CO2 levels during exercise?

A

CO2 levels inc = ventilation inc to remove excess CO2 & maintain acid-base balance

89
Q

How does the body maintain acid-base balance during exercise?

A

Inc. ventilation removes CO2 = reducing H+ conc. & helping to maintain blood pH

90
Q

How does oxygen delivery to tissues change during exercise?

A
  • Oxygen delivery inc. due to inc. cardiac output
  • more efficient hemoglobin oxygen release (due to lower affinity) + enhanced tissue perfusion
91
Q

What is the chloride shift, and how does it relate to CO2 transport?

A

Cl- shift exchanges bicarbonate (HCO3-) with chloride (Cl-) in RBCs = maintain electrical neutrality during CO2 tpt

92
Q

What is the normal PO2 and PCO2 in alveolar air?

A

PO2: 102 mm Hg
PCO2: 40 mm Hg

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