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Physiology > Respiratory Study Questions > Flashcards

Respiratory Study Questions Flashcards

1
Q

Describe the cell types found in the alveolus and name their function

A
  • type 1 epithelial: majority of alveolar surface area
  • type 2 epithelial: produces surfactant and repair epithelial damage
  • brush cells: not known
  • macrophages: immune defense
  • PMNs (polymorphonuclear neutrophils): immune defense
  • mast cells: immune defense
  • clara cells: secretory functions
  • endothelial cells: inner lining of alveolus
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2
Q

What is the symbol for partial pressure of oxygen in the mixed venous blood?

A

PvO2

- line above the v indicates mixed venous (mean venous)

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3
Q

What is the symbol for carbon dioxide production?

A

VCO2

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4
Q

What is the symbol for expired minute ventilation?

A

VE

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5
Q

What is the symbol for tidal volume?

A

VT

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6
Q

Name 3 functions of the nasal cavity

A

Warms, filters, humidifies inspired air

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7
Q

What is the contribution to resistance during normal breathing for the nasal cavity? Trachea?

A
  • nasal cavity: 50%
  • trachea: 20%
  • bronchi: 20%
  • bronchioles: 10%
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8
Q

Describe the histologic structure of the trachea

A

Mucosa is classified as pseudostratified ciliated columnar epithelium

  • apocrine, or goblet cells are also present to secrete mucous
  • basal cells on innermost lumen
  • ciliated cells to participate in mucociliary elevator to move out foreign debris
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9
Q

Compare and contrast the structure of the trachea to the bronchioles

A
  • carilage in trachea, but not in the bronchioles
  • no gas exchange in either
  • clara cells in bronchioles, not in trachea
  • epithelium flattens down toward the alveolus, cuboidal in bronchioles and psuedo columnar in trachea
  • smooth muscle in bronchioles
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10
Q

What is the major muscle responsible for quiet inspiration? Accessory muscles?

A

Diaphragm - triggered by action potential delivered by phrenic nerve
- accessory muscles - sternomastoids, scalene

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11
Q

What are the 2 muscles of inspiration?

A

Cricoarytenoideus dorsalis and dilator nasoapicalis

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12
Q

Be able to calculate dead space and alveolar gas tension, and know the different factors that are important to each

A

Dead space: alveoli that are ventilating, but not perfused so carbon dioxide is not exchanged

  • VD/VT = (PaCO2-PECO2)/PaCO2
  • PaCO2 = partial pressure of alveoli carbon dioxide
  • PECO2 = partial pressure of expired carbon dioxide
  • VD = volume of dead space
  • VT = tidal volume
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13
Q

Name 2 tests that can be used to assess pulmonary function

A 
Pulmonary function:
- blood gas analysis
- capnography
- pulse oximetry
Respiratory system:
- radiography
- bronchoscopy
- cytology/biopsy
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14
Q

VT

A

Tidal volume

  • volume of air that gets in and out of lungs in 1 normal ventilation
  • body mass times 10/15 for average
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15
Q

FRC

A 
Functional reserve (residual) capacity
- 2 volumes responsible for gas exchange
- ventilation mechanics need to match flow
- normal decreases occur during pregnancy
FRC = ERV + RV
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16
Q

IC

A

Inspiratory capacity
- one normal conscious inspiration (requires effort)
IC = IRV + VT

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17
Q

IRV

A

Inspiratory reserve volume

- inspiratory volume if you take out tidal volume

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18
Q

TLC

A

Total lung capacity
- max volume of air that lungs are able to take
TLC = IRV + VT + ERV + RV

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19
Q

VC

A

Vital capacity
- can change with pathological conditions or medically
VC = IRV + VT + ERV + RV

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20
Q

To have at least 1 capacity, you need at least ________

A

2 different volumes

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21
Q

What is expired minute ventilation? How can it be calculated?

A

Represents a volume (liter or ml) of lung gas per minute

VE = VT x f (frequency of breaths per min)

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22
Q

Pulmonary compliance

A

Change in volume per unit pressure (how easily the lungs will expand)
C = V/P

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23
Q

What is the most important determinant of compliance behavior of the lung?

A 
Surface tension (2/3)
- each alveolus is an air-water interface
- surface tension promotes deflation (responsible for 2/3 of the compliance behavior) 
Elastic recoil (1/3)
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24
Q

Alveolar gas tension

A
  • PIO2 = (PB-PH2O) x FIO2

- PaCO2 = 1:1 ratio with PACO2 at the alveoli level (can be used interchangeably)

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25
Q

What is the expected partial pressure of O2 in systemic arterial blood? In blood from the pulmonary artery? The alveolus?

A
  • PO2 in systemic arterial blood = 85-100 mmHg
  • PO2 in pulmonary artery blood = 40 mmHg
  • PO2 in alveolus = 104 mmHg
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26
Q

What is the PO2 of moist inspired gas of a dog standing on the summit of Mount Everest (PB = 247 mmHg)?

A

PO2 = FIO2 x (PB-PH2O)

- PO2 = 0.21 x (247-47) = 42

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27
Q

What is hysteresis?

A

Term used to describe that there is a difference between the inflation and deflation curves of the lung
- takes slightly more pressure to inflate the lungs then to deflate (which is passive in most species)

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28
Q

What are the major components of surfactant?

A
  • DPPC: dipalmitoyl phosphatidylcholine (major component with a hydrophobic and hydrophilic component)
  • Ca++
  • apoproteins SP-A, B, C, and D
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29
Q

What are the functions of surfactant?

A
  • decreases work of breathing
  • increases compliance
  • stabilizes alveolar size
  • has a drying effect on the alveoli
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30
Q

Describe what happens to the lung and chest wall when a pneumothorax is induced

A
  • When atmospheric air is introduced into the intrapleural space, eliminating the negative pressure
  • introduction of air into the intrapleural space can be via damage to the chest wall, the lungs, the mediastinum, etc
  • net result = loss of tethering between the lungs and chest wall, allowing the lungs to collapse and the chest wall to expand without a net movement of air
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31
Q

What is the major difference between static and dynamic compliance of the respiratory system?

A

Dynamic compliance has additional factors of - airway resistance, tissue resistance, and inertia
* airway resistance is most important*

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32
Q

What components are common between static and dynamic compliance?

A
  • elastic properties of chest wall
  • elastic properties of lung
  • surface tension
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33
Q

Static compliance

A

Compliance of each component (lung vs chest wall)

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34
Q

What is dynamic compliance and how does it limit expiratory flow?

A

Compliance of the components working together, which will define the work of breathing
- limits expiratory flow via tissue or airway resistance

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35
Q

What factors determine airway resistance?

A

Generation determines resistance

  • -> earlier generations in the flow of air (nasal cavity, large and medium bronchi) offer greater resistance than those further into the lung
  • -> resistance decreases when cross-sectional area increases!
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36
Q

Where does turbulent flow occur in the normal tracheobronchial tree?

A

Turbulent flow occurs in the upper respiratory airways

- due to high resistance and large volume of trachea

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37
Q

What type of flow occurs in the majority of the lung?

A

Transitional flow

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38
Q

What does interdependence of structure mean (i.e., mechanical tethering)?

A

Inflation of 1 alveoli tends to augment/increase the inflation of adjacent alveoli

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39
Q

Using Bohr’s equation determine physiologic dead space in a dog with PaCO2 = 40 mmHg and PECO2 = 30 mmHg

A

VD/VT = PaCO2-PECO2/PaCO2
= 40-30/40
= .25

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40
Q

With regard to the pulmonary circulation, describe what is meant by “shunting” of blood

A

A small percentage of pulmonary blood is not oxygenated correctly

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41
Q

List 5 differences between the pulmonary and systemic circulation

A 
Pulmonary
- uniform, not much change
- low pressure
- thin-walled arteries
- less autonomic control influence
Systemic
- changes depending on organ system or body condition
- high pressure
- high vascular resistance
- thick-walled arteries
- tremendous autonomic control influence
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42
Q

What is the blood volume of the pulmonary circulation? What factors influence pulmonary blood volume?

A 
Pulmonary blood volume = 10%
Factors:
- changes in posture
- changes in systemic vasomotor tone (sleeping, exercising)
- left heart failure
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43
Q

Describe the effect of gravity on pulmonary blood flow (zone 1)

A

Dorsal - blood perfusion is least

  • PA>Pa>Pv
  • alveolar ventilation is high, perfusion is low
  • high V/Q
  • dead space ventilation
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44
Q

Describe the effect of gravity on pulmonary blood flow (zone 2)

A

Middle - blood perfusion is uniform

  • Pa>PA>Pv
  • alveolar ventilation and pulmonary perfusion matched well
  • good V/Q relationship
45
Q

Describe the effect of gravity on pulmonary blood flow (zone 3)

A

Ventral - blood perfusion is most

  • Pa>Pv>PA
  • alveolar ventilation is low but perfusion is high
  • low V/Q
  • alveoli become atelectic
  • zone of pulmonary shunting
46
Q

Define hypoxic pulmonary vasoconstriction

A

Effect of altitude on pulmonary vascular resistance (PVR) and pulmonary arterial pressure (PAP)

  • altitude increases = PO2 decreases, PVR increases
  • pulmonary vascular response to areas of hypoxia in the lungs
47
Q

Describe the effect on lung volume on pulmonary vascular resistance

A

As lung volume increases, pulmonary vascular resistance will increase
- alveoli squeeze the thin-walled pulmonary vessels that line the alveoli

48
Q

Write the Starling equation for fluid flux, define its variables, describe how changes in each will affect fluid flux from pulmonary capillaries

A

Flux = K[(Pc-Pi)-o(3.14c-3.14i)

  • K = filtration coefficient/permeability of endothelial barrier
  • o = reflection coefficient/how much water is returned
  • Pc = capillary hydrostatic pressure (pushes fluid out)
  • Pi = interstitial hydrostatic pressure (pushes fluid in)
  • 3.14c = capillary oncotic pressure (fluid in capillary)
  • 3.14i = interstitial oncotic pressure (fluid out capillary)
  • edema results from increases in this equation*
49
Q

Define pleural effusion and describe the factors that can contribute to it

A

Fluid between visceral and parietal pleural linings of the lungs
- fluid accumulation in the pulmonary interstitium, can result from failure of the lymphatic system properly drain the area

50
Q

Diseases that can result in pulmonary edema

A
  • left sided heart failure
  • capillary endothelial damage
  • severe exercise (race horses)
  • pulmonary hypertension (abnormally high blood pressure in the arteries of the lungs)
51
Q

Why does pulmonary vascular resistance fall during exercise?

A

Increases blood flow through lungs during exercise –> decreases pulmonary vascular resistance

52
Q

What is Dalton’s Law?

A

The sum of all partial pressure of individual gases will equal the atmospheric pressure

53
Q

What is Henry’s Law?

A

The pressure of gas in a liquid is determined by the concentration of the gas and its solubility
P = concentration/solubility

54
Q

Solubility coefficients

A

CO2 > O2 > CO > N2 > He

55
Q

What is the FIO2 on top of Mount Everest?

A

21%

56
Q

List the factors that determine diffusion of oxygen across the alveolar barrier?

A 
Thickness of alveolar membrane
- alveolar edema
- interstitial edema
- pulmonary fibrosis
Altered surface area
- emphysema
- exercise
57
Q

Which step in the diffusion process is rate limiting?

A

Thickness of the alveolar membrane –> affects diffusion time across the membrane

Quiz answer:

  • partial pressure difference
  • diffusion distance thru tissue water
  • cross sectional area
  • molecular weight and gas solubility
58
Q

Describe the oxygen tension gradient between the ambient air and the cell

A

Oxygen tension decreases from dry air to the cell

  • dry air: 160 mmHg
  • intracellular: 5-40 mmHg
59
Q

What is normal arterial oxygen tension?

A

85-100 mmHg

60
Q

What is the normal alveolar tension?

A

104 mmHg

61
Q

Why is the arterial oxygen tension less than the alveolar oxygen tension?

A

Shunts allow blood to reach the arterial system without passing thru ventilated areas of the lungs
- when a small amount of shunted blood is added to arterial blood, O2 concentration is depressed = large fall in PaO2 because O22 dissociation curve is so flat in the upper range

62
Q 
What are the normal values for the following: 
PaO2
PvO2
PaCO2
PvCO2
A
  • PaO2: 85-100 mmHg
  • PvO2: 40
  • PaCO2: 40
  • PvCO2: 40-45
63
Q

Write the alveolar gas equation

A

PAO2 = PIO2 - PaCO2/R
R = 0.8
PIO2 determined by FIO2

64
Q

What is the D(A-a)O2?

A

Alveolar-arterial oxygen difference

  • represents the amount of oxygen removed by metabolically active tissues throughout the body
  • is normally 5-20 mmHg when FIO2 is 0.21
65
Q

List the 4 causes of hypoxemia

A
  • decreased alveolar volume over time (lung volume)
  • decreased oxygen fraction (FIO2)
  • diffusion impairment
  • ventilation/perfusion inequalities
66
Q

Define intrapulmonary shunt

A

Pulmonary shunt = venous admixture (blood that doesn’t pass thru functional pulmonary capillaries)

  • is perfused, but not ventilated (does not undergo gas exchange)
  • low V/Q
67
Q

Describe the relationship between O2 content and O2 partial pressure for whole blood

A

Oxygen content is a function of both hemoglobin saturation with O2 and the partial pressure of dissolved oxygen.
- partial pressure only contributes a small amount to total oxygen content, but its important because oxygen must first dissolve in the blood in order to become saturated

68
Q

Name the factors that will cause a shift in the oxygen-hemoglobin dissociation curve

A
  • increased H ions
  • increased CO2
  • increased temperature
  • increased BPG
69
Q

What is the Bohr effect?

A

Shift in the oxygen-hemoglobin dissociation curve as a result of changes in PCO2

  • high PCO2 –> high H+ –> decreased O2 affinity (enhanced O2 release to tissue)
  • low PCO2 –> low H+ –> increased O2 affinity (enchanced O2 loading in lungs)
70
Q

What is nitric oxide? How does it affect carriage of oxygen?

A

Produced by vascular endothelial cells

  • has a high affinity for ferrous binding sites on hemoglobin
  • is transported by hemoglobin to tissues, where it is released and reduces vascular resistance, while enhancing O2 transport (vasodilator)
71
Q

How is CO2 carried in the blood?

A

Carried as a bicarbonate

  • goes into RBC and is converted to bicarb via carbonic anhydrase
  • bicarb exits RBC and is carried in plasma
72
Q

List 4 ways to assess oxygenation in a patient

A
  • mucous membrane color
  • arterial blood gas analysis
  • pulse oximetry
  • co-oximetry
73
Q

A normal dog is given propofol to induce anesthesia. It halves is alveolar ventilation, but does not affect his CO2 production. What would you predict is PaCO2 to be? Assume R=0.8, what will his PAO2 be?

A

PACO2 = PIO2 - (PaCO2/R)
= (760-47) x 0.21
= 150

PaCO is normally 40, but ventilation is cut in half while production remains the same, so it doubles to 80
PACO2 = 150 - (80/0.8)
= 150-100
= 50

74
Q

A dog is anesthetized and has a pulmonary and systemic arterial catheter placed. The O2 content of the dog’s pulmonary arterial and systemic arterial blood are 14 and 16 mL. Assume that blood leaving a function alveolus has a content of 20 mL, what is this animal’s shunt fraction?

A

QS/QT = 20-16/20-14 = 4/6 = 0.67

75
Q

Will oxygen supplementation improve arterial oxygenation in a patient with a right-to-left shunt?

A

No

  • O2 supplementation may improve the oxygenation of the blood slightly, it will not have a significant impact
  • to improve arterial oxygenation, blood will need to become perfused by the pulmonary system
76
Q

Translate FIO2

A

Fraction of inspired oxygen

77
Q

Your patient is on 1 L/min of 100% oxygen. What is the FIO2? if you increase the flowrate to 2L/min, what is the FIO2?

A

1 L/min of 100% O2 = 1

2 L/min = 1

78
Q

What role does myoglobin play in oxygen transport?

A

Myoglobin acts as a facilitator for DO2 from blood to mitochondria

79
Q

What is the function of the dorsal respiratory group?

A

Medullary center that controls ventilator muscles and ventilation

  • responsible for ramping effect during inspiration
  • sets the rate and depth of ventilation
  • automatically begins ventilation regardless of input
  • receives input from chemo/baroreceptors via vagus and glossopharyngeal nerves
  • airway stretch receptors send info to DRG via vagus nerve, efferent info via phrenic nerve
80
Q

What is the function of the ventral respiratory group?

A

Not active during normal breathing

  • activated during exercise, fear, disease
  • affects DRG to cause an increased ramping effect and directly affects the ventilator muscles to increase inspiratory volume
  • causes an active expiration phase
  • receives info thru vagus and glossopharyngeal nerves
  • sends info thru phrenic nerve
81
Q

How do the central chemoreceptors sense changes in O2?

A

Central chemoreceptors don’t sense changes in PO2, but they do sense PCO2 by sensing changes in the pH

  • CO2 can cross the BBB where it diffuses into bicarb and H ions via carbonic anhydrase
  • CO2 is responsible for changes in ventilation
82
Q

Where are the peripheral chemoreceptors located

A

Carotid and aortic bodies

- can sense both PCO2 and PO2, but their primary influence is PO2

83
Q

What is the primary stimulus for ventilation in a healthy patient?

A

PCO2

- carbonic acid equation is extremely important

84
Q

At what PO2 does hypoxic drive become significant?

A

When PO2 drops below 60-70 mmHg

85
Q

Where does gas exchange occur in the fetus?

A

Placenta

86
Q

What is surfactant and why is it important?

A

Reduces work of breathing, dries alveoli, and reduces surface tension
- produced just prior to birth and is correlated with a surge in fetal corticosteroid production

87
Q

Is systemic blood pressure lower or higher in the fetus than in the dam?

A

Lower

88
Q

What is the PO2 of blood reaching the fetal brain?

A

17 mmHg

89
Q

What changes occur during birth that alter the function of the respiratory system?

A
  • placenta breaks away = decreased circulatory pressure
  • fetus passes thru pelvis and expels fluid in lungs
  • fetus meets cold environment and inhales O2 rich gas
  • lungs fill with O2 = increases PO2 in blood, decreases PVR
  • increased PO2 = ductus arteriosis constriction
  • pressure shift from high RV and low LV to low RV and high LV
  • foramen ovale closes
  • circulation changes from left to right
90
Q

What is unique about fetal hemoglobin?

A

Higher O2 affinity

91
Q

What are the differences between avian and mammalian respiratory systems?

A

Avian is completely passive
- air fills posterior sac –> transferred thru lungs and into anterior sac –> expelled
Mammalian is active for inhalation and passive for exhalation

92
Q

Describe the composition of airway fluid

A

Mucociliary apparatus - serous fluid within the cilia and a mucus layer on top that moves upward and out of the airways to be swallowed

93
Q

Describe the different mechanisms that are utilized in the removal of inhaled particles

A
  • filtration
  • mucociliary elevator
  • smallest particles can be phagocytized by pulmonary macrophages
94
Q

List the filtration and anticoagulant functions of the pulmonary circulation

A
  • blood clots, fat, and air that come thru can either be phagocytized or exhaled
  • anticoagulants are activated or deactivated in the lungs
95
Q

What is angiotensin I and how is it affected by the lung?

A

Involved in kidney function thru the renin-angiotensin system
- converted to angiotensin II in the lungs by way of angiotensin converting enzyme

96
Q

Describe the role of the lung in temperature regulation

A
  • heat: dead space ventilation is increased in order to utilize evaporative cooling
  • cold: dead space ventilation is decreased to hold onto heat
97
Q

What is the inspired PO2 at an atmospheric pressure of 155 mmHg?

A

0.21 x 155 = 32.55 mmHg

98
Q

What would you predict would happen should an animal or human become exposed to this atmospheric pressure?

A

They would need oxygen since there would be limited amounts at this altitude

99
Q

Why do stored RBCs not function as well as fresh RBCs? What is missing?

A

Stored RBCs scavenge and hold onto nitric oxide

100
Q

Is breathing 100% O2 the same as hyperbaric oxygenation?

A

Yes

101
Q

How does hyperbaric O2 improve tissue oxygenation?

A

Combines high pressure and pure oxygen increasing the concentration of oxygen in bloodstream, which permeates deep into body tissues to help promote healing

102
Q

Are there any side effects or dangers associated with hyperbaric oxygen?

A

Some patients may develop changes in eyesight - temporary myopia caused by increased blood oxygen levels

103
Q

What happens to mental function when PaCO2 is >80 mmHg?

A

Severe anxiety due to hypoxia

104
Q

How do anesthetic drugs affect the response to CO2?

A

Sensitize the response to CO2

- pulmonary system becomes unresponsive

105
Q

How do anesthetic drugs affect the response to O2?

A

Dull the response or eliminate it completely, even when PO2 is less than 60-70 mmHg

106
Q

List 4 things that can lead to hypoxemia during anesthesia

A
  • decreased minute ventilation
  • increased shunt fraction
  • increased dead space ventilation
  • decreased FRC
107
Q

Describe how positive pressure ventilation affects venous return

A

Forcing air into the alveoli in order to inhale
- decreases venous return because heart rate and systemic vascular resistance are increased, redistribution of systemic blood flow

108
Q

What happens to pleural pressure during positive-pressure ventilation? Venous return?

A

Positive intrapleural pressure: air is being forced in, no longer being drawn in as with the negative pressure under normal physiologic conditions

109
Q

How do whales stay active underwater for prolonged periods of time?

A

They have tons of myoglobin

- 30 x greater than terrestrial mammals

Physiology (33 decks)

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