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APEX > Respiratory Physiology > Flashcards

Respiratory Physiology Flashcards

1
Q

What are the two critical functions of ventilation?

A
  1. 02 is delivered to hemoglobin to support aerobic metabolism.
  2. C02 is eliminated from the blood
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2
Q

Contraction of the inspiratory muscles reduces thoracic pressure and increases thoracic volume, this is an example of what law?

A

Boyle’s law

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3
Q

The diaphragm lowers and thoracic pressure is reduced during which part of the respiratory cycle?

A

Inspiration

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4
Q

Which part of the respiratory cycle is passive?

A

Exhalation

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5
Q

The Mnemonic “I let the air out of my TIREs” is used to name the muscles involved in exhalation, name them.

A

Transverse abdominis
Internal oblique
Rectus abdominis
External oblique

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6
Q

A vital capacity of at least what amount is required for an effective cough?

A

15ml/kg

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7
Q

What two situations can cause exhalation to become an active process?

A

+ when minute ventilation is increased

+ with lung diseases such as COPD

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8
Q

Which part of the respiratory cycle is driven by the recoil of the chest wall?

A

Exhalation

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9
Q

True or False

Air will always follow the pressure gradient?

A

True

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10
Q

The airway can be divided into three zones, name them.

A

conducting zone
respiratory zone
transitional zone

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11
Q

Which zone of the airway does not participate in gas exchange?

A

conducting zone

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12
Q

Which zone is where gas exchange takes place?

A

Respiratory zone

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13
Q

Which zone is anatomic dead space?

A

conducting zone

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14
Q

which zone begins at the nares and mouth and ends with the terminal bronchioles?

A

conducting zone

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15
Q

Which zone serves the dual function of air conduit and gas exchange?

A

Transitional zone

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16
Q

The respiratory bronchioles and alveolar ducts are considered part of which zone?

A

Transitional zone

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17
Q

Which zone begins at the respiratory bronchioles and also includes the alveolar ducts and alveolar sacs?

A

Respiratory zone

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18
Q

What is the last structure perfused by the bronchial circulation?

A

terminal bronchioles

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19
Q

True or False

Gas exchange can not occur across a flat epithelium?

A

False,

gas exchange can ONLY occur across the flat epithelium

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20
Q

In what zone is cilia most prevalent?

A

conducting zone

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21
Q

In what zone does the bulk of gas movement occur?

A

conducting zone

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22
Q

In the airway, most cartilage is present where?

A

Trachea (patchy in the bronchi)

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23
Q

Can you name the structures of the airway from Trachea to alveolar sacs?

A 
Trachea
Bronchi
Bronchioles
respiratory bronchioles
alveolar ducts
alveolar sacs
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24
Q

alveolar ducts and alveolar sacs belong to which zone?

A

Respiratory zone

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25
Q

Respiratory bronchioles belong to which zone?

A

Transitional zone

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26
Q

what is alveolar pressure?

A

pressure inside the airway

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27
Q

what is intrapleural pressure?

A

pressure outside the airway

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28
Q

What is Transpulmonary pulmonary pressure?

A

The difference between the pressure inside the airway and the pressure outside the airway.

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29
Q

What happens if TPP is a positive value vs a negative value?

A

positive value then the airway stays open

negative value then the airway collapses

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30
Q

intrapleural pressure is always positive or negative during tidal breathing?

A

negative (this keeps the lungs inflated)

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31
Q

Transpulmonary pressure is always positive or negative during tidal breathing?

A

always positive (keeps airway open)

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32
Q

alveolar pressure becomes slightly negative during which phase of the respiratory cycle and slightly positive during which phase of the respiratory cycle?

A

slightly negative during inspiration and slightly positive during expiration

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33
Q

At what two states of tidal breathing is there NO airflow?

A

no airflow during FRC or end-inspiration

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34
Q

What is the only breathing situation in which intrapleural pressure becomes positive?

A

during forced expiration

would be positive during pneumothorax but this is not a normal state

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35
Q

What is your TPP at FRC?

A

+5

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36
Q

What is your TPP during normal inspiration?

A

+7

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37
Q

What is your TPP at end-inspiration?

A

+8

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38
Q

What is your TPP during quite expiration?

A

+6

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39
Q

What is your TPP during forced expiration?

A

-1

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40
Q

Define tidal volume?

A

The amount of gas that is inhaled and exhaled during the breath

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41
Q

Normal dead space is?

A

2ml/kg

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42
Q

When a patient exhales which zone of gas is removed first?

A

conducting zone (dead space) gas is removed first.

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43
Q

Is gas from the respiratory zone removed first or last during exhalation?

A

removed last

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44
Q

Any condition that increases what makes it more difficult to eliminate expiratory gases from the lungs?

A

any condition that increases tidal volume

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45
Q

increased tidal volume widens what gradient and causes CO2 retention.

A

increased tidal volume widens the PaC02-EtC02 gradient and causes CO2 retention

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46
Q

What is minute ventilation?

A

the amount of air in a single breath (Vt) multiplied by the number of breaths per minute.

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47
Q

What is ventilation rate?

A

the volume of air moved into and out of the lungs in a given period of time.

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48
Q

what is the formula for minute ventilation?

A

Minute ventilation = Tidal volume x Respiratory rate

or

VE = Vt x RR

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49
Q

What is the minute ventilation of a patient with a Vt of 500ml who has a RR of 10?

A

500ml x 10 RR = 5,000mL/min

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50
Q

What is Alveolar Ventilation?

A

VA only measures the fraction of VE that is available for gas exchange. It removes dead space gas from the minute ventilation equation.

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51
Q

What is the formula for alveolar ventilation?

A

alveolar ventilation = (tidal volume - dead space) x RR

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52
Q

You can also relate Alveolar ventilation to PaC02, what is the formula when you do this?

A

alveolar ventilation = C02 production / Pac02

VA is directly proportional to carbon dioxide production.

VA is inversely proportional to PaC02

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53
Q

What is the primary determinant of carbon dioxide elimination?

A

alveolar ventilation

this is bc VA takes out dead space which does not contribute to gas exchange

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54
Q

What is the most common cause of Vd/Vt under general anesthesia?

A

reduction in cardiac output

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55
Q

If the Etc02 in the general anesthesia patient acutely decreases you should first rule out what?

A

hypotension

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56
Q

How does atropine increase Vd (dead space)?

A

bronchodilator action increases the volume of the conducting airway

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57
Q

Does COPD increase or decrease Vd?

A

increases

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58
Q

Does PPV increase or decrease Vd?

A

increases

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59
Q

If dead space increases then what else must increase to maintain a constant PaCO2?

A

Minute ventilation (RR, Vt, or both)

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60
Q

What equation can calculate physiologic dead space?

A

Bohr equation

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61
Q

What equation compares the partial pressure of carbon dioxide in the blood vs. the partial pressure of carbon dioxide in exhaled gas?

A

Bohr’s equation used to determine physiologic dead space

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62
Q

In what region of the lung is the PA02 and V/Q ratio higher?

A

non-dependent region

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63
Q

In what region of the lung is the PAC02 higher but the V/O ratio is lower?

A

dependent region

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64
Q

What is the formula for compliance?

A

compliance = change in volume / change in pressure

65
Q

Does non-dependent or dependent region of a lung have a greater V/Q ratio?

A

non-dependent region

66
Q

Is there increased or decreased vascular resistance in the non-dependent region of a lung?

A

vascular resistance is increased in the non-dependent region of the lung.

67
Q

Does V/Q mismatch usually increase or decrease the A-a gradient?

A

usually increases

68
Q

What does hypoxic pulmonary vasoconstriction minimize?

A

shunt (NOT dead space)

69
Q

Bronchioles constrict to minimize which zone?

A

Zone 1

70
Q

Blood passing through the under ventilated alveoli tends to give up or retain CO2?

A

retain C02

71
Q

In the sitting position is ventilation greater than perfusion at the apex or base?

A

apex

72
Q

What is the most common cause of hypoxemia in the PACU ?

A

atelectasis which is V/Q mismatch

73
Q

Blood passing through the under ventilated tends to do what with CO2?

A

retain C02, and is unable to take in enough oxygen

74
Q

How many times faster does C02 diffuse compared to 02?

A

20 x faster

75
Q

In an overventilated lung the blood passing through the alveoli tends to give off an excessive amount of C02, what happens to 02?

A

even though an excessive amount of CO2 is being eliminated from the blood, it can not take up a proportionate amount of 02. The alveolus can transfer much more CO2 than it can 02.

76
Q

Why is the PAO2-PaO2 gradient large with V/Q mismatch?

A

The lung with V/Q mismatch cannot absorb more oxygen from overventilated alveoli to compensate for under ventilated alveoli.

77
Q

How does the body combat/compensate for a shunt in the lungs?

A

hypoxic pulmonary vasoconstriction reduces pulmonary blood flow to poorly ventilated alveoli.

78
Q

What do type 2 pneumocytes produce and how does it help the alveoli to stay open?

A

They produce surfactant which lowers surface tension and prevents alveolar collapse

79
Q

Do alveoli of different sizes contain different amounts of surfactant?

A

No, every alveoli regardless of size contains the same amount of surfactant

80
Q

Fetal lung maturity can be hastened by what?

A

corticosteroids (betamethasone)

81
Q

Type 2 pneumocytes begin producing surfactant between what weeks of fetal development? When does it peak?

A

production between 22-26 weeks and it peaks around 25-36 weeks

82
Q

closing capacity is what two lung volumes?

A

RV + CV

83
Q

How is a pressure gradient created in the lungs to transfer gas into and out of the lungs?

A

By changing the lung volumes (respiration)

84
Q

What two things can hypoventilation cause?

A

hypercarbia

hypoxemia

85
Q

increasing the concentration of oxygen in a patient who has hypoxemia and hypercarbia will fix the hypoxemia but not the hypercarbia, what can you do to fix the hypercarbia?

A

increase the alveolar ventilation that would remedy both the hypoxemia and the hypercarbia.

86
Q

what is the equation for respiratory quotient?

A

carbon dioxide production divided by oxygen consumption

87
Q

What does a respiratory quotient (RQ) OVER 1 suggest?

What does a respiratory quotient of 0.7 suggest?

A

over 1 = lipogenesis and this occurs with overfeeding.

0.7 suggests lipolysis, this occurs with starvation

88
Q

What are the components of the A-a gradient?

A

difference between alveolar oxygen and arterial oxygen.

89
Q

What cause of hypoxemia can not be fixed with supplemental oxygen?

A

Shunt (pulmonary blood bypassing the alveoli)

90
Q

When breathing room air the normal A-a difference is less than?

A

15 mmHg

91
Q

What three veins bypass the alveolar-capillary interface and deliver deoxygenated blood to the left heart? (contributing to a small physiologic shunt)

A

Thesbesian, bronchiolar, and pleural

92
Q

What does a wide variation between PA02 and PaO2 imply?

A

significant degree of shunt, V/Q mismatch, or diffusion defect across the alveolar-capillary membrane

93
Q

Aging increases the A-a gradient, why?

A

closing capacity increases relative to FRC

94
Q

Why do vasodilators increase A-a gradient?

A

decreased hypoxic pulmonary vasoconstriction

95
Q

atelectasis, pneumonia, bronchial intubation, and intracardiac defect are what kind of shunt? (L-R or R-L)

A

Right to Left shunt

96
Q

True or False

right to left shunt increases A-a gradient?

A

True

97
Q

Why does diffusion limitation increase the A-a gradient?

A

alveolocapillary thickening hinders 02 diffusion

98
Q

What is the formula to find alveolar ventilation? (PA02)

A

PA02 = Fi02 x (Pb - H20) - PaC02/RQ

Pb is barometric pressure which is normally 760mmHg

H20 is usually 47 mmHg

RQ is usually 0.8

99
Q

What is the formula for A-a gradient?

A

You first may have to find your alveolar ventilation which is the formula for PA02.

Your Pa02 should be given to you?

A-a gradient = PA02-Pa02

final answer is in mmHg

100
Q

How many mmHg of A-a gradient causes a 1% increase in shunt?

A

20mmHg

101
Q

if your A-a gradient is 218 mmHg then what percentage shunt do you have?

A

11% roughly

every 20 mmHg = 1%

102
Q

Amount of gas that can be forcibly inhaled after a tidal inhalation is known as?

A

Inspiratory reserve volume

103
Q

Volume of gas that can be forcibly exhaled after a tidal exhalation?

A

Expiratory Reserve Volume

104
Q

Volume of alveolar gas that serves as oxygen reservoir during apnea?

A

Residual volume

105
Q

Volume of gas that remains in the lungs after complete exhalation.

Cannot be exhaled from the lungs

A

Residual volume

106
Q

The volume above residual volume where the small airways begin to close is known as?

A

closing volume

107
Q

Total lung capacity definition?

A

IRV + TV + ERV + RV

108
Q

Vital capacity definition?

A

IRV + TV + ERV

109
Q

Inspiratory capacity definition?

A

IRV + TV

110
Q

Functional Residual Capacity definition?

A

RV + ERV

111
Q

Closing capacity definition?

A

RV + CV

112
Q

tidal volume is x-x ml/kg?

A

6-8 mL/kg

113
Q

vital capacity is x-x mL/kg?

A

65-75 mL/kg

114
Q

Functional residual capacity is xx ml/kg?

A

35 mL/kg

115
Q

all lung volumes are calculated on what type of body weight?

A

ideal body weight NOT total

116
Q

lung volumes are what % smaller in women?

A

25%

117
Q

obstructive lung diseases tend to cause air trapping, what disorders would fall under this?

A

asthma
emphysema
bronchitis

118
Q

if you have an obstructive lung disease what lung volumes will be increased?

A

increased residual volume
closing capacity
total lung capacity

(due to air trapping)

119
Q

What volumes can NOT be measured with spirometry?

A 
residual volume
(total lung capacity and functional residual capacity have residual volume as part of them)

closing volume

capacity

120
Q

What lung volume is the reservoir of oxygen that prevents hypoxemia during apnea?

A

FRC

121
Q

What are some conditions that decrease FRC?

A 
general anesthesia
obesity
pregnancy
neonates
supine
lithotomy
Trendelenburg 
paralysis
inadequate anesthesia 
excessive IV fluid
High Fi02
Reduced pulmonary compliance
122
Q

In what region of the lung is pleural pressure higher and thus the airways in this region close first?

A

dependent region of the lung

123
Q

what is closing volume?

A

the point at which dynamic compression of the airways begins.

Said another way, it is the volume above residual volume where the small airways begin to close during expiration.

124
Q

Factors that increase closing volume (CLOSE-P)?

A 
COPD
Left ventricular failure
Obesity
Supine position
Extremes of age
Pregnancy
125
Q

What is closing capacity?

A

closing volume + residual volume = CC

absolute volume of gas contained in the lungs when the small airways begin to collapse

126
Q

FRC is greater than closing capacity when?

A

under normal circumstances

127
Q

When does airway closure occur during tidal breathing?

A

when closing capacity is greater than FRC

128
Q

what tactic can we use to increase FRC relative to CC?

A

PEEP

129
Q

What are some consequences of aging related to the lungs?

A

increased FRC
Increased closing capacity
increased residual volume
decreased vital capacity

130
Q

On average how much oxygen is dissolved in the blood and how much is reversibly bound with hemoglobin?

A

3% dissolved in plasma

97% reversibly binds with hemoglobin

131
Q

each gram of hemoglobin molecule can carry a theoretical maximum of how many mL of molecular oxygen?

A

1.39 mL

132
Q

Oxygen bound to hemoglobin formula?

A

(1.34 x Hgb x Sa02)

133
Q

Ca02 formula?

A

(1.34 x Hgb x Sa02) + (Pa02 x 0.003) = 20 mL 02 per dL

134
Q

Normal Hgb and Hct values for Male and Female?

A

Male 15g/dL and 45%

Female 13g/dL and 39%

135
Q

Oxygen dissolved in plasma formula?

A

(Pa02 x 0.003)

136
Q

solubility coefficient for oxygen is?

A

0.003 mL/dL/mmHg

137
Q

What is Henrys law?

A

concentration of gas in a solution is directly proportional to the partial pressure of the gas above the solution

138
Q

is oxygen more or less soluble than C02 in the blood?

A

20 x less soluble than C02

139
Q

What does Ca02 tell you?

A

HOW MUCH 02 is contained in the blood (bound to hgb + dissolved in the blood)

140
Q

What does DO2 tell you? ( oxygen delivery)

A

HOW FAST a quantity of 02 is delivered to the tissues

141
Q

Ca02 stands for?

A

Oxygen content

142
Q

formula for oxygen delivery? (DO2)

A

DO2 = Ca02 x cardiac output x 10

143
Q

V02 is what?

A

oxygen consumption

144
Q

Numbers you must know, what is VO2 in mL/kg/min and ml/min assuming a 70kg male?

A

V02 = 3.5mL/kg/min

V02 is approx. 250mL for a 70 kg male

145
Q

formula for VO2?

A

VO2 = cardiac output x (Ca02 - Cv02) x 10

146
Q

increased affinity for 02 is what kind of shift?

A

left shift

147
Q

What is P50?

A

P50 is the Pao2 where hgb is 50% saturated by oxygen

148
Q

What shifts the oxyhgb curve to the left?

A

decreased temp.
decreased 2,3-DPG
decreased CO2
decreased H+

increased pH
increased HgbMet
increased HgbCO
increased Hgb F

149
Q

What shifts the oxyhgb curve to the right?

A

increased temp
increased 2,3-DPG
increased CO2
increased H+

decreased pH

150
Q

What is the partial pressure of oxygen at P50?

A

26.5

151
Q

What two molecules cause Hgb to release oxygen?

A

CO2 and hydrogen ions

152
Q

When is 2,3-DPG produced?

A

During RBC glycolysis

153
Q

Tell me the difference between the Bohr effect and the Haldane effect?

A

Bohr describes oxygen carriage and Haldane is just the opposite.

Bohr says that C02 and decreased pH cause the erythrocyte to release oxygen while Haldane says that oxygen causes the erythrocyte to release CO2.

154
Q

deoxygenated hemoglobin can carry more CO2, what effect is that?

A

Haldane effect

155
Q

The more oxygen carried by hemoglobin the less CO2 that can be carried, is this a left or right shift on the carbon dioxide dissociation curve?

A

left is a love for oxygen just like the oxyhemoglobin curve.

156
Q

The carbon dioxide dissociation curve explains what?

A

When hemoglobin is oxygenated in the lungs it has a decreased affinity for C02 and this allows for unloading of CO2 and CO2 to be excreted from the body.
If the hemoglobin is deoxygenated then it has an affinity for CO2 and in the systemic capillaries CO2 is picked up and transported.

157
Q

What value = hypercapnia?

A

PaCO2 > 45 mmHg

158
Q

CO2 production / alveolar ventilation describes what formula?

A

PaCO2 formula

159
Q

What can cause hypercapnia?

A

increased CO2 production or decreased CO2 elimination

APEX (18 decks)

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