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A&P Test 3 > Respiratory 3 > Flashcards

Respiratory 3 Flashcards

1
Q

lung blood flow when supine

A

uniform throughout the lung

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2
Q

lung blood flow when standing

A

it is lowest at apex (zone 1) and highest at the base of the lung(zone 3)

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3
Q

why is the distribution of blood flow in the lung uneven

A

it is uneven due to the effects of gravity

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4
Q

West zone 1- what is blood flow

A

Blood flow is the lowest

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5
Q

west zone 1 pressures

A

alveolar pressure>arterial pressure>venous pressure.

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6
Q

west zone 1- should it exist, it exist when?

A

no, can occur if arterial blood pressure decreases as a result of hemorrhage or if alveolar pressure is increased because of positive pressure ventilation. (v/q=8)

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7
Q

factors that expand zone 1

A

decrease pa pressure (shock) pul hypOtension
increase alveolar pressure (peep)
occlusion of blood vessel (pe)

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8
Q

factors that reduce zone 1

A

increase pa pressure - pul htn

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9
Q

what is blood flow like at west zone 2

A

blood flow is medium

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10
Q

what is blood flow at west zone 3

A

blood flow is highest

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11
Q

west zone 2 pressures

A

arterial pressure>alveolar pressure>venous pressure

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12
Q

west zone 3 pressures

A

arterial pressure>venous pressure>alveolar pressure

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13
Q

why in zone 2 is arterial pressure greater than alveolar pressure?

A

because blood flow is driven by the difference between arterial pressure and alveolar pressure (water fall zone)

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14
Q

in zone 2 why does arterial pressure progressively increased

A

because of gravitation effects on hydrostatic pressure.

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15
Q

in zone 3 how is blood flow driven?

A

by the difference between arterial and venous pressure as in most vascular beds.

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16
Q

arterial pressure is highest at zone 3 why is that

A

due to gravitational effects and venous pressure is finally increased to the point where it exceeds alveolar pressure

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17
Q

At the apex what is VQ?

A

( highest V/Q) , PO2 is highest and PCO2 is lowest because gas exchange is more efficient

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18
Q

At the base what is vq

A

( lowest V/Q) ,PO2 is lowest and PCO2 is highest because gas exchange is less efficient

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19
Q

In lung diseases what is vq

A

V/Q inequalities are more pronounced than in the normal lung; consequently , there can be severe hypoxia and modest hypercapnia

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20
Q

V/Q ratio

what is it?

A

Is the ratio of alveolar ventilation (V) to pulmonary blood flow (Q) . Matching V and Q is important to achieve the ideal exchange of O2 and CO2

Ideally , ventilation is matched to perfusion (i.e. V/Q=1) for adequate oxygenation to occur efficiently

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21
Q

what is normal vq?

A

0.8

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22
Q

what is the normal ventilation

A

4l/m

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23
Q

what is the normal perfusion

A

5l/m

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24
Q

ventilation is lowest where?

A

is also lowest at the apex and highest at the base, but the regional differences for ventilation are not as great as for perfusion

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25
Q

Blood flow is lowest where?

A

at the apex and highest at the base because of gravitational effects.

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26
Q

vq at apex

A

~3

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27
Q

vq at base

A

~0.8

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28
Q

explain regional differences for p02 and pco2

A

As a result of the regional differences in V/Q ratio, there are corresponding differences in the efficiency of gas exchange and in pulmonary capillary PO2 and PCO2. Regional differences for PO2 are greater that those of PCO2

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29
Q

V/Q ratio in airways obstruction

A

If the airways are completely blocked (e.g. by a piece of steak caught in the trachea), than ventilation is zero. If blood flow is normal then V/Q is zero, which is called a shunt.

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30
Q

V/Q ratio in airways obstruction- tell me about the gas exchange?

A

There is no gas exchange in a lung that is perfused but not ventilated

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31
Q

V/Q ratio in airways obstruction-

A

The PO2 and PCO2 of pulmonary capillary blood (and therefore, of systemic arterial blood) will approach their values in mixed venous blood

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32
Q

V/Q ratio in airways obstruction- what happens to the aa gradient

A

There is an increased A-a gradient (calculated by using alveolar gas equation)

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33
Q

V/Q ratio in pulmonary embolism

A

If the blood flow to a lung is completely blocked (PA embolism), then the blood flow to lung is zero. If ventilation is normal , then V/Q is infinite (), which is called dead space

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34
Q

V/Q ratio in pulmonary embolism

A

There is no gas exchange in a lung that is ventilated but not perfused. The PO2 and PCO2 of alveolar gas will approach their values in inspired air

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35
Q

At V/Q zero or infinity what happens to gas exchange

A

NO gas exchange occurs resulting hypoxemia

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36
Q

slide 18

A

slide 18

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37
Q

V/Q = infinite =?

A

=blood flow obstruction. Assuming <100% dead space, 100% O2 improves PO2

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38
Q

V/Q of 0 =

A

V/Q of 0 = airway obstruction (shunt), In shunt, 100% oxygen does not improve PO2

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39
Q

PULMONARY EDEMA and causes

A 
Fluid in alveoli and interstitial space
Causes
Left-sided heart failure
Infections
Noxious gases like Cl2 , SO2
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40
Q

Pleural Effusion

A

Pleural Effusion: flooding of large amount of fluid in the pleural space

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41
Q 
OUTWARD  Forces (mmHg)
Capillary pressure
A

7mmhg

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42
Q 
OUTWARD  Forces (mmHg)
interstitial osmotic pressure
A

14mmhg

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43
Q

OUTWARD Forces (mmHg)negative interstitial fluid pressure

A

8mmhg

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44
Q

OUTWARD Forces (mmHg)total

A

29

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45
Q 
INWARD Forces  (mmHg)
Plasma protein osmotic pressure
A

28mmhg

46
Q

Mean Filtration Pressure

A

29-28= +1 mmHg

47
Q

Partial Pressure ‘P’ of gases

A

It is the pressure exerted by any one gas in a mixture of gases and equal to the total pressure times the fraction of the total amount of gas.

48
Q

PO2 (Partial Pressure of Oxygen)

what is it ensuring the lungs are able to do?

A

is oxygen gas dissolved in the blood. It primarily measures the effectiveness of the lungs in pulling oxygen into the blood stream from the atmosphere

49
Q

Elevated PO2 levels are associated with

A

Increased oxygen levels in the inhaled air

Polycythemia

50
Q

Decreased PO2 levels are associated with

A 
Decreased oxygen levels in the inhaled air 
Anemia 
Heart decompensation 
Chronic obstructive pulmonary disease 
Restrictive pulmonary disease 
Hypoventilation
51
Q

PO2=

A

PO2=160 mmHg (760x0.21=160)

52
Q

PN2=

A

PN2=600 mmHg (760x0.79=600)

53
Q

Dalton’s law of partial pressure

A

Partial pressure = Total pressure  fractional gas pressure

54
Q

In humidified air at 37C, consider the PH2O which is 47 mmHg

A

PO2 = (760-47) x 0.21= 150 mmHg

55
Q

O2 Bound to Hemoglobin

how much 02 is carried on each gram of Hb

in 100ml what is the normal hemoglobin concentration amount

A

1.34 x 15 = 20.1 ml O2/100 ml of blood

The amount of O2 carried by each gram of fully saturated (100%) Hb = 1.34 ml O2 per gram of Hb
Normal Hb = 15 g/100ml

56
Q

henrys law

A

The amount of gas dissolve in a solution (e.g. in blood) is proportional to its partial pressure (Henry Law)

57
Q

Dissolve [ O2 ] =

A

100 mmHg x 0.03 mL O2/L / mmHg
= 0.3 mL O2/100 mL blood

PO2 x solubility of O2 in blood

58
Q

DIFFUSION rate of 02 and co2

what pressure does the diffusion rate depend on?

what in the lungs does it depend on?

A

Diffusion rate of O2 and CO2 depend on the partial pressure difference across the respiratory membrane and the area (total number of intact alveoli) available for diffusion.

59
Q

PO2(alveoli) >

A

PO2(blood)

60
Q

PCO2(blood) >

A

PCO2(alveoli)

61
Q

tell me ficks law

A

slide 33

62
Q

Ideally PAO2-PaO2 gradient should be

A

zero. However normal lungs shows some V/Q mismatch.

63
Q

Alveolar-arterial (PAO2-PaO2) gradient normal value??

A

Normal value is 5 to 15 mmHg.

64
Q

Alveolar-arterial PCO2 difference is

A

2-10 mmHg

65
Q

why do we calculate the alveolar-arterial po2 difference?

A

Alveolar-arterial PO2 difference calculation is used to differentiate between causes of hypoxemia. (extrapulmonary vs. intrapulmonary).

66
Q

A-a gradient =

A

PAO2 – PaO2

67
Q

PAO2 =

A

alveolar PO2 (calculated by multiplying O2 percentage in inspired gas mixture by 6)

68
Q

PaO2 =

A

arterial PO2(calculated by multiplying O2 percentage in inspired gas mixture by 5)

69
Q

normal aa gradient why are they approximately equal

A

Since O2 normally equilibrates between alveolar gas and arterial blood, PAO2 is approximately equal to PaO2

70
Q

when is A-a gradient increased?

A

if O2 does not equilibrate between alveolar gas and arterial blood (e.g. diffusion defect, V/Q defect, right-to-left shunt)

71
Q

In hypoxemia (PaO2 < 60 mmHg normal gradient means?

A

if either PAO2-PaO2 or PACO2-PaCO2 gradient is normal then hypoxemia is due to hypoventilation.

72
Q

In hypoxemia (PaO2 < 60 mmHg) higher gradient means?

A

if either PAO2-PaO2 or PACO2-PaCO2 gradient is higher then hypoxemia is due to V/Q mismatch.

73
Q

In airways obstruction what happens to vq mismatch

A

In airways obstruction, no air is getting in and blood is shunting; creating a V/Q mismatch that will increase the A-a gradient (calculated by using alveolar gas equation)

74
Q

In hypoventilation what happens to vq mismatch

A

So hypoventilation differs from airway obstruction (no ventilation). In hypoventilation some air is getting in and equilibrates with the blood at a low level, therefore A-a gradient will stay normal

75
Q

hypoventilation and equilibration of 02

A

Hypoventilation causes hypoxemia by decreasing alveolar PO2 (less fresh air is brought into alveoli). Equilibration of O2 is normal, and systemic arterial blood achieves the same (lower) PO2 as alveolar air. PAO2 and PaO2 are nearly equal (although low) and the A-a gradient is normal. In hypoventilation ,breathing supplemental oxygen raises arterial PO2 by raising the alveolar PO2

76
Q

Normal A-a gradient

A

suggests that the lungs are quite normal and the problem is somewhere else, e.g. hypoventilation or breathing in thin air at high altitude

77
Q

High (e.g. 30 mmHg) A-a gradient always associated with problems with lung or heart. In lung, there may be problems with:
Ventilation:

A 
No ventilation (e.g. in airways obstruction) 
Perfusion OK, but produces an intrapulmonary shunt: aspiration pneumonia, atelectasis ,ARDS
78
Q

High (e.g. 30 mmHg) A-a gradient always associated with problems with lung or heart. In lung, there may be problems with:
PERFUSION:

A

Ventilation OK, but no perfusion produces an increase in dead space as in pulmonary embolism

79
Q

High (e.g. 30 mmHg) A-a gradient always associated with problems with lung or heart. In lung, there may be problems with:
DIFFUSION:

A 
Interstitial fibrosis (diffusion block)
Sarcoidosis
Scleroderma
80
Q

High (e.g. 30 mmHg) A-a gradient always associated with problems with lung or heart. In lung, there may be problems with:
SHUNTING

A

Right-to-left shunt

Intrapulmonary or cardiac

81
Q

O2 binding capacity of blood

what does it depend on?

A

HB concentration in blood

82
Q

O2 binding capacity of blood

how many mls?

A

20.1ml02/100ml

83
Q

is 02 binding capacity of blood limited?

A

its limited by the amount of 02 that can be carried in blood. the maximum amount of 02 that can be bound to Hb in blood at 100% saturation

84
Q

02 content of blood

A

Is the total amount of O2 in blood, including bound and dissolved O2
Depends on the Hb concentration, PO2 and P50 of Hb
O2 content = (O2 binding capacity x%Sat.) + Dissolved O2

85
Q

Methemoglobinemia

A

In hemoglobin iron is in ferrous from (Fe++) while in methemoglobin; iron in ferric form (Fe+++)
Methemoglobin does not bind to O2 as readily, but has  affinity for CN-

86
Q

In methemoglobinemia what happens to 02 transport

A

causes defective 02 transport resulting in low saturation

87
Q

what can cause methemoglobinemia

A

nitrites, benzocaine, metabolites of prilocaine

88
Q

treatment for methemoglobinemia

A

IV methylene blue converse ferric Fe+++ to ferrous form ++

89
Q

Cyanide poisoning causes

A 
Causes
Nitroprusside (releases CN ions)
Bitter almond oil
KCN
Wild cherry syrup
90
Q

cyanide poisoning s/s

A

Tachycardia, hypotension, coma , acidosis, increase venous O2, rapid death

91
Q

cyanide poisoning treatment

A

To treat cyanide poisoning, give sodium nitrite and amyl nitrites to oxidize Hb to metHb (inducing methemoglobinemia) which binds cyanide, allowing cytochrome oxidase enzyme to go free and function.
Use thiosulfate to bind this cyanide, forming thiocynate, which is excreted by kidneys.

92
Q

what is can sodium NitroPrusside cause? two things?

A

Sodium NP can cause methemoglobinemia as well as cyanide poisoning. Watch the S/S and give treatment accordingly.

93
Q

O2 is carried in blood in two forms

what two forms and what percent do they carry oxygen?

A

Bound to Hb ( 97%) in RBCs – chemical form
Dissolve form ( 3%) in plasma – physical form
Only form of O2 that produces its partial pressure in blood (PO2)
Not enough to meet the demand

94
Q

Hb binds with 02 to form oxyhemoglobin how does it do that?

A

rapidly and reversibly!

95
Q

what is 02 tension considered

A

O2 tension is the driving force for the chemical reaction—Hb + O2 –HbO2 ( increase PO2 increase Affinity♥of Hb for O2)

96
Q

how does binding of the first 02 molecule affect the binding of the second 02 molecule.?

A

Binding of the first O2 molecule increases the affinity for the second O2 molecule and so forth. This change in affinity facilitates the loading of O2 in the lungs (flat portion of curve) and the unloading of O2 at the tissue (steep portion of curve)

97
Q

In the Lungs (Loading Zone) “flat portion”

A

Alveoli have high PO2 –100 mmHg (Affinity♥)
The very high affinity of Hb for O2 at PO2 of 100mmHg facilitates the diffusion process
O2 is loaded from alveoli to Hb
The curve is almost flat (shoulder) when the PO2 is between 60-100mmHg. Thus, human can tolerate changes in PO2 without compromise of the O2-carrying capacity of Hb.( Below PO2 of 60 mmHg there will be free fall of Sat.)

98
Q

In the peripheral tissues (Unloading Zone) “steep portion”

A

Tissues have low PO2 – 40 mmHg (decreased Affinity♥)

O2 is unloaded (released) from Hb to tissue

99
Q

shift to the right

A 
more 02 delivered
acidosis
increase c02
increase temp
increase 2,3 dpg
increased exercise
100
Q

shift to the left

A 
love 02
alkalosis
decrease c02
decrease temp
decrease 2,3 dog
decrease exercise
101
Q

Bohr effect

A

The shift of oxyHb curve in response to increase or decrease PCO2 is

Shift the curve to right, decreases the affinity of Hb for O2 and facilitating the unloading/delivery/release of O2 in the tissues

102
Q

Utility of Bohr Effect

A

At tissue level CO2 diffuses into the blood that shifts the curve to right more release of O2
At lungs CO2 diffuse from blood into alveoli that shifts the curve to left  more loading of O2

103
Q

blood flow -apex

A

lowest

104
Q

blood flow base

A

highest

105
Q

ventilation apex

A

lower

106
Q

ventilation base

A

higher

107
Q

vq apex

A

highest

108
Q

vq base

A

lower

109
Q

apex 02

A

highest

110
Q

base 02

A

lowest

111
Q

pco2 base

A

higher

112
Q

pco2 apex

A

lower

A&P Test 3 (4 decks)

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