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Physiology > Pulmonary 2 > Flashcards

Pulmonary 2 Flashcards

1
Q

HIGH PRESSURE
LOW FLOW
Branches of thoracic aorta
Systemic arterial blood

Trachea, bronchial tree, supporting tissues of the lungs

1-2% of total cardiac output

A

Bronchial arteries

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2
Q 
LOW PRESSURE
HIGH FLOW
Venous blood from the right ventricle
Pulmonary capillaries for gas exchange
5cm
Thin walls, large diameter -> large compliance 7 ml/mmHg
A

Pulmonary artery

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3
Q

Blood volume in the lungs

A

450 ml 9% of total blood volume

70ml is in the pulmonary capillaries

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4
Q

Decreased alveolar oxygen reduces local alveolar blood flow and regulates pulmonary blood flow distribution

Alveolar O2 below 70 percent of normal (73mmHg)

Alveolar hypoxia -> vasoconstriction of adjacent pulmonary vessels

To redistribute blood flow where it is most effective

A

Hypoxic vasoconstriction

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5
Q

In the upright position, when the effects of gravity are apparent, the lung apices are relatively

A

underperfused owing to low arterial hydrostatic pressure at lung apices

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6
Q

Whereas in the upright position, the lung bases are relatively

A

overperfused

for this reason, pulmonary blood flow is often described as being divided into three different zones

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7
Q

Palveoli > Partery > P vein

Zone:

A

Zone 1

Lung apices are relatively underperfused

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8
Q

Partery > Palveoli > Pvein

A

Zone 2

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9
Q

Partery> P vein> Palveoli

A

Zone 3

Lung bases are relatively overperfused

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10
Q

No blood flow during the cardiac cycle
A pathologic condition that does not normally occur in the healthy lung

The lack of perfusion in this zone pulmonary blood flow quickly leads to tissue necrosis and lung damage

Occur when hydrostatic arterial and venous pressures are lower than alveolar pressure

A

Zone 1

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11
Q

Seen with severe hemorrhage and positive-pressure ventilation

Occur in lung apices, where arterial hydrostatic pressure are reduced relative to the pressures in arteries supplying the lower lung fields

Under these conditions, the blood vessel is completely collapsed and there is no blood flow during either systole or diastole

A

Zone 1 blood flow

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12
Q

This zone has intermittent blood flow during the cardiac cycle
No blood flow during diastole

This is typically exhibited by the upper 2/3 of the lungs
Alveolar pressures cause collapse of pulmonary capillaries during diastole, but pulmonary capillary pressures during systole exceed alveolar pressures, resulting in perfusion during systole

No blood flow during diastole because of collapse of pulmonary capillaries

A

Zone 2 blood flow

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13
Q

This zone has continuous blood flow during the cardiac cycle

This pattern of blood flow is characteristic of the lung bases which are situated below the heart

Pulmonary capillary pressures are greater than alveolar pressures during systole and diastole, which means that the pulmonary capillaries remain patent throughout the cardiac cycle.

A

Zone 3 blood flow

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14
Q

Causes by any factor that increases fluid filtration out of the pulmonary capillaries or impede pulmonary lymphatic function

Most common causes:

LSHF of mitral valve disease
Damage to the pulmonary blood capillary membranes

A

Pulmonary edema

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15
Q

Normal pleural fluid

A

50 ml

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16
Q

Excess fluid is pumped away by lymphatics:

A

Mediastinum
Lateral surface of parietal pleura
Superior surface of the diaphragm

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17
Q

This comes from the pumping of fluids out of the pleural space by the lymphatics

A

Negative pressure

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18
Q

Blockade of lymphatic drainage from the pleural cavity
Cardiac failure
Greatly reduced plasma colloid osmotic pressure
Infection or any other cause of inflammation

A

Pleural effusion

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19
Q

Important for efficient gas exchange

For gas exchange to occur efficiently at the pulmonary membrane, pulmonary ventilation and perfusion should be well matched

Optimal matching minimizes unnecessary ventilation of nonperfused regions and perfusion of nonventilated areas

Inefficient to perfuse unventilated alveoli or ventilate nonperfused alveoli

A

V/Q matching

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20
Q

V/Q at rest

A

0.8 with alveolar ventilation of about 4L/m and cardiac output of 5L/minute

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21
Q

The lung apices at rest are

A

underperfused and relatively overventilated (V/Q ratio = 3.3) but compared with the lung bases, they do not receive as much perfusion

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22
Q

The high V/Q ratio indicated discrepancy between the

A

amount of blood flow and ventilation

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23
Q

Conversely, the lung bases at rest are relatively

A

overperfused (V/Q ratio, 0.6)

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24
Q

Optimal matching of pulmonary ventilation and perfusion is achieved by

A

hypoxia-induced vasoconstriction and by changes in response to exercises

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25
Q

Mechanisms of Maintaining V/Q Matching

A

Hypoxia-induced vasoconstriction

Changes during exercise

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26
Q

Shunts blood to better-ventilated lung segments

A

Hypoxia-Induced Vasoconstriction

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27
Q

Recruitment

Distention

A

Changes during exercise

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28
Q

In most capillary beds, hypoxia stimulates vasodilation (eg. myogenic response of autoregulation)

In pulmonary vasculature, hypoxia stimulated

A

vasoconstriction of pulmonary arterioles, essentially preventing the perfusion of poorly ventilated lung segments (eg. as might occur in pulmonary disease)

This allows the lungs to optimize V/Q matching for more efficient gas exchange

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29
Q

Only about 1/3 of the pulmonary capillaries are open at rest.

Recruitment: opening of previously closed pulmonary capillaries because of increased pulmonary arterial pressures as may occur with exercise.

During exercise, additional capillaries are

Capillaries that are already open dilate to accomodate more blood

A

Open (recruitment) because of increased pulmonary artery blood pressure

Distention

30
Q

During exercise, ventilation and perfusion (and hence gas exchange) occur more frequently efficiently because

A

With increased cardiac output, blood flow is increased to the relatively underperfused lung apices

Ventilation is increased to the relatively underventilated lung bases.
V/Q matching occurs more efficiently during exercise.

31
Q

Blood that bypasses the lungs or for another reason does not participate in gas exchange

A

Shunt

32
Q

Two types of shunts:

A

Anatomic shunt

Physiologic shunt

33
Q

Blood flow bypasses lungs

Ex
Fetal blood flow
Intracardiac shunting (L->R, R->L)

A

Anatomic shunt

34
Q

Blood flow to unventilated portions of lungs

Ex
Bronchial artery circulation
Pneumonia
Pulmo edema

A

Physiologic shunt

35
Q

Oxygen content of systemic arterial blood at sea level

A

200 ml O2

197 ml from O2 bound to hemoglobin (98.5%)
3 ml from O2 physically dissolved (1.5%)

Cardiac output = 5L/min
O2 carried to tissues/min = 5L/min x 200 ml O2/L
= 1000 ml O2/min

36
Q

SpO2 of 90% = pO2

A

pO2 60 mmHg

37
Q

Any increase in pO2 will cause minimal increase in spO2

A

Shift to the right

38
Q

A slight decrease in pO2 causes a profound change in SpO2

A

Shift to the left

39
Q

Onset of cyanosis

A

SpO2 85%

40
Q

Bohr Effect

Increased O2 delivery to tissues when CO2 and H+ shift O2-Hgb dissociation curve

A

Shift to the right

41
Q

EPO is produced in the

A

peritubular capillaries of the kidneys

42
Q

Strongest stimulus of EPO

A

Hypoxia

43
Q

Composition of air:

A

79% nitrogen
21% oxygen
0% CO2

44
Q

In a mixture of gases, each gas exerts a partial pressure proportional to its mole fraction

Total pressure =

A

sum of the partial pressures of each gas

760 mmHg

45
Q

Oxygen binding curve is

A

sigmoidal for both Hb-F and Hb-A

46
Q

Has higher affinity for oxygen because it binds to DPG less strongly

A

Hb-F

47
Q

Factors that lower oxygen bindng to hemoglobin

A 
Dec pH
Inc CO2
Inc H ion concentration 
Inc BPG/DPG
Inc temperature
48
Q

Conditions where oxygen is low, O2-Hgb curve shifts to the right such that

Type of effect

A

more oxygen is readily available for distribution to the peripheral tissues

Bohr Effect

49
Q

Shift to the right
HCO3 leaves the RBCs into the plasma
HCO3 is replaced by chloride
Chloride shift

A

Chloride shift

Partial pressure of CO2

50
Q

Effect of allosteric factor to oxygen-binding curve

A

Increase in temperature increases O2 release

Shift to the right

51
Q

Hypothermia causes shift to the

A

Left because it reduces oxygen requirements due to slow cellular metabolism

52
Q

Increase 2,3 DPG decreases O2-Hb affinity leading to a shift to the

A

right

53
Q

One DPG molecule binds to each Hb and stabilizes T form promoting

A

O2 release

54
Q

Relaxed form Hgb

A

Binds better to O2

55
Q

Tense/taut form

A

Decreased binding with O2

Shift to the right

56
Q

Has an affinity for Hb 200 times that of oxygen
Once bound, does not readily dissociate
Affects O2 transport

A

Carbon monoxide

57
Q

ETC happens in

A

Inner mitochondria

Oxidative phosphorylation

58
Q

Complex IV involves

A

Cytochrome oxidase

59
Q

Inhibits cytochrome oxidase

A

carbon monoxide

Cyanide

60
Q

Final acceptor in ETC

A

oxygen

61
Q

Binds only to metHb
Prevents reduction to active form
Impairs ability of blood to transport O2

A

Cyanide

62
Q

Drug associated with cyanide poisoning

A

sodium nitroprusside

63
Q

Antidote for cyanide poisoning

A

Thiosulfate
Hydroxocobalamin
Amyl nitrite

64
Q

Describes the relationship between the rate of diffusion and the three factors that affect diffusion

The rate of diffusion is proportional to both the surface area and concentration difference and is inversely proportional to the thickness of the membrane

A

Fick’s Law of Diffusion

65
Q

Receives entire cardiac output

Has markedly lower pressures

Smaller pressure drop across the pulmonary bed

A

Pulmonary circulation

Mean = 15

66
Q

Most perfused area of the lung

A

Base

Zone 3

67
Q

Most ventilated area of the lung

A

Apex

68
Q

Increased hydrostatic pressure leads to

A

Edema

69
Q

Secretion in pulmonary edema

A

Frothy

Blood tinged/pinkish secretion

70
Q

First line drug for pulmonary edema

A

Furosemide

71
Q

Transudative pleural fluid

A

Low albumin hypoalbuminemia
Liver cirrhosis
Nephrotic syndrome

72
Q

Most common cause of V/Q mismatching

A

Hypoxia

Physiology (23 decks)

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