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1

A-a gradient equation

A-a = PAO2 - PaO2

2

what do you use to calculate the A-a gradient

alveolar gas equation and values from the arterial blood gas

3

the 5 main mechanisms of hypoxemia fall under what 2 main categories

1. not enough oxygen getting into alveoli

2. not enough oxygen transferred into the capillary bed

4

with not enough oxygen getting into the alveoli, what is the A-a gradient

normal A-a gradient

5

with not enough oxygen transferred into the capillary, what is the A-a gradient

elevated A-a

6

what causes not enough oxygen getting into the alveoli

- low atmospheric pressure (ex high altitude)
- hypoventilation (ex heroin overdose)

7

what causes not enough oxygen transferred into the capillary blood

- ventilation-perfusion mismatch (ex atelectasis)
-right to left shunting (ex atrial septal defect)
- diffusion defects (ex pneumonia)

8

pulmonary ventilation

inflow and out flow of air b/w the atmosphere and lung aveoli

9

external respiration

diffusion of oxygen and carbon dioxide between the aveoli and the blood

10

internal respiration

transport of O2 and CO2 in the blood and body fluids to and from the body's tissue and cells

11

what systems regulate ventilation and respiration?

CNS effects and Peripheral effects

12

lungs can be expanded and contracted in 2 ways. what are they?

1. downward and upward movement of diaphragm (normal quiet breathing)
2. elevation and depression of chest cavity (increase thoracic volume by 20%)

13

what are the 3 pressures that cause the movement of air in and out of the lungs

pleural
alveolar
trans pulmonary

14

what is pleural pressure

pressure of the fluid in the thin space between the lung pleura and chest wall pleura

15

what is another name for pleural pressure

intrapleural pressure

16

at rest, what is the pleural pressure

-5 cm H2O
which is negative suction

17

what is the pleural pressure during inspiration

increases to -7 cm H2O

18

what is alveolar pressure

pressure inside the lung alveoli

19

what is another name for alveolar pressure

intrapulmonary pressure

20

when is the alveolar pressure 0 cm H2O

when glottis is open and no air is moving the alveolar pressure

21

During inspiration, what is the alveolar pressure?

decreases to -1 cm H2O and 0.5 liters of air enters in 2 seconds

22

during experation, what is the alveolar pressure

alveolar pressure increases to +1 cm H2O and forces 0.5 liters of air out of lung

23

transpulmonary pressure is also known as "___ ____ pressure" which measures....

Elastic recoil pressure

the measure of the elastic force in the lungs

24

Pulmonary blood flow represents ____ and is usually the blood flow measured to determine ____ via the Swan Ganz catheter

represents total cardiac output and usually the blood flow measured to determine total cardiac output via the Swan Ganz catheter

25

at rest, the entire blood volume of the body passes through the ....

pulmonary circulation every 1 to 2 minutes and more frequently during exercise

26

in an adult at rest, the capillary blood volume is about how much and what does it approximate?

capillary blood volume is 140-200 ml

approximates the right heart stroke volume

27

The lung has dual circulation. what are the 2 circulations?

pulmonary circulation and bronchial circulation

28

what kind of vasculature is pulmonary circulation and what is it involved in?

a low-pressure, high-volume vasculature

involved in gas exchange that perfuses alveoli

29

what is bronchial circulation and what does it provide?

a high-pressure, low volume system

provides nutrients and gas exchange for the bronchial tree and conducting airways

30

Bronchial circulation is part of the ___ ____ and receives about 2% of the CO from the ___ ____

part of the systemic circulation and receives about 2% of the total CO from the left ventricles

31

where do the bronchial arteries arise from?

branches of the aorta, intercostal subclavian, or internal mammary arteries

32

how much does bronchial veins drain and from where?

about 1/3 of the venous drainage from the bronchial circulation via the azygos, hemiazygos, and intercostal veins

33

bronchial venous blood returns back to where

the right atrium

34

about 2/3 of the bronchial capillary blood is thought to drain into where?

anastomoses or communicating vessels that empty into the pulmonary veins to return to the left atrium

35

what does the bronchial capillary blood draining into the left atrium communication provide?

small volume of poorly oxygenated bronchial venous blood to the freshly oxygenated blood in the pulmonary vein

36

Pulmonary circulation is in series with the _____ circulation, therefore blood flow is _____

in series with systemic circulation, therefore blood flow is the same in both

37

how do the vessel walls in the pulmonary circuit compare to the walls in the systemic circuit

Vessel walls of the pulmonary vasculature are much thinner and contain less smooth muscle compared to segments in the systemic circulation

38

Structurally, the ____ _____ more closely resemble systemic veins than arteries

pulmonary arteries more closely resemble systemic veins

39

speaking of high flow rates, does the pulmonary or systemic circulation have lower high flow rates?

pulmonary vascular pressures are considerably lower

40

average PA pressure

13-19 mmHg

41

what causes the lower pulmonary vascular pressure?

the lack of high resistance arterioles

-affects blood flow distribution in the lung

42

Fick principle for cardiac output

the amount of O2 uptake or consumption by the body per minute is equal to the cardiac output times the difference in oxygen content b/w arterial and mixed venous blood

43

The lung is greatly designed for gas exchange, but it is ideally suited for other functions unrelated to gas exchange because....

the large blood volume that passes through the lung each minute

-immense capillary surface available for metabolism

44

what are the four functions of pulmonary

1. gas exchange
2. blood filter
3. blood reservoir
4. metabolism of circulating substances

45

what does the meshwork of capillary vessels do to act has a blood filter in the lungs?

trap emboli and large particles to keep from reaching the coronary or systemic vasculature

46

how are emboli trapped by pulmonary vessels later removed?

enzymatic processes, macrophage ingestion, or absorption into the lymphatic system

47

how do the vessels of the pulmonary system help function as a blood reservoir?

vessels are very compliant and easily distant

since vessels are an extension of the left atrium, they act as a blood reservoir, supplying blood to the left ventricle and maintaining output

48

pulmonary vessels contain how much blood

450-900 ml of blood

49

which cells in the lumen are involved in the uptake or metabolic conversion of several vasoactive substances in the circulation

endothelial cells

50

what are some things that the lungs release that help with metabolism of circulating substances

-biologically active compounds into circulation
-histamine
-prostaglandins,
-leukotrienes
-platelet activating factor
-heparin
-serotonin
-nitric oxide

51

where are mast cells found

-in most tissues of body, especially those that interact with the environment
-skin, lungs, GI tract, mouth, nose, blood brain barrier

52

when do mast cells detect and respond to?

-foreign substances

53

when triggered, what do mast cells release?

-histamine
-prostaglandins
-heparin
-tryptase
-cytokines

54

Pulmonary artery branches rapidly give rise to nearly

300 billion pulmonary capillaries

55

gas exchange between the _____ and ____ occurs within the lung capillaries

alveolar gases and blood occurs within the lung capillaries

56

gas exchange between alveoli and pulmonary capillary blood is by

simple diffusion

57

O2 diffuses from the ___ to the ____
CO2 diffuses from the ____ to the ____

O2 diffuses from the alveolus to the pulmonary capillary blood
CO2 diffuses from the pulmonary capillary to the alveolus

58

what is the alveolar-arterial gradient?

a measure fo the difference between the alveolar concentration (A) of oxygen and the arterial (a) concentration of oxygen

59

when is the alveolar-arterial gradient used?

in diagnosing the source of hypoxemia

-helps isolate the location of the problem as either intrapulmonary (within lungs) or extra pulmonary (somewhere else in body)

60

An abnormally increase A-a gradient suggest a defect in

-diffusion
-V/Q (ventilation/perfusion ratio) mismatch
- or right-to left shunt

61

what is hypoxemia

low concentration of O2 in the blood

62

what is oxygenation

the process where oxygen enters the bloodstream via the lungs

63

adequate oxygenation of the blood depends on many factors such as...

-atmospheric pressure (Patm)
-fraction of oxygen in inspired air (FiO2)
-movement of oxygen into the lungs (ventilation)
-adequate blood flow in the pulmonary capillaries (perfusion)
-oxygenated alveoli that are perfused with blood (ventilation-perfusion matching)
-movement of oxygen across the alveolar-capillary membrane (diffusion)

64

any problems with one or more of these factors will cause inadequate oxygenation of the blood and would be reflected as

low arterial oxygen partial pressure
low O2 which is hypoxemia

65

hypoxemia is caused when

there is not enough oxygen getting into the alveoli
-not enough oxygen transferred into the capillary blood

66

what is the alveolar-arterial oxygen gradient (A-a gradient)

difference (gradient) between alveolar oxygen pressure and arterial oxygen pressure

67

the 5 main mechanisms of hypoxemia fall under what 2 main categories

1. not enough oxygen getting into the alveoli (will have normal A-a)
2. not enough oxygen transferred into the capillary blood (will have elevated A-a)

68

what 2 main mechanisms of hypoxemia fall under the category of not enough oxygen getting into the alveoli

1. low atmospheric pressure ex: high altitude
2. hypoventilation ex: heroin overdose

69

what 3 main mechanisms of hypoxemia fall under the category of not enough oxygen transferred into the capillary bed

1. ventilation-perfusion mismatch ex: atelectasis
2. right-to-left shunting ex: atrial septal defect
3. diffusion defects ex: pneumonia

70

what is the equation for A-a gradient

A-a gradient = PAO2 - PaO2

71

what is the expected normal A-a gradient

< (age/4) +4

72

how to calculate the A-a gradient

use the alveolar gas equation and values from the arterial blood gas

step 1: calculate PAO2 (at sea level)
PAO2 = (Patm-Pwater) FiO2 - PaCO2/.8
step2: calculate A-agradient: PAO2-PaO2
step 3: compare expected A-a to calculated A-a v

73

what pH is acidic

under 7.35

74

what pH is basic

over 7.45

75

what PaCO2 is acidic

greater than 45

76

what PaCO2 is basic

less than 35

77

what bicarb is acidic

less than 22

78

what bicarb is basic

greater than 26

79

respiratory acidosis is

low pH, high PaCO2, normal bicarb

80

what is respiratory alkalosis

high pH, low PaCO2, normal bicarb

81

what is metabolic acidosis (simple)

low pH, normal PaCO2, and low bicarb

82

what is metabolic alkalosis (simple)

high pH, normal PaCO2, and high bicarb

83

Repiratory processes alter the blood pH by changing the

carbon dioxide levels

84

what is the main way the human body eliminates acid and maintains acid-base homeostasis

CO2 elimination via the lungs

85

what is respiratory acidosis (explanation)

when CO2 accumulates in the blood (elevated PaCO2) like when a person hypo ventilates, acid builds up and the pH decreases

86

what is respiratory alkalosis (explanation)

increase CO2 elimination (low PaCO2) like when a person hyperventilates, the amount of acid in the blood decreases and the pH increases

87

in the following ABG, is there. respiratory acidosis or respiratory alkalosis?

ABG: 7.32/50/98
99% O2 saturation on room air

alkalosis

88

what is external respiration

the exchange of gas (CO2 and O2) between the lungs (alveoli) and blood (pulmonary capillaries)

89

gas exchange occurs down a pressure gradient via ____ across the ____ _____

via diffusion

across the respiratory membrane

90

gases move from an area of

high concentration (high pressure) to low concentration (low pressure)

91

factors affecting rate of gas diffusion

1. thickness of membrane
2. surface area of membrane
3. diffusion coefficient of gas in membrane
4. partial pressure (concentration) difference of gas on either side of membrane

92

CO2 diffuses ___ more rapidly than O2

20x

93

laws that govern gas exchange

Boyles
Charles
ideal gas
henry

94

Boyles law

at constant temperature, pressure and volume vary inversely

P1 x V1 = P2 x V2

95

Charles law

movement of gases is dependent on temperature
temperature and volume vary directly

V/T = k

96

ideal gas law (dalton's)

each gas in a mixture will exert its own pressure depending on the # of moles present and the temperature and volume of the mixture

PV = nRT

97

henry's law

the absolute concentration of a gas dissolved in a liquid is dependent on the solubility coefficient of that gas in that liquid

98

during quiet inspiration, what happens to the volume and pressure

lung volume increases
pressure in lungs decrease
thoracic pressure decreases (5 mmHg below atmospheric pressure)

99

what is the basic thing to remember about Charle's law of gases

gases tend to expand when heated

100

Dalton's law of partial pressures tells us that

the total pressure in a mixture of gas is the sum of the partial pressures of each gas

101

the solubility of a gas in any solvent is ____ as the pressure over the solvent increase

the solubility of a gas in any solvent is increased as the pressure over the solvent increases

102

the solubility of the gas increases in direct promotion to what

its partial pressure above the solution

103

the solubility of gases in water ____ with increasing temperatures

decreases with increasing temperatures

104

what pressure in the lung can influence the distribution of blood flow and vascular resistance?

vascular segments (arteries, capillaries, and veins)

extravascular pressures (intrathroacic or intrapleural)

transmural pressure

105

mean hydrostatic pressure in the arteries

pulmonary: 13-19
systemic: 90

106

mean hydrostatic pressure in capillaries

pulmonary: 10
systemic: 30

107

mean hydrostatic pressure in veins

pulmonary: 5
systemic: 10

108

mean hydrostatic pressure in atria

pulmonary: 4
systemic: 2

109

intravascular hydrostatic pressure refers to

the actual pressure inside pulmonary vessels relative to atmospheric pressure

110

the pressure drop b/w pulmonary artery and capillary is small compared to systemic vessels bc

the lung lacks high resistance arterioles

111

the lack of arterioles in the lungs minimizes what

active regulation of lung blood flow distribution

112

intravascular driving pressure for pulmonary circulation

the difference b/w inflow and outflow pressures

difference b/w pulmonary arterial (Pa) and left atrial pressure (Pla)

113

the normal mean driving pressure is about

11 mmHg

114

in the pulmonary circulation, a small driving pressure is adequate because

of the relatively low resistance to blood flow

115

what does transmural pressure refer to

the pressure difference between the inside and outside of some walled structure

116

because airway and blood vessels walls are distensible, pressure differences between the inside and outside can affect....

their diameter, therefore the resistance they offer to air or blood flow

117

what is intrathoracic pressure

the pressure immediately outside large lung vessels

118

during quiet breathing, intrathoracic pressure is less than

atmospheric pressure and becomes increasingly subatmospheric with inspiration

119

large vessels and airways tend to passively dilate with...

inspiration as the outside intrathoracic pressure decreases

120

these larger lung vessels, whose outside pressure is intrathoracic are referred to as

extra alveolar vessels

121

the pressure immediately outside the lung capillaries is

alveolar pressure

122

how does alveolar pressure affect alveolar vessels

the diameter and resistance to blood flow offered by these

123

when alveolar pressure is increased, what does it do to the lung capillary and flow

narrow (squeeze) the lung capillary and increase resistance to flow

124

the transmural pressure differences in alveolar vessels can also affect

resistance to blood flow
intravascular pressures
blood flow distribution

125

what is surfactant

phospholipid that reduces the surface tension of water and is secreted and lines the interior surface of the alveoli

126

surfactant decreases surface tension most at ____ and least at ____

most at low volumes and least at high volumes

127

surfactant makes surface tension in the alveoli vary with

lung volume

128

what is surface tension and what does it cause

cohesive force b/w liquid molecules

causes the inward collapse (recoil) of the alveoli

129

LaPlace law

P = 2T/rP

pressure required to keep alveolus open

130

small alveoli have higher ___ ____ and are harder to keep open

collapsing pressure

131

a decrease in alveolar surface tension by surfactant causes a decrease in....

collapsing pressure in alveolus

132

surfactant increases lung compliance which in turn decreases....

the work of expanding lungs during inspiration

133

neonatal respiratory distress syndrome is caused by

a deficiency or absence of surfactant

134

how does neonatal RDS affect V/Q

decreases V/Q

collapsed alveoli are not ventilated and do no participate in gas exchange which results in hypoxemia

135

additional important lung products

- prostaglandins
-histamine
-kallikrein
-inactive kininogens
-angiotensin-converting enzyme (ACE)

136

what does histamine do

binds receptors on smooth muscle cells induce vasodilation, bronchoconstriction

137

what does kallikrein do

catalyzes proteolytic cleavage of kininogens in kinin synthesis

138

ACE inactivates

bradykinin

139

ACE inhibitors increase...

bradykinin which leads to cough, angioedema

140

the upright human lungs measures about ____ from the apex to the base

30 cm

141

the pulmonary artery enters the lung at the level of the

hilum
about midway between the apex and base of the lung

142

in order for the right heart to pump blood to the apex of the lung, what must it pump against

a column of blood about 15 cm high or against a pressure head of about 15 cm H2O resulting from gravity

143

because the right heart has a lot to push against, the mean intravascular pressure at the lung apex is

11 cm H2O lower than arterial pressure at the hilum

144

mean intravascular pressure at the BASE of the lung is about

11 cm H2O higher than pulmonary arterial pressure at the hilum

145

due to gravitational forces, both intravascular pressures and blood flow are considerably ____ at the apex than at the base of the lung

less at the apex than at the base of the lung

146

when a person assumes a supine position, the pressure differences b/w the apex and base are ____, therefore results in more uniform distribution of blood flow and smaller vascular pressure differences

differences b/w the apex and base are less

147

alveolar pressure may be above atmospheric pressure in briefly during (2)

1. forced expiration
2. chronically during positive pressure breathing

148

at a given blood flow, ____ in alveolar pressure are generally reflected by nearly equivalent increases in pulmonary arterial pressure up to about 8 cm H2O

increases

149

what is alveolar hypoxia

when the airway or alveolar PO2 is lower than normal

150

what is hypoxic pulmonary vasoconstriction

constriction of the arterial vessels leading to them

-redirects blood flow away from poorly oxygenated alveoli towards alveoli that have higher PO2 levels

151

HPV is a mechanism that normally operates to help optimize or improve...

gas exchange by decreasing blood flow to poorly oxygenated alveoli

152

pulmonary shunting is

portion of the cardiac output that moves from the right to the left side of the heart w/o being exposed to alveolar oxygen (blood flow with no O2) perfusion with out ventilation

V/Q = 0
always pathological

153

normal anatomic shunt

2-3% of cardiac output

(thebesian veins, pleural and bronchial blood flow)

154

abnormal anatomic cardiac shunt

ASD, VSD, TOF, DORV (double outlet right ventricle)

155

pulmonary shunt leads to

hypoxemia as alveoli collapse or fill with fluid or exudate (atelectasis, pulmonary edema, pneumonia)

156

major difference b/w shunt and V/Q mismatch

V/Q mismatch responds to oxygen therapy

shunt is refractory and doesn't respond easily

157

true shunt are

autonomic shunts and capillary shunts

158

intrapulmonary shunting is

blood flow through pulmonary capillaries w/o participating in gas exchange

159

anatomic shunt exists when

blood passes through an anatomic channel of the heart and does not pass through the lungs

caused by: congenital heart disease, intrapulmonary fistula, vascular lung tumors

160

capillary shunts are commonly caused by

alveolar collapse or atelectasis, alveolar fluid accumulation or alveolar consolidation

161

capillary + anatomic shunt =

absolute or true shunt

does not respond well to O2 therapy bc alveolar oxygen does not meet the shunted blood

162

relative shunt

pulmonary capillary perfusion is in excess of alveolar ventilation

163

venous admixture

end result of pulmonary shunting
mixing of shunted, non-deoxygenated blood with deoxygenated blood

164

ventilation perfusion ratio

V/Q
the relationship of the overall alveolar ventilation to the overall pulmonary blood flow

normal: 4:5 or 0.8-1

165

patients with shunts are more ____ than those with VQ mismatch and they may require ___ _____

hypoxemia than those with VQ mismatch and they may require mechanical ventilators

166

Zone 1 of the lung

vessels are compressed and there is no blood flow but you get oxygenation
Palv > Pa > Pv

167

zone 2 of the lung

"vascular waterall": the flow is independent of the eventual venous pressure and depends only on the difference b/w pulmonary arterial pressure and alveolar pressure
Pa > P alv > Pv = flow occurs but with resistance

168

Zone 3 of the lung

the venous pressure is greater than the alveolar pressure so that flow depends on the arteriovenous pressure difference
Pa > Pv > Palv = capillary dilation = less resistance = more flow

169

conditions that cause an entire lung to convert to zone 1

1. blood loss (hemorrhage) hypovolemia
2. positive pressure ventilation

170

the bulk of the lung in most normal healthy people and in most postures is represented by what zone

2

171

which zone has the highest blood flow

zone 3

172

in patients, how can pulmonary vascular resistance be obtained?

by using a Swan-Ganz or pulmonary artery catheter

173

where is the Swan-Ganz and catheter inserted?

inserted into a systemic vein (ex: jugular) and advanced through the right heart into the pulmonary artery

174

what does the Swan-Ganz and catheter directly measure?

-used to measure pulmonary arterial (Pa) and estimate left atrial pressure (Pla) and determine blood flow (ex: CO)
-can therefore compute PVR

175

how much of the total PVR resides in the capillaries

50-60%

176

PVR is ____ of SVR bc

1/10 of SVR b/c low pressure system

177

important to recognize that the distribution of PVR likely varies with changes in

blood flow, left atrial pressure, alveolar pressure and body position

178

whenever blood flow to the lung or left atrial pressure is increase, what happens to the calculated PVR

decreases

179

PVR declines with increase in blood flow and is accounted for by

capillary recruitment and distension

180

when blood flow or Pla is increase, previously closed capillaries are ___ and patent capillaries are further distended

recruited (opened)

181

With more and wider parallel channels (capillaries) available for flow, what happens to the flow and resistance

calculated resistance to flow declines bc resistances arranged in parallel

182

Lung inflation affects PVR because of the influence of

intrathoracic pressure and alveolar size upon extra-alveolar and alveolar vessels

183

intrapleural (intrathoracic) pressure becomes more sub atmospheric during ____ which increases transmural pressure to ______

inspiration

which increases transmural pressure to passively dilate extra-alveolar vessels

184

flow resistance in these vessels diminish as

lung volume increases

185

As lung volume is increased from residual volume (RV) to total lung capacity (TLC), what happens to vascular resistance

steadily declines in extra-alveolar vessels

186

as alveoli expand to larger volumes, they to do what to alveolar vessels

tend to compress and narrow alveolar vessels

187

when is PVR typicaly lowest or at, or close to

FRC (function residual capacity) or normal resting end-expiration

188

what is hematocrit

percentage of the total blood that is occupied by red cells

189

an increase in the number of red cells (increased hematocrit) increases the viscosity of red cells and therefore calculated PVR is also

increased

190

increase PVR (7)

sympathetic innervation
a-Adrenergic agonist
thromboxane/PGE2
endothelin-1
angiotension
histamine
alveolar hypoxemia

191

decrease PVR (7)

parasympathetic innervation
acetylcholine
B-adrenergic agents
PGE1
prostacyclin
nitric oxide
bradykinin

192

adult lung has about how much alveoli

300 million alveoli each surrounded by a capillary mesh

193

gas exchange is optimal in alveoli where

the fraction of alveolar ventilation (V) is matched to the fraction of cardiac output (Q) perfusing that alveolus

194

some alveoli may be over ventilated relative to their blood flow and exhibit a V/Q of

over 1.0

195

other alveoli may be over-pursued relative to their ventilation and have a V/Q of

<0.8

196

at extremes, some alveoli may be ventilated but received no perfusion, so V/Q is

infinite V/Q

197

alveoli may be perfused but not ventilated which makes the V/Q

very low V/Q

198

V/Q match

local mechanisms adjust for poor air flow and/or poor blood flow

199

Pulmonary arterioles have receptors that sense

H+ concentrations and low O2 (chemoreceptors)

200

Fick's law of diffusion: diffusion is proportional to

partial pressure difference (gradient) and surface area

201

Fick's law of diffusion is inversely proportional to

membrane thickness and diffusion distance

202

hemoglobin contains

4 heme molecules and 1 globing molecule

203

each heme molecule can carry

4 O2 molecules

204

1mg hemoglobin can carry

1.34 ml of O2

205

internal respiration occurs as

simple diffusion

206

carbon dioxide diffuses out of the __ and goes where

diffuses out of the tissue, cross the interstitial fluid and enter the blood

-then carried back to the lungs either bound to hemoglobin, dissolved in plasma, or in a converted form

207

oxygen delivery is a function of

arterial oxygen content and cardiac output

208

oxygen consumption

is the rate at which tissues take up oxygen and is a function of oxygen delivery and amount of oxygen that is extracted by tissues

209

Hgb is 50% saturated at a plasma PO2 of approx

27 mmHg

210

Normal venous blood has PvO2 at ___ and oxyhemoglobin sat at ___

40 mmHg

sat of 75%

211

normal arterial blood has PaO2 of ___ and oxyhemoglobin sat of

97 mmHg

sat of 97%

212

Haldane effect

PO2 affects the ability of the blood to carry CO2

213

Bohr effect

a decrease in pH shifts the curve to the right

incr pCO2, incr temp, incr DPG

214

an increased P50 causes a

decreased affinity of Hb to O2

215

lower P50 indicates a

leftward shift and a higher affinity of Hb to O2

216

fetal hemoglobin has a

higher affinity for oxygen

causes a leftward shift and lower P50

217

methemoglobinaemia

Fe3+
leftward shift = lower P50

218

carbon monoxides binds to hemoglobin ___ times more readily than with oxygen

240 times

shifts curve to the left

219

with an increased level of carbon monoxide, a person can suffer from

severe hypoxemia while maintaining a normal PO2

220

anemia in terms of blood O2/PO2 curve

increase in 2,3-DPG shifts curve to the right

-decreased affinity for O2 translates to better O2 offloading to tissues

221

acute high altitude

thin air, causes hyperventilation
decreases PCO2 and increase pH shifts curve to the left

222

acclimation to high altitude

polycythemia occurs
increases 2,3 DPG and shifts curve to the right

223

factors that increase C(a-v)O2 and decrease SvO2

-decreased CO
-exercise
-hyperthermia
-seizures
-shivering in post-op patient

224

factors that decrease the C(a-v)O2 and increase SvO2

-increased CO
-skeletal muscle relaxation
-peripheral shunting
-certain poisons
-hypothermia

225

when the C(a-v)O2 increases....

the SvO2 decreases

226

three main forms of CO2 transport in blood

1. as bicarbonate ions (70%)
2. as carbamino-hemoglobin (15-25%)
3. dissolved in plasma (5%)

227

where are three influences on control of respiration

1. chemical influences of the respiratory center of the brain neural influences
2. cortical influences voluntary controls in the medullary rhythmicity center and pontine respiratory center neurons limit inspiratory
3. proprioceptive stretch receptors in the lungs

228

how does the medullary rhythmicity center control respiration

autorythmic inspiratory and expiratory neurons sets the basal ventilation

229

how does the pontine respiratory center neurons limit inspiratory

impulses causing shorter cycles which increases ventilation rate

230

the respiratory center of the brain is controlled by a

negative feedback pathway

231

Increased pO2, decreased pCO2, and a drop in H+ all interact to

discourage ventilation to retain more CO2

232

decreased pO2, increased pCO2, and a rise in H+ all interact to

encourage ventilation to blow off more CO2

233

central chemoreceptors control ___% of the responses

70%

medulla

234

peripheral chemoreceptors control ___% of responses

30%

carotid and aortic bodies

235

Pulmonary arteries have thin walls and are under lower pressure. what does this create?

lower hydrostatic pressure gradients
this minimizes the tendency for fluid to filter out of the pulmonary capillaries into the airspaces

236

hydrostatic pressure

tends to push fluid out of vessels

237

colloid oncotic pressure tends to

pull fluid into vessels

238

what are the causes of pulmonary edema

1. high pressure
2. low pressure

239

high pressure edema

-hydrostatic, cardiogenic
-common w left heart failure results in more fluid filtration from the vascular space than can be returned by plasma oncotic forces

-left atrial pressure threshold for pulmonary edema is about 25 mmHg

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low pressure edema

-high permeability, noncardiogenic
-results from an increase in permeability of the barrier that separates blood from the tissues

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what is neurogenic pulmonary edema

from head injury, SAH, intercebral hemorrhage

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cariogenic pulmonary edema comes from

heart failure and fluid overload (kidney and liver)

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noncardiogenic pulmonary edema comes from

lung and capillary

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5 causes from pulmonary edema in relation to starling forces

1. increased hydrostatic pressure
2. reduced oncotic pressure
3. reduced lymphatic drainage
4. increased surface tension
5. increased capillary permeability

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starling forces favor movement of fluid from

inside capillaries to the interstitial space

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what is obstructive lung disease

-have SOB due to difficulty exhaling all the air from the lungs.
-exhaled air comes out more slowly than normal

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what are types of obstructive lung disease

1. COPD
2. asthma
3. bronchiectasis
4. cystic fibrosis

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what is restrictive lung disease

cannot fully fill their lungs with air

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types of restrictive Lung disease

1. interstitial lung disease
2. sarcoidosis
3. obesity
4. scoliosis
neuromuscular disease

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in an oxygenator, gas transfer from the

gas to the liquid phase

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what is gas transfer driven by in an oxygenator

diffusion according to the partial pressure difference of the particular gas

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the region in which variation in velocity occurs is defined as

boundary layer

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blood or any other viscous fluid flowing past either a stationary surface or a bubble will have variations in velocity from

zero at the interface surface to that of the free stream

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the major resistance to gas diffusion occurs in the

blood phase

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efforts to improve gas exchange

1. increase welling times
2. increasing driving gradient
3. decreasing the diffusion path by making the surface of the membrane irregular or positioning the elements within the flow stream to disrupt the smooth flow

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an eddy current has an impact on the

boundary layer of the fiber, disrupting its development and reducing its thickness