Term
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Definition
| normal atmospheric inspired partial pressure of oxygen (Pio2) of 159 mm Hg to a low point of 40 mm Hg or less in the capillaries. The intracellular Po2 (approximately 5 mm Hg) provides the final gradient for oxygen diffusion into the cell. |
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Term
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Definition
partial pressure of carbon dioxide (Pco2) is highest in cells (approx. 60 mm Hg) and lowest in room air (1 mm Hg)
alveolar partial pressure of carbon dioxide, or PAco2, varies directly with body's production of carbon dioxide and inversely with alveolar ventilation |
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Term
| RULE OF THUMB - Oxygen/CO2 Content |
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Definition
if patient breathing room air, sum of alveolar Po2 (PAo2) and alveolar Pco2 (PAco2) = about 140 mm Hg (100 mm Hg and 40 mm Hg).
Changes in ventilation that cause PAco2 to vary will vary the resulting PAo2 to keep total at 140 mm Hg. |
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Term
| whenever a patient is breathing room air at sea level, the RT should not expect to see a PAo2 any higher than _______ during hyperventilation. Po2 values higher than _______ indicate that the patient is breathing supplemental oxygen. |
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Definition
120 mm Hg , 120 mm Hg
For carbon dioxide or oxygen to move between the alveoli and the pulmonary capillary blood, the following three barriers must be penetrated: (1) alveolar epithelium, (2) interstitial space, and (3) capillary endothelium |
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Term
barriers to CO2/O2
between alveoli & pulmonary capillary blood |
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Definition
- alveolar epithelium
- interstitial space
- capillary endothelium
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Term
| to pass into and out of RBCs, gases must traverse the __________________ |
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Definition
| erythrocyte membrane (red blood cells) |
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Term
| Carbon dioxide diffuses approx. _______ across alveolar-capillary membrane than does oxygen, because of its _______________. |
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Definition
20 times faster
much higher solubility in plasma |
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Term
| The diffusion time in the lung depends on _________ |
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Definition
| the rate of pulmonary blood flow |
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Term
| blood normally takes approx. ________ to pass through pulmonary capillary |
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Definition
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Term
| If blood flow ______, i.e. during heavy exercise, capillary transit time can _____ to as ____ as ______ |
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Definition
increases
decrease
low
0.25 seconds |
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Term
| arterial blood reflects ___________ |
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Definition
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Term
| venous blood reflects _________ |
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Definition
| events occurring in the tissues |
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Term
| Pao2 of healthy individuals breathing air at sea level ______ alveolar Po2 of 100 mm Hg, but is approx. _________ than the calculated Pao2. |
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Definition
does not equal
5 to 10 mm Hg less |
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Term
| right-to-left anatomical shunts |
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Definition
-
bronchial venous drainage
-
thebesian venous drainage
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Term
| A high V/Q ratio indicates that ventilation is _________, perfusion is ________________. |
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Definition
greater than normal
less than normal, or both |
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Term
| In areas with a high V/Q ratio, the Po2 is _____ and the Pco2 is _____ than normal. |
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Definition
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Term
| Conversely, a low V/Q indicates that |
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Definition
ventilation is less than normal
perfusion is greater than normal
or both |
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Term
| In areas with low V/Q, the alveolar Po2 is _____ and the Pco2 is _____ than normal. |
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Definition
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Term
| Farther down the lung, perfusion increases _____________________ so the lung bases receive _____________________ as do the apexes. |
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Definition
linearly in proportion to the hydrostatic pressure
nearly 20 times as much blood flow
(lungs have more blood at bottom than top due to gravity) |
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Term
| Like perfusion, ventilation also is increased in the lung bases, with ca. four times as much ventilation going to the bases than to the apexes of the upright lung |
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Definition
| Like perfusion, ventilation also is increased in the lung bases, with ca. four times as much ventilation going to the bases than to the apexes of the upright lung |
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Term
| Majority of oxygen is carried in... |
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Definition
| ...a reversible chemical combination with hemoglobin (Hb) inside the RBC |
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Term
| With complete oxygen binding, all electrons become ______, and _____ is converted to its ____ state (referred to as _______ and abbreviated ______). |
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Definition
paired
Hb
oxygenated
oxyhemoglobin
HbO2 |
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Term
| In whole blood, each gram of normal Hb can carry... |
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Definition
| approx. 1.34 ml of oxygen |
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Term
SaO2 = [HbO2÷ Total Hb] × 100
SaO2 = Hb saturation (Sao2) |
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Definition
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Term
with Po2 < 60 mmHg, curve steepens dramatically
CaO2 = (0.003 × PO2) + (Hbtot × 1.34 × SO2) |
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Definition
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Term
| Cao2 = Total oxygen content |
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Definition
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Term
| Po2=Partial pressure oxygen in blood = same here as PaO2 |
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Definition
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Term
| Hbtot = Total hemoblobin content (in g/dl) |
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Definition
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Term
| So2 = Hb sat. with oxygen (as decimal) = same here as SaO2 |
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Definition
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Term
Note: (0.003xPaO2) = amount dissolved in plasma
(Hb x 1.34 x SaO2) = amount bound to hemoglobin |
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Definition
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Term
| The normal Cao2 concentration is |
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Definition
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Term
| As we breathe in the water vapor pressure _______ |
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Definition
displaces some of the oxygen
This pressure gradient is called a cascade |
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Term
| Alveolar CO2 & arterial CO2 are |
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Definition
| nearly same in healthy adult |
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Term
| if CO2 production increases |
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Definition
| alveolar minute ventilation stays or decreases |
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Term
| Normal partial pressure of CO2 in alveoli is |
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Definition
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Term
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Definition
| partial pressure of inspired oxygen |
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Term
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Definition
PIO2 = FIO2 (PB - 47)
47 = Water Vapor Pressure |
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Term
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Definition
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Term
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Definition
PAO2 = FIO2(PB - 47) - 1.25(PACO2)
If FIO2 greater than 60%, drop the multiply by 1.25 part |
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Term
| PaO2 and PaCO2 relationship is |
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Definition
Inverse
if one increases, the other decreases and vice versa |
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Term
| Carbon Dioxide & Oxygen diffusion speeds across alveolar capillary membrane |
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Definition
| CO2 diffuses 20 times faster than oxygen, because it has hiher solubility in plasma |
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Term
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Definition
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Term
| normal speed of blood through capillary |
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Definition
0.75 sec
Can go as low as 0.25 |
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Term
| Effect of blood flow speed on diffusion |
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Definition
| If flows too fast diffusion cannot occur |
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Term
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Definition
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Term
| Once PAO2 (100 mmHg) hits circulation, what happens to PaO2? |
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Definition
| arterial O2 pressure can be 5 - 10 mmHg lower because of right to left shunts & regional differences |
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Term
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Definition
| a right to left side shortcut of the heart |
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Term
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Definition
- bronchial venous drainage
- thebesian venous drainage
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Term
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Definition
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Term
| Higher ventilation/perfusion ratio means |
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Definition
greater ventilation or lower bloodflow or both
(ideal is even between both) |
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Term
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Definition
| higher ventilation and lower perfusion |
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Term
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Definition
| Lower ventilation and higher perfusion |
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Term
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Definition
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Term
| How much oxygen can a gram of Hemoglobin hold? |
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Definition
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Term
| figure Saturation of arterial oxygen in percentages |
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Definition
| %SaO2 = [HbO2 / Total Hb] x 100 |
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