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282 Cards in this Set

  • Front
  • Back
What is the PO2 in the arteries?
100
What is the PCO2 in the arteries?
40
What is the PO2 in the veins?
40
What is the PCO2 in the veins?
46
What happens when the diaphragm contracts?
Inhalation; expanding the volume of the thorax
Where does gas exchange take place?
The alveolar ducts and alveoli
What is the alveolar wall?
An array of capillary segments
What cells make surfactant?
Alveloar type 2 cell; pneumocyte type 2
What is the total atmospheric pressure?
760 mmHg
How much of the total atmospheric pressure does O2 make up?
21%
How much of the total atmospheric pressure does N2 make up?
79%
What is the partial pressure of 02?
160 mmHg
What is the partial pressure of N2?
600 mmHg
What is the equation of a partial pressure of a gas?
Pgas=Fgas * Ptot
Does the partial pressure change in the airways? Why?
Yes; due to water vapor
What is the partial pressure of water vapor?
47 mmHg
What is the partial pressure of O2 and N2 in the airways?
713 mmHg
What is the partial pressure of O2 in the airways?
150 mmHg
What is the parial pressure of N2 in the airways?
563 mmHg
How do gases move?
Down a partial pressure gradient
What is the A-a difference?
The difference between the PAO2 and the PaO2
If the A-a dfference is large, what does this mean?
That it is a poor exchanger
What factors determine how much gas is exchanged by the system?
Area, thickness, solubility, concentration gradient, and degree of matching
What is the ideal exchanger?
When the ventilation and the perfusion are perfectly matched
If the ventilation and the perfusion are perfectly matched, what is the A-a difference?
Minimal
What happens when an airway is blocked?
There is no ventilation but there is perfusion
When there is no ventilation but there is perfusion, what is this called?
Right to left lung shunt
What does the shunt result in?
Lowering the partial pressure of O2 in the mixed blood leaving the lung
What happens when there is an embolus?
There is no perfusion but there is ventiation.
When there is no perfusion but there is ventilation, what is this called?
Dead space; wasted ventilation
What happens to the PAO2 and the PaO2 in dead space?
The PAO2 will be higher than normal and the PaO2 will be normal
What keeps the lungs inflated?
A negative pleural pressure of 7.5
What happens to the chest wall on inspiration?
The diaphragm is pulled up, the rib cage is pulled in, and the lung is inflated
What is the lung's elastic recoil force acting to do?
Collapse the lung
What is the chest wall's elastic recoil force acing to do?
Expand the chest wall
What is the functional residual capacity (FRC)?
When the elastic recoil forces of the lung and chest wall are equal and opposite; equiibrium
What is happening at FRC?
Your mouth is open and your respiratory muscles are all relaxed
What is the main contributor to lung recoil?
Surface tension
What is Laplace's Law?
P=T/R
What does surfactant do?
Lowers surface tension
If surfactant is not present, what happen?
Lung recoil forces are very high
Is surfactant more concentrated in a smaller lung or bigger lung?
Smaller lung
Is surfactant hydrophobic or hydrophilic?
Hydorphobic
What keeps the pressure the same in lungs of different sizes?
Surfactant
What does surfactant do to compliance?
Lowers compliance
Where does the recoil force come from?
Tissue elastic recoil forces and surface tension forces
Is inhalation an active or passive process?
Active process
Is exhalation an active or passive process?
Passive process
Is forced exhalation and avtive or passive process?
Active process
What is the pressure in the alveoli at FRC?
Zero
What is the alveoli pressure during inspiration?
Negative
What is the alveoli pressure at the end of inspiration beginning of exhalation?
Zero
What is the alveoli pressure during expiration?
Positive
What is the alveoli pressure at the end of the respiratory cycle?
Zero
What is the pleural pressure at FRC?
Negative
What is the pleural pressure during inspiration?
More negative
What is the pleural pressure at the end of inspiration beginning of expiration?
More more negative
What is the plueral pressure during expiration?
Less negative (than during expiration)
What is the pleural pressure at the end of the respiratory cycle?
Negative
What kind of pleural pressure does forced exhalation give?
Positive
What holds the lung expanded during normal breathing?
Negatvie pleural pressure
In the pressure-volume graph, what does slope measure?
Compliance
What is a cheap and easy way to measure lung compliance?
Spirometer
What does the spirometer measure in order to tell us lung compliance?
Relaxation pressures
What does fibrosis due to lung compliance?
Lowers it because it makes it harder to inflate
If surfactant is lost, what happens to lung compliance?
It is lowered
What does emphysema do to lung compliance?
It raises lung compliance becuase of the loss of elastic fibers; lung is easier to inflate
What are the pleural and alveoar pressures during forced expiration?
Both are positive
What happens to the airways during forced exhalation?
They collapse
What expels gas in a noraml passive exhalation?
Lung elastic recoil force
What does less recoil force mean?
Less airflow
What kind of exhalation are emphysema patients using?
Forced exhalation
What happens to the side wall pressure when gases are flowing fast?
It decreases
What happens to airways when the flow is fast?
They collapse
Where is flow rate the greastest?
In the large airways
What promotes stability of airways or alveoli?
Tethering--interconnections attaching aveoli to their neighbors
What are 2 factos that can keep airways open?
"Pursed-lip" breathing and PEEP
What does pursed lip breathing do?
Keeps a higher pressure along the airway to prevent collapse
Where is pleural pressure the most negative?
The uppermost part of the thorax
Where is pleural pressure the least negative?
The lowermost part of the thorax
What is repsonsible for the distribution of ventilation?
Gravity
During inhalation, do alveoli at the top of the lung or at the bottom of the lung have the greatest voume change?
The alveoli at the bottom of the lung
Which part of the lung is the most ventilated?
The bottom part of the lung
What is the single most valuable pulmonaty function test you can do?
Spirometer
What is FEV?
Forced expiratory volume in 1 sec
What is FEV an estimate of?
Airway resistance
The larger the FEV.....
The lower the resistance is
The smaller the FEV.....
The higher the resistance is--indicative of disease
What happens to the volume-flow loop in emphysema?
It is shifted to the left--concave curve
What happens to the volume-flow loop in asthma?
Limits flow but does not affect volume; shorter
What happens to the volume-flow loop in fibrosis?
The loop is shifted to the right; smaller volumes; no affect on flow rates
What is the residual volume?
The amount of gas left behind after a maximal exhalation
What is the tidal volume?
The amount of gas inhaled or exhaled during normal breathing
What is the FRC?
The volume remaining in the lung after normal relaxed exhalation
What happens to the volume-flow loop in fibrosis?
The loop is shifted to the right; smaller volumes; no affect on flow rates
What the the vital capacity?
The volume of gas expired when you for from full inhalation to a maximum exhalation
What is the residual volume?
The amount of gas left behind after a maximal exhalation
What is the tidal volume?
The amount of gas inhaled or exhaled during normal breathing
What is total lung capacity?
Total amount of gas in the lungs after maximal inhalation
What is the FRC?
The volume remaining in the lung after normal relaxed exhalation
What do you measure with a standard spirometer?
FEV
What the the vital capacity?
The volume of gas expired when you for from full inhalation to a maximum exhalation
What do you measure with a helium spirometer?
FRC
What is total lung capacity?
Total amount of gas in the lungs after maximal inhalation
What is the main respiratory muscle?
Diaphragm
What do you measure with a standard spirometer?
FEV
What do you measure with a helium spirometer?
FRC
What is the main respiratory muscle?
Diaphragm
How much air do we pump into alveoli every minute?
3600 ml
How much O2 is extracted per minute from the gas in the alveoli?
250 ml
How much CO2 do we put into the aveoli per minute?
200 ml
After gas exchange, how much O2 do the alveoli contain?
506 ml
After gas exchange, how much CO2 do the alveoli contain?
200 ml
After gas exchange, how much N2 do the aleveoli contain?
2844 ml
What is the mole fraction of O2 after gas exchange?
0.142
What is the mole fraction of CO2 after gas exchange?
0.056
What is the mole fraction of N2 after gas exchange?
0,801
How many total ml's of gas do the alveoli contain after gas exchange?
3550 ml
What is the equation for tidal ventilation?
Vt * f = Vd * f + Va * f; f=frequency of breaths per minute
What is Va?
Ventilation of exchanging areas
What is Vd?
Ventilation of dead space
What is the alveolar gas equation 1?
PaCO2~VCO2/Va
In the alveolar gas equation 1, what happens if you double the Va?
Halve the PaCO2
In the alveolar gas equation 1, what happens to the VCO2 if you double the PaCO2?
Double the VCO2
What happens to PaCO2 during hyperventilation?
The PaCO2 is halved
What happens to the PaCO2 during hypoventilation?
The PaCO2 is doubled
What is the PaCO2 set by?
The rate of ventilation and the rate of CO2 production
What is the alveolar gas equation 2?
PAO2 = PiO2 - PaCO2 / R
What happens to PAO2 during hyperventilation?
Raised PAO2
What happens to PAO2 during hypoventilation?
Lowers PAO2
What happens to PAO2 during high altitude?
Lowers PAO2
What are the two types of dead space?
Anatomical dead space and physiological dead space
Where is anatomical dead space?
The large airways
Where is physiological dead space?
Alveoli that are venitlated but are not perfused
When we measure dead space, are we measuring physiological or anatomical dead space?
Physiological dead space
Where is O2 transported?
From the lungs to the tissues
Where is CO2 transported?
From the tissues to the lungs
In metabolizing organs, what happens to O2 and CO2?
O2 is consumed and CO2 is produced
What is the amount of O2 dissolved in blood a funtion of?
The partial pressure of the gas and the solubility of the gas in the liquid
For blood in the lungs, where PO2 is 100, the amount of O2 dissolved is?
O.3 ml/dl
What two forms is O2 carried in?
Dissolved in the plasma and bound to hemoglobin
Is O2 poorly or greatly soluble in water?
Poorly soluble in water
What does hemoglobin do for O2?
Serves as a buffer
How is O2 tranported throughout the blood?
Hemoglobin
How is the vast majority of hemoglobin carried in the blood?
Bound to hemoglobin
How does O2 move in and out of blood?
Through the dissolved compartmet
What is the total amount of hemoglobin in the blood equal to?
The amount dissolved plus the amount bound to hemoglobin
How is CO2 transported in the blood?
Dissolved in plasma, as bicarbonate, and bound to hemoglobin
How is most CO2 transported?
In the form of bicarbonate
Is CO2 poorly or highly soluble in water?
Highly soluble in water
In the RBC, the reaction of CO2 and water is catalyzed by what?
Carbonic anhydrase
Does CO2 show saturation kinetics on a graph?
No
Can deoxygenated hemoglobin carry more or less CO2 as carbamino?
Can carry more CO2
What type of curve is the relationship between PCO2 and CO2?
Linear--no saturation kinetics
Can you average the PO2's from two different samples?
No, you have to average the O2 content of the samples to see what the resulting PO2 of the sample is
Can you average the PCO2's from two different samples?
Yes, because it is a linear relationship
What is P50?
The PO2 at which hemoglobin is 50% saturated with O2
What are 3 things that lower the affinity for O2?
H+ ion concentation, temperature, and PCO2
In tissues, is H+ concentration high or low?
High
In tissues, is temperature high or low?
High
In tissues, is HbCO2 high or low?
High
When H+, temperature, and HbCO2 are all high, what happens to the O2 saturation curve?
It shifts to the right because the affinity is lowered
What does lowering the affinity for O2 mean?
Favors the unloading of O2
In the lungs, is the H+ concentration high or low?
Low
In the lungs, is the temperature high or low?
Low
In the lungs, is the HbCO2 low or high?
Low
What does the H+ concentration, temperature, and HbCO2 all being low do to the O2 saturation curve?
It shifts it to the left because of increased affinity
What does a high affinity for O2 mean?
It favors loading of O2 and unloading of CO2
In the alveolar capillaries, is O2 loaded or unloaded into blood?
Loaded into blood
In the alveolar capillaries, is CO2 loaded or unloaded into blood?
Unloaded from blood
In the tissue capillaries, is O2 loaded or unloaded from the blood?
Unloaded
In the tissue capillaries is CO2 loaded or unloaded into the blood?
Loaded
In alveolar capillaries, what is the H+ concentration and temperature?
Both are low
In the tissue capillaries, what is the H+ concentration and temperature?
Both are high
What is the cooperative effect?
When one gas is removed from the blood, it enhances the uptake of the other
In the lungs, the removal of CO2 does what to the O2 concentration?
It promotes the uptake of O2 which raises the affinity
What does 2,3 DPG do to O2 affinity and which way does it shift the curve?
It lowers O2 affinity shifting the curve to the right
What does hypoxia do to 2,3 DPG?
Increases the level of 2,3 DPG
What is a good way to estimate the PO2 inside an organ?
Measure the PO2 in the venous blood from that organ
What volume % of O2 does arterial blood contain?
20 vol %
What vol % of O2 does venous blood contain?
15 vol %
What is the normal PVO2?
40
What is the Hb-O2 curve for anemia compared to a normal curve?
Lower than normal
What does CO do to the O2 saturation curve?
It shifts it to the left---increases the affinity for O2
How is the amount of O2 that is taken up from the blood determined?
By the rate of perfusion of pulmonary capillaries
Is O2 perfusion or diffusion limited?
Pefusion limited
Is CO2 perfusion or diffusion limited?
Diffusion limited
What does the pulse oximeter tell us?
The saturation of hemoglobing ONLY!
What is the affinity of hemoglobin regulated by?
2,3 DPG
Does fetal hemoglobin have a high or low affinity for O2?
High affinity
What are the two variables regulated in the respiratory system?
H+ in the blood and H+ in the brain interstitium
Is the blood PO2 subject to control?
Only if the PO2 is dangerously low
What are the 2 sets of chemsensors?
The carotid bodies and the central sensor that is located in the brainstem
What are the carotid bodies detectors of?
Blood H+ and blood PO2
What are the central chemsosensors sensitive to?
The H+ in the brain interstitial fluid
What does the controller do?
Receives inputs from the chemosensors and regulates the activity of the respiratory muscles
What does the effector do?
Muscles that control ventilation; dipahragm and intercostal muscles
What do the sensors in the carotid bodies repspond to?
Blood H+, blood PCO2, and blood PO2 (only responds to PO2 when it is low)
When CO2/H+ increases in the brainstem, what do central chemoreceptors do?
Increased ventilation
Does CO2 move freely across the blood brain barrier?
Yes
What are the respiratory chemorecptors mainly driven by in the blood and brain interstitum?
H+ concentration
What does increasing the number of H+ ions in the blood do to ventilation?
It increased ventilation
What degree of hypoxia must be present for PO2 to increase ventilation?
Moderate to sever hypoxia
Does the response to hypoxia ever adapt?
No
What does the combination of high H+ and hypoxia do to respiratory drive?
Increases it
What does an increase in ventilation do to H+?
Lowers H+ causing respiratory alkalosis
What does a decrease in ventilation do to H+?
Increases H+ causing respiratory acidosis; will also cause hypoxemia and elevated CO2
What does fever do to ventilation?
Increased ventilation
What does mild hypothermia do to ventilation?
Increased ventilation
What does severe hypothermia do to ventilation?
Decreases ventilation
What does brain injury or drug overdose do to ventilation?
Depresses ventilation
What does painful stimuli do to ventilation?
Increases ventilation
What does panic do to ventilation?
Can result in hyperventilation
What are some drugs that reduce respiratory drive?
Alcohol
Opiates
Benzodiazepines
Barbituates
Anesthetics
What are some drugs that increase respiratory drive?
Cocaine
Amphetamine
Caffeine
Cyanide
What is Zone 1 in the lung?
Defined as the region that is not perfused and it at the apex of the lung
What is the arterial pressure in Zone 1?
Zero
What is Zone 2?
Region that is perfused but perfusion is independent of Pv
What is Zone 3?
Region where perfusion is determined by both Pa and Pv and is located at the base of the lung
Is the perfusion pressure constant in Zone 3?
Yes--8 cm H2O
Does the resistance to blood flow decrease or increase as you move to the bottom of the lung?
Resistane decreases
Where is perfusion of the lung smallest?
At the top of the lung
Where is perfusion of the lung the greatest?
At the base of the lung
What is one way to collect an alveolar gas sample?
Long slow exhalation
What is the A-a gradient a good measurement of?
Lung function or disease
When is gas exchange ideal?
When there is uniform distribution of V and Q
What does the number 0.8 represent?
A perfect match of V and Q
What does Q but no V represent?
Perfusion but no ventilation; shunt
What does V but no Q represent?
Ventilation but no perfusion; dead space
What part of the lungs receives the best perfusion and ventilation?
The bottom of the lungs
Does the bottom of the lungs have a high or low V/Q ratio?
Low ratio--meaning it is overperfused and acting somewhat shunt like
Does the top of the lungs have a high or low V/Q ratio?
High ration--meaning it is over ventilated acting somewhat like dead space
What is the V/Q ratio in the bottom of the lungs?
0.3
What is the V/Q ration in the top of the lungs?
3.o
Which part of the lung is overperfused and under ventilated?
The bottom
Which part of the lung is over ventilated and under perfused?
The top of the lung
What part of the lung acts like a shunt?
the bottom of the lung
What part of the lung acts like dead space?
The top of the lung
What does perfusion do to CO2?
Brings it into the lungs
What does ventilation do to CO2?
Takes it out
If the flow is large, what will the PCO2 be?
Large also.....the bigger the flow the higher the PCO2
Where there is V but no Q, what is PCO2?
Zero
Where there is Q but no V, what is PCO2?
Same as venous blood, 46
When the V/Q ratio is high, what is the PCO2?
Low
Ventilation does what to O2?
Brings it in
Perfusion does what to O2?
Takes it out
When there is V but no Q, what is O2?
Same as room air, 150
When there is Q but no V, what is O2?
Same as venous blood, 40
If Q is large, what is PO2?
Low
When the V/Q ratio is high, what is the PO2?
High
A lung unit with low V/Q ratio has what PCO2 and what PO2?
A low PO2 and a high PCO2
A lung unit with a high V/Q ratio has what PCO2 and what PO2?
A low PCO2 and a high PO2
What does a V/Q ratio of 0 represent?
Airway obstruction
What does a V/Q ratio of infinity represent?
Pulmonary embolus
Is the PO2 in the top of the lungs low or high?
High
Is the PCO2 in the top of the lungs high or low?
Low
Is the PO2 in the bottom of the lungs low or high?
Low
Is the PCO2 in the bottom of the lungs low or high?
High
If V is greater than Q, that means....
Over ventilated (top of the lungs)
If V is less than Q, that means......
Over perfused (bottom of the lungs)
What is a normal A-a gradient?
0.8 mmHg
What is the PaO2, A-a gradient, and PaCO2 in an umcompensated, low V/Q mismatch?
Low PaO2
Large A-a gradient
High PCO2
What are the compensation mechanisms for V/Q mismatches?
Hypoxia causes vascular smooth muscular contraction
Low PaCO2 causes bronchial smooth muscle contraction
Hypoxia and hypercapnia both increase ventilation
What does elevated PCO2 cause?
An increase in ventilation
What are some causes of low V/Q mismatches?
Emphysema
Bronichitis
Asthma
What is the normal A-a gradient?
8 mmHg
As we get older, what happens to our A-a gradient? Why?
It gets larger because of normal wear and tear on our lungs
What A-a gradient is suggestive of lung disease?
20 or more
What are the 5 causes of hypoxemia?
Breathing air w/ low PO2
Hypoventilation
Shunts
Low V/Q mismatch
Diffusion probelm
What is an example of breathing air w/ low PO2?
High altitude
What is the A-a gradient in a patient breathing air w/ low PO2?
Normal
What is an example of hypoventilation?
Brain damage, drugs
What is the A-a gradient in a pt that is hypoventilating?
Normal
What are the CO2 and O2 levels in a patient that is hypoventilating?
Hypercapnia and hypoxemia
What is the A-a gradient in a pt with a shunt?
Large
What is the A-a gradient in a pt with a low V/Q mismatch?
Large
What is an example of a patient with a low V/Q mismatch?
COPD
How do you tell the difference between a shunt and a low V/Q mismatch?
A person with a shunt will have minimal change in their PO2 when given 100% O2; a person with a low V/Q mismatch will respond very well to 100% O2
What are shunts caused by?
Filling your lungs with fluid, pus, vomit, or other liquids
What is a cause of a high V/Q ration?
Pulmonary embolus
If a person has poor response to administration of 100% O2, what do they have?
A R-L shunt
If a person responds very well to administration of 100% O2, what do they have?
A low V/Q mismatch