Final Exam Flashcards
Value of atmospheric O2?
160 mmHg
Value of inspired O2?
150 mmHg
Value of alveolar O2?
100 mmHg
Value of arterial O2 (PaO2)?
100 mmHg
What is the arterial CO2 (PaCO2)?
40 mmHg
Formula for compliance
C = delta V / delta P C= change in lung volume / change in pressure
Majority of total surface area of the lung is found in the
alveoli
all of the following can be measured via spirometry except:
- tidal volume
- vital capacity
- functional residual capacity
- inspiratory capacity
- expiratory reserve volume
functional residual capacity
how does the radii of the various tubes change as we move from the trachea to the alveoli?
Radii of the tubules decreases due to shedding of epithelial cells. Conducting zones (g0-16) columnar/cuboidal epithelia, smooth muscles, thick cartilage Respiratory zones (g17-23) type 1 and type 2 epithelia, No columnar/cuboidal epithelia, cartilage and smooth muscle = smaller radius
Pleural pressure = -7 cm H2O
Alveolar pressure = -3 cm H2O
Transpulmonary pressure = ?
+4 cm H20
A lung compliance test indicates that a 3cm H2O change in transpulmonary pressure generates a 0.9 L change in lung volume? What is the patient’s lung compliance?
0.3 L air/cm H2O
Airway resistance across a set of airways is lowest under which condition?
airway radius is large and the length of the tube is small
As the lungs fill with air and we move from a low lung volume to higher lung volumes, airway resistance will
decrease exponentially
What is the typical Tidal volume?
normal breathing = 0.5L
What is the typical expiratory reserve volume?
air expelled after normal tidal volume expiration = 2L
What is the residual volume?
air that remains after maximal expiration = 1.2 L
What is the forced vital capacity?
air which can be forcible exhaled from the lungs after taking the deepest breath possible = 5L
What is the vital capacity?
air that is exhaled after maximal inspiration = 5L
what is total lung capacity?
max volume the lungs can be expanded = 6L
What is the functional residual capacity?
Air left in lungs below tidal = 2.5L
What is the inspiratory reserve volume?
air that can be inhaled after tidal - 2.5L
What is the inspiratory capacity?
air that can be drawn into lungs after normal expiration (tidal + above tidal) = 3L
What is an obstructive lung disease?
shortness of breath due to difficult exhaling all air from lungs
ex. asthma, cystic fibrosis
What is a restrictive lung disease?
inability to fully fill their lungs with air, restricted from fully expanding
ex: interstitial lung disease
A patient performs an expiratory forced vital capacity maneuver. His FVC is 2L and his FEV1 is 1 liter. Based on your knowledge of these numbers you would predict this person suffers from?
an obstructive lung disease
What is the formula for PaO2?
PaO2 = PIO2 - PaCO2/R
R=0.8
What is formula for PIO2?
PIO2 = oxygen concentration * (Pbar - 47 mmHg) oxygen c (normal) = 0.21 Pbar (normal) = 760 mmHg
A patient begins to hyperventilate while sitting in a clinic on Miami Beach and breathing room air. Over the ensuing 1 minute, his PaCO2 drops to 20 mmHg. What is his PaO2 at that moment in time?
125 mmHg
With respect to the path of O2 diffusion, the proper order for the movement of oxygen across the pulmonary capillary membrane is:
alveolar epithelium, interstitial space, capillary basement membrane, blood
When a gas in the blood, such as oxygen, fails to reach diffusion equilibrium with the alveolar air as it leaves the pulmonary capillary bed is said to be
diffusion limited
What does it mean to be perfusion limited?
oxygen levels reach equilibrium before the blood leaves the alveoli area, no more oxygen can be transported
What does it mean to be diffusion limited?
Interstitial space between the alveoli and capillary is too large, preventing complete oxygen transfer
Under normal physiologic conditions, the maximum capacity of O2 that Hb can carry is approximately
1.34 ml O2
OR
200 mls per liter
How many grams of hemoglobin are present in the blood?
15 g Hb / 100 mL blood
How much O2 is delivered to the body per minute? How much of that is consumed?
1000 mLs of O2 / min, only 250 mLs of O2 are consumed
What is the equation for how much oxygen hemoglobin can carry per liter of blood?
Carrying capacity * hemoglobin concentration * %saturation
units
Which of the following will increase the content of arterial oxygen?
- increased hemoglobin conc.
- decreased hemoglobin saturation
- decreased PaO2
- decreased O2 solubility
increased hemoglobin concentration
What is Henry’s Law? Solubility of O2?
Concentration of a dissolved gas = solubility of gas * deltaP of gas
Solubility of O2 = 0.0031 mLs O2/mmHg / 100 mLs blood
What is the formula for % Hb saturation?
% saturation = actual content / capacity
capacity at 100% saturation is 20.1
What happens to our oxyhemoglobin when we exercise and our metabolism and temperature increase?
Less O2 binding to Hb because of the O2 pressure increase
What is also released when exercise is occurring to help with oxygen release from Hb?
2,3-diphosphoglycerate, produced in anaerobic environments
Does a decrease in pH/increase in PaCO2 cause an increase or decrease in oxygen release from Hb?
increase, they both have effect but are more significant when combined
What is the total oxygen content composed of?
sum of dissolved and hemoglobin bound oxygen
What is polycythemia?
increase in hemoglobin/RBCs, oxygen therapy will not help with this disease
What is anemia?
decrease in hemoglobin/RBCs, oxygen therapy will not help with this disease
How does oxygen content change in CO poisoning?
Decrease in saturation due to present CO2 on hemoglobin, dissolved remains the same
How do we treat CO poisoning?
Increase dissolved O2 content via atmospheric pressure, allows for overall O2 content increase
How do we increase oxygen delivery (qualitatively)?
Increased heart rate, stroke volume, Hb concentration