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43 Cards in this Set
- Front
- Back
what does oxygen saturation equal?
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saO2 = oxygen combined with Hb/ oxygen carrying capacity of Hb (all times 100)
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what percentage of oxygen is carried dissolved in the plasma?
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2%
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waht percentage of o2 is bound to Hb?
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98%
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in 100ml of blood, how many grams of Hb are there?
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15g Hb
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what is the oxygen carrying capacity of Hb?
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15g x 1.34 ml O2/g = 20 ml
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what is the oxygen content of teh blood (value) and what is it measured in terms of?
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sum of dissolved and bound forms of O2
20 ml O2/100 ml of blood |
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besides expressing oxygen content in terms of ml O2 per 100 ml of blood, what is another way you can express O2 content?
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%vol
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waht is teh O2 content of arterial blood? venous blood? (expressed in %vol)
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arterial blood = 20%vol
venous blood = 15% vol thus, for each time blood circulates, 5%vol of oxygen is taken up by the tissues |
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what does P50 refer to?
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the partial pressure of oxygen at which 50% of teh Hb is saturated
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what is the Hb saturation at PaO2 =
a) 100 mmHg b) 60 mmHg c) 27 mmHg |
1) 99%
2) 90% 3) 50% |
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at what partial pressure of O2 will the Hb O2 sat be 50%
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27 mmhg
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across waht partial pressures is the plateau region of the oxgyhemoglobin dissociation curve?
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b/w 60-100 mmHg
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waht is something that would shift the oxyHb dissoc curve to the left?
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CO (interferes with O2 unloading at tissues)
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what are 4 things that could shift the oxyHb dissoc curve to the right?
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decreased pH
2,3 BPG (product of anaerobic metab of glu) PCO2 temp |
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waht does the Bohr shift refer to?
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the movement of the oxyHb dissoc curve to the right due to increasing PCO2
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what will anemia do to the oxyHb dissoc curve?
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nothing - the Hb that is there can be fully saturated
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what will anemia do to the O2 content vs. PO2 curve?
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shift it downwards (due to less Hb in the blood, your O2 content will be lower)
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how will CO affect the O2 content vs. PO2 curve?
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shift it downwards (greater affinity for Hb than O2)
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what do you call Hb that has CO bound to it?
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carboxyhemoglobin
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the absence of cyanosis indicates normal oxygen transport. T/F?
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F. Your saturation may be normal, but you may be anemic and still have a low O2 content
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waht is the CO2 content of arterial blood? venous?
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arterial: 48%vol
venous: 52%vol |
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what is the three forms CO2 is transported through teh blood?
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1. dissolved [5%]
2. as bicarb [90%] 3. bound to Hb (carbamino cmpd) [5%] |
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what does the haldane shift refer to?
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the way in which the state of oxygenation of Hb affects the CO2 dissociation curve. Deoxygenated Hb is better at binding H+ and in turn assisting the blood to load more CO2 to carry away from teh tissues
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what part of the lungs do interstitial lung diseases affect?
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the lung parenchyma - distal to the bronchioles. the space in b/w the alveoli and endothelium (usually their BM's are fused - but now they are filled with collagen/inflamm cells/granulomas)
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tell me the 4 most common forms of interstitial lung disease
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1. UIP - usual interstitial pneumonia
2. EAA - extrinsic allergic alveolitis 3. sarcoidosis 4. pneumoconioses such as asbestosis |
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what drugs are implicated in causing UIP
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1. chemotherapy agents
2. amiodarone (anti-arrhythmic) 3. nitrofurantion 4. antidepressants |
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describe how fibroblast foci occur in uip
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initial epithelial injury --> local fibrin deposition and outgorwht of fibroblasts from the interstitum to organize the fibrin. Due to a lack of plasminogen activating factor, the fibrin is not broken down --> fibroblast foci --> become interstitial fibrous tissue (granulation tissue)
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why is there loss of alveoli in UIP?
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the interstitial fibrous tissue accumulates - alveolar collapse
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5 possible etiologies of UIP
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-idiopathic (most)
-collagen vascular diseases (SLE, RA, Scleroderma) -Drug induced (chemotherapeutic agents, amiodarone, nitrofurantion) -familiarl UIP -pneumoconioses (asbestosis) |
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will CXR for UIP show nodular/reticulonodular/reticular pattern?
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reticulonodular pattern
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where is UIP most manifest (waht part of lung)
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lower lobes, periphery of lung, periphery of lobules
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waht are 2 things that could trigger the initial injury in UIP?
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environmental agesn - eg. cigarette smoke
viral infxn: hep c, EBV |
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how are immunological factors involved in UIP?
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auto-ABs that react with aveolar epith
Th2 lymphocytes predominate - stimulates fibroblast prolif |
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role of cytokines in UIP
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increased number of profibrotic cytokines in UIP
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UIP fibroblast abnormalities
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abnormalities found in vitro:
-increased motility -increased rate of proliferation -achorage indep growth -resis to apoptosis |
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diff b/w anoxia and asphyxia
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anoxia - no oxygen
asphyxia - no oxygen and CO2 accumulation |
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does P(A-a)O2 increase/decrease with age? formula?
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increases with age; A-a gradient =(age/4)+4
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as you increase FI02, are you going to increase/decrease your A-a gradient?
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decrease
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describe the anatomic shunt that occurs in normal healthy individuals and accounts for 1/3 of A-a difference
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a) part of teh coronary circulation drains into the thebesian veins, and into the LV
b) part of the bronchial ciculation empties into pulm veins returning to the LA |
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what accounts for 2/3 of the A-a gradient?
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the inherent V/Q mismatch that occurs in our lungs due to gravity and intrapleural P
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does hypoxemia refer to low partial pressure of oxygen in the blood, or low oxygen content?
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low partial pressure * THIS IS REALLOY IMPT TO UNDERSTAND (think about anemia, hemoglobinopathies which reduce oxygen content, but don't change PaO2. Also think about CO poisoning...which also decrease the oxygen
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will anemia cause a decrease in oxygen content, PaO2, or both?
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oxygen content. The reason why anemia isn't considered to cause hypoxemia is because it doesn't cause a decrease in PaCO2.
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Could histotoxic poisins such as cyanide be a cause of hypoxemia?
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NO. While it casues tissue hypoxia, it doesn't change teh PaO2 - thus it does not cause hypoxemia
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