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43 Cards in this Set

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what does oxygen saturation equal?
saO2 = oxygen combined with Hb/ oxygen carrying capacity of Hb (all times 100)
what percentage of oxygen is carried dissolved in the plasma?
2%
waht percentage of o2 is bound to Hb?
98%
in 100ml of blood, how many grams of Hb are there?
15g Hb
what is the oxygen carrying capacity of Hb?
15g x 1.34 ml O2/g = 20 ml
what is the oxygen content of teh blood (value) and what is it measured in terms of?
sum of dissolved and bound forms of O2

20 ml O2/100 ml of blood
besides expressing oxygen content in terms of ml O2 per 100 ml of blood, what is another way you can express O2 content?
%vol
waht is teh O2 content of arterial blood? venous blood? (expressed in %vol)
arterial blood = 20%vol
venous blood = 15% vol

thus, for each time blood circulates, 5%vol of oxygen is taken up by the tissues
what does P50 refer to?
the partial pressure of oxygen at which 50% of teh Hb is saturated
what is the Hb saturation at PaO2 =
a) 100 mmHg
b) 60 mmHg
c) 27 mmHg
1) 99%
2) 90%
3) 50%
at what partial pressure of O2 will the Hb O2 sat be 50%
27 mmhg
across waht partial pressures is the plateau region of the oxgyhemoglobin dissociation curve?
b/w 60-100 mmHg
waht is something that would shift the oxyHb dissoc curve to the left?
CO (interferes with O2 unloading at tissues)
what are 4 things that could shift the oxyHb dissoc curve to the right?
decreased pH
2,3 BPG (product of anaerobic metab of glu)
PCO2
temp
waht does the Bohr shift refer to?
the movement of the oxyHb dissoc curve to the right due to increasing PCO2
what will anemia do to the oxyHb dissoc curve?
nothing - the Hb that is there can be fully saturated
what will anemia do to the O2 content vs. PO2 curve?
shift it downwards (due to less Hb in the blood, your O2 content will be lower)
how will CO affect the O2 content vs. PO2 curve?
shift it downwards (greater affinity for Hb than O2)
what do you call Hb that has CO bound to it?
carboxyhemoglobin
the absence of cyanosis indicates normal oxygen transport. T/F?
F. Your saturation may be normal, but you may be anemic and still have a low O2 content
waht is the CO2 content of arterial blood? venous?
arterial: 48%vol
venous: 52%vol
what is the three forms CO2 is transported through teh blood?
1. dissolved [5%]
2. as bicarb [90%]
3. bound to Hb (carbamino cmpd) [5%]
what does the haldane shift refer to?
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
what part of the lungs do interstitial lung diseases affect?
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)
tell me the 4 most common forms of interstitial lung disease
1. UIP - usual interstitial pneumonia
2. EAA - extrinsic allergic alveolitis
3. sarcoidosis
4. pneumoconioses such as asbestosis
what drugs are implicated in causing UIP
1. chemotherapy agents
2. amiodarone (anti-arrhythmic)
3. nitrofurantion
4. antidepressants
describe how fibroblast foci occur in uip
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)
why is there loss of alveoli in UIP?
the interstitial fibrous tissue accumulates - alveolar collapse
5 possible etiologies of UIP
-idiopathic (most)
-collagen vascular diseases (SLE, RA, Scleroderma)
-Drug induced (chemotherapeutic agents, amiodarone, nitrofurantion)
-familiarl UIP
-pneumoconioses (asbestosis)
will CXR for UIP show nodular/reticulonodular/reticular pattern?
reticulonodular pattern
where is UIP most manifest (waht part of lung)
lower lobes, periphery of lung, periphery of lobules
waht are 2 things that could trigger the initial injury in UIP?
environmental agesn - eg. cigarette smoke

viral infxn: hep c, EBV
how are immunological factors involved in UIP?
auto-ABs that react with aveolar epith

Th2 lymphocytes predominate - stimulates fibroblast prolif
role of cytokines in UIP
increased number of profibrotic cytokines in UIP
UIP fibroblast abnormalities
abnormalities found in vitro:
-increased motility
-increased rate of proliferation
-achorage indep growth
-resis to apoptosis
diff b/w anoxia and asphyxia
anoxia - no oxygen
asphyxia - no oxygen and CO2 accumulation
does P(A-a)O2 increase/decrease with age? formula?
increases with age; A-a gradient =(age/4)+4
as you increase FI02, are you going to increase/decrease your A-a gradient?
decrease
describe the anatomic shunt that occurs in normal healthy individuals and accounts for 1/3 of A-a difference
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
what accounts for 2/3 of the A-a gradient?
the inherent V/Q mismatch that occurs in our lungs due to gravity and intrapleural P
does hypoxemia refer to low partial pressure of oxygen in the blood, or low oxygen content?
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
will anemia cause a decrease in oxygen content, PaO2, or both?
oxygen content. The reason why anemia isn't considered to cause hypoxemia is because it doesn't cause a decrease in PaCO2.
Could histotoxic poisins such as cyanide be a cause of hypoxemia?
NO. While it casues tissue hypoxia, it doesn't change teh PaO2 - thus it does not cause hypoxemia