silver
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A
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| Addicudo
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b. increased RBC sickling in the peripheral tissues
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| nimer1456
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B
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| drduck
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?????
is that the painful symptoms arise bcos of the sickling...or ois it bcos of the obstruction of the small vessels due to increase interaction between RBC and the endothelium...which leads to....painful ischemia....
i will go with the option A..
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| peraspera
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pathogenesis of sickle cell anemia is INTRINSIC DEFECT WITH PREDOMINANTLY EXTRAVASCULAR HEMOLYSIS. Painful vaso-occlusive crises in which sickle cell block the microcirculation, causing ischemic damage.
This process damages the red blood cell membrane, and can cause the cells to become stuck in blood vessels. This deprives the downstream tissues of oxygen and causes ischemia and infarction, which may cause organ damage, such as stroke. New erythrocytes are quite elastic, which allows the cells to deform to pass through capillaries. Often a cycle occurs because as the cells sickle, they cause a region of low oxygen concentration which causes more red blood cells to sickle. Repeated episodes of sickling causes loss of this elasticity and the cells fail to return to normal shape when oxygen concentration increases. These rigid red blood cells are unable to flow through narrow capillaries, causing vessel occlusion and ischaemia.
A vaso-occlusive crisis is caused by sickle-shaped red blood cells that obstruct capillaries and restrict blood flow to an organ, resulting in ischemia, pain, and organ damage
it looks like due to adhesion of RBC to endothelium.
Edited by peraspera on 06/10/07 - 06:24 AM
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| drduck
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thank u peraspera .....
nice explanation....
so what is the answer????
Edited by drduck on 06/10/07 - 07:22 AM
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| ssrpk
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yes it shoudl be because of increased sickling! they are the nidus around which RBC's stick to endothelium
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| drduck
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still...not clear....me007...its time to post the answer.
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| silver
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to my understanding of the ques., it's asking what is causing the painful crisis. in that case, the ans. is the adherence of the RBCs to the endothelium. the sickling of the RBCs is just the beginning of the pathology, but it's the actual adherence to the endothelium and eventual occlusion of the vessel that leads to the painful crisis.
let's see what me007 has to say..
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Everything turns out ok in the end. If it's not ok, then it's not the end.
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| me007
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yes, it's A, totally correct
when it was my 199th qs i ws bit cofused, buzzwods do their job
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| epica
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Is this Q from your exam?
How was your exam?
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| peraspera
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last sentence from june 9
ADHERENCE OF RBS TO ENDOTHELIUM-sickle cell block the microcirculation, causing ischemic damage. This deprives the downstream tissues of oxygen and causes ischemia and infarction, which may cause organ damage, such as stroke-PAINFUL CRISIS. The procedure of sickling does not give painful crisis.
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| inkspot
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well the driving force for this pathology is sickling, normal rbc's dont stuck into endothelium. in peripheral tissues the O2 conc is low and there is more sickling !!! leading to ischemia and painful crises.
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| new_n_lost
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no Guys the ACtual Driving Force For the Painful Crisis is Hypoxemia. THe fact that the in a Sickle Cell Anemia pt we dont often see the Crisis cos the Pt hasnt undergone any hypoxemic Stress which further Induces the Sickling of Already Sickled Cells. If the Sickle cells were to alone cause the Painful Crisis then the disease wud not have been life Compatible. However, When there is hypoxia there is a further sickling of RBCs the Structurally Altered RBCs attach themselves to Vessel Walls thus leading to the Painful Crisis.
This Phenomenon is excellently explained in Robbins.
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| epica
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NNL, this is the best explanation.
Everything in Robbins....
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| whournameiz
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tricky tricky would have totally gotten this one wrong
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| epica
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to whournameiz
Pl check your PM (from me)
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