Why clotting of blood does not takes place in lungs?

P

plakhapate

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When Oxygen comes in contact with blood , clotting of blood takes place, hence flow of blood stops through the wound.

If this is the case then why blood does not clot in lung when it comes in contact with Oxygen?

P.J.LAKHAPATE
plakhapate@rediffmail.com
 
plakhapate said:
When Oxygen comes in contact with blood....
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Exposure to oxygen is not what activates clotting. The clotting cascade is activated by the rupture of endothelial cells (ie. blood vessels). This event is independant to whether or not any blood comes in contact with the outside air.
 
Herc:

The intrinsic clotting pathway isn't activated by endothelial damage.

Why wouldn't intrinsic clotting occur in the lungs? Is it because the extrinsic pathway must be activated first?
 
The blood clotting cascade produces a fibrin clot that is formed by the interplay of the intrinsic and extrinsic pathways which feed into a final common pathway. The intrinsic pathway begins with the activation of factor XII by contact with abnormal surfaces produced by injury. The extrinsic pathway is triggered by trauma, which activates factor VII and releases a lipoprotein, called tissue factor, from blood vessels.

-- Biochemistry (5th Ed) by Stryer et al.
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Having said that, I'm not entirely sure what "abnormal surfaces produced by injury" and "trauma" specifically refer to.
 
Last edited:
desi said:
What about pulmonary emboli?
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Well, maybe somewhat the right idea but the wrong page. That's a clot in the pulmonary artery that traveled from somewhere else in the body and is blocking the blood flow to the lungs. It not actually a clot in the lungs themselves. However, it can lead to severe coughing which can rupture capillaries and cause blood to enter the lungs BUT still no clots form in there.
 
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