TBR Immno Passage

[greenseeking]

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Hi
This is from TBR Passage X page 311 Q 65:

Passage Exerpt:
A common sign of septic shock is widespread activation of coagulation leading to widespread intravascular clotting. Microbial products activate Factor XII a molecule involved in blood clotting. Activation of this factor initiates the intrinisic coagulation pathway and also the bradykinin pathway. Bradykinin is a potent vasodilator and also increases the permeability of vascular endothelial cells.

Question #65.
In an experiment, a sepsis patient is treated with anti-factor XII antibodies. After treatment one would expect to see a:

a.total lack of intravascular clotting
b.rise in intravascular clotting
c.rise in the patient's Blood pressure
d.Decrease in the patient's Blood pressure

Answer is C.

How come it's not D? The Factor XII causes clotting, vasodilation, (raises BP). If you prevent the factor XII from working, you should get a decrease in Blood pressure no???
Back of the book's explanation is not making sense...

 

[greenseeking]

Weird-- I read about bradykinin just now and vasodilation means a DECREASE in blood pressure..... I'm not quite sure why though. according to wikipedia, Vasodilation increases the diameter of the blood vessels, which increases the blood flow. This decreases resistance which increases blood pressure. Does anyone understand how vasodilation affects resistance of a vessel?

So I guess the answer C does make sense.

 

[cloak25]

Activation of factor XII initiates the bradykinin pathway = decrease BP. If you treat the patient with ANTI-factor XII antibodies, you get no more factor XII which means you won't activate bradykinin pathway = increase BP. right?

 

[ingramw1202]

Treating a patient with antifactor x whatever antibodies will deplete endogenous levels of that protein. In the passage, it is states that antifactor x results in coagulation and blood clotting. Treating a patient with an antibody against that would decrease the amount of antifactor x, resulting in no clot formation. Because no clots form, blood vessels are not obstructed. Because they are not obstructed, and permeability of tissue increases, then the blood vessel cross sectional area will increase, thus decreasing blood pressure. Hope this helps!

 

[ingramw1202]

Sorry not antifactor but factor x lol. 🙂

 

[ingramw1202]

But since that bradykinin pathway is not activated by depleted factor xii, then normal decrease in blood pressure can not occur. So instead bp will increase. Does this make sense?

 

[MedPR]

Septic shock leads to clotting, which leads to venule blood pooling, which leads to hypotension.

 

[MedPR]

Hi
This is from TBR Passage X page 311 Q 65:

Passage Exerpt:
A common sign of septic shock is widespread activation of coagulation leading to widespread intravascular clotting. Microbial products activate Factor XII a molecule involved in blood clotting. Activation of this factor initiates the intrinisic coagulation pathway and also the bradykinin pathway. Bradykinin is a potent vasodilator and also increases the permeability of vascular endothelial cells.

Question #65.
In an experiment, a sepsis patient is treated with anti-factor XII antibodies. After treatment one would expect to see a:

a.total lack of intravascular clotting
b.rise in intravascular clotting
c.rise in the patient's Blood pressure
d.Decrease in the patient's Blood pressure

Answer is C.

How come it's not D? The Factor XII causes clotting, vasodilation, (raises BP). If you prevent the factor XII from working, you should get a decrease in Blood pressure no???
Back of the book's explanation is not making sense...

Vasodilation does not raise BP. Many anti-hypertensives are vasodilators.

 

[greenseeking]

Thanks everyone. Makes sense now!! 🙂 I'm very grateful.