queries...

[Budding dentist]

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heyy...can someone please explain these 2 statements..

1. the max drop in blood pressure occurs in the arterioles?!?!?...why?

2. hypocapnea caused by hyperventilation causes drop in the blood pressure...why does the blood pressure drop??

 

[Ride]

1. The max drop in BP occurs in the arterioles bc they have the highest resistance in the systemic circulation (ie. versus the aorta, capillaries, vena cava, etc.). Higher resistance to flow causes the blood pressure to drop.

Resistance is directly proportional to length of the vessel; so, the longer the vessel, the more resistance. Resistance is indirectly proportional to radius of the vessel to the fourth power (r^4); so, a very small decrease in the radius of the vessel would cause relatively large increase in resistance.

I think the drop in BP across the arterioles has more to do with the decreased radius than it does with the increased vessel length.

Note: Resistance = [8*(viscosity of blood) * (length of vessel)] / [(pi) * (r^4)]

2. ?

 

[Budding dentist]

...........yup..that makes sense....thanx so much! 🙂