Blood pressure, capillary and vasoconstriction?
I have that vasoconstriction increases blood pressure, but why is it that in blood capillaries, the blood pressure drops.
It seem like a contradiction, so can you clarify this?
Thanks
Answers:
1. "Blood pressure" means "blood pressure in arteries" unless explicitly stated as the pressure surrounded by a particular vessel or set of vessels e.g. jugular venous pressure, central venous pressure, etc.
2. The "resistance vessels" surrounded by the circulation (the ones that have the most resistance and biggest effect on blood pressure) are the very small arteries (the arterioles). These are downstream of the arteries (where "blood pressure" is measured) and upstream of capillaries.
3. Vasoconstriction (of the resistance vessels) - arterial pressure go up, capillary pressure goes down.
So no contradiction, just have to be aware that unspecified blood pressure = arterial blood pressure.
Capillaries vasoconstrict below "special" circumstances such as an adrenaline rush (eg. fear) or if you have internal bleeding. This is so that blood can be sent to our vital organs, like our brain and heart. Our body is massively happy to sacrifice the skin of our nose, fingers etc (like during frostbite) to keep our key organs alive.
Blood pressure is measured from arteries which are palpable (feelable) from the skin, eg. the radial (wrist), carotid (neck). The arteries are like the highways and the capillaries are close to the back alleys, so when blood is redirected away from the capillaries (during vasoconstriction) and into the arteries (for quicker access to the heart), the amount of blood within the arteries increases, therefore distending (expanding) more, therefore creating a larger pulse, which measures as a higher blood pressure. And the amount of blood within the capillaries obviosuly decreases, which decreases the pressure surrounded by there.
Hope that makes sense, sorry if I dumbed it down too much.
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It seem like a contradiction, so can you clarify this?
Thanks
Answers:
1. "Blood pressure" means "blood pressure in arteries" unless explicitly stated as the pressure surrounded by a particular vessel or set of vessels e.g. jugular venous pressure, central venous pressure, etc.
2. The "resistance vessels" surrounded by the circulation (the ones that have the most resistance and biggest effect on blood pressure) are the very small arteries (the arterioles). These are downstream of the arteries (where "blood pressure" is measured) and upstream of capillaries.
3. Vasoconstriction (of the resistance vessels) - arterial pressure go up, capillary pressure goes down.
So no contradiction, just have to be aware that unspecified blood pressure = arterial blood pressure.
Capillaries vasoconstrict below "special" circumstances such as an adrenaline rush (eg. fear) or if you have internal bleeding. This is so that blood can be sent to our vital organs, like our brain and heart. Our body is massively happy to sacrifice the skin of our nose, fingers etc (like during frostbite) to keep our key organs alive.
Blood pressure is measured from arteries which are palpable (feelable) from the skin, eg. the radial (wrist), carotid (neck). The arteries are like the highways and the capillaries are close to the back alleys, so when blood is redirected away from the capillaries (during vasoconstriction) and into the arteries (for quicker access to the heart), the amount of blood within the arteries increases, therefore distending (expanding) more, therefore creating a larger pulse, which measures as a higher blood pressure. And the amount of blood within the capillaries obviosuly decreases, which decreases the pressure surrounded by there.
Hope that makes sense, sorry if I dumbed it down too much.
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