sympathetic, blood vessels constrict???

[joonkimdds]

sympathetic nervous system is fight or flight.
It should increase our body metabolism in every way except eating and sleeping.

heart rate goes up, respiration increase, bronchioles dilate to increase air flow...

but then I wrote that blood vessels constrict.

If it constricts, doesn't it slow down the blood flow?

my human physiology note says vasoconstriction decreases blood flow.

I think sympathetic nervous system should increase the blood flow but I am not sure if i am wrong or the note is wrong.

Could someone verify this?

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[peyman2002]

We have vasoconstriction in gastrointestinal organs but vasodilation in heart,brain and muscles.

 

[joonkimdds]

We have vasoconstriction in gastrointestinal organs but vasodilation in heart,brain and muscles.

I am assuming that I have to memorize it in two different ways like that instead of saying blood vessels in general vasoconstrict/vasodialate?

 

[ozzie33]

Our teacher said vasoconstriction in the fight or flight response occurs in digestive organs, and also in the skin, as to minimize blood loss if an injury occurs

 

[pbure9]

Right, you're shunting away blood from the digestive tract and skin to the heart, muscles and lungs.

But know that with vasoconstriction, you need an increased heart rate and blood pressure to overcome that (which is seen in the sympathetic nervous system). This all leads to the "fight or flight response". In vasodilation, blood flows more freely so heart rate is lower.

 

[achilles2]

adrenaline has a higher affinity for beta receptor sites then alpha.

So a low to mild epi concentration you will selectively bind beta2 sites in vasculature and cause dilation....at very high doses of adrenaline you will cause constriction (thats why dentists use it with anasthetic to keep it localized)


systemically during fight or flight you should cause vasodilation to muscle systems and constrict digestive flow

 

[jay47]

adrenaline has a higher affinity for beta receptor sites then alpha.

So a low to mild epi concentration you will selectively bind beta2 sites in vasculature and cause dilation....at very high doses of adrenaline you will cause constriction (thats why dentists use it with anasthetic to keep it localized)


systemically during fight or flight you should cause vasodilation to muscle systems and constrict digestive flow

Good one, but to be even more specific, you will activate alpha 1 receptors in digestive organ blood vessels (thus restricting blood flow to the digestive organs), and beta 2 receptors in digestive smooth muscle (relaxing digestive muscle), concomitantly inhibiting the actions of the digestive organs...

...Although this is prolly WAY more than you need to know for the DAT...

The important thing to remember is that the action of the organ you are looking at depends on its receptors. Alpha one, Beta one, generally cause contraction of things. Alpha two [arteries, contrxn of veins, smooth muscle], Beta 2, generally cause relaxation.

Alpha one: Wikipedia..."It causes vasoconstriction in many blood vessels including those of the skin & gastrointestinal system and to kidney (renal artery)[5] and brain[6]. "

 

[joonkimdds]

Right, you're shunting away blood from the digestive tract and skin to the heart, muscles and lungs.

But know that with vasoconstriction, you need an increased heart rate and blood pressure to overcome that (which is seen in the sympathetic nervous system). This all leads to the "fight or flight response". In vasodilation, blood flows more freely so heart rate is lower.

ok that makes sense.

 

[mermaid66]

just to add something real quick
in fight or flight besides digestive system, the bloff flows to kidney also decrease.
wish you luckkkk

 

[achilles2]

Good one, but to be even more specific, you will activate alpha 1 receptors in digestive organ blood vessels (thus restricting blood flow to the digestive organs), and beta 2 receptors in digestive smooth muscle (relaxing digestive muscle), concomitantly inhibiting the actions of the digestive organs...

...Although this is prolly WAY more than you need to know for the DAT...

The important thing to remember is that the action of the organ you are looking at depends on its receptors. Alpha one, Beta one, generally cause contraction of things. Alpha two [arteries, contrxn of veins, smooth muscle], Beta 2, generally cause relaxation.

Alpha one: Wikipedia..."It causes vasoconstriction in many blood vessels including those of the skin & gastrointestinal system and to kidney (renal artery)[5] and brain[6]. "

well played

I didn't mention that the vasculature to the gut had a higher number of alpha 1 receptors then beta 2, thus adrenaline even at low concentration will occupy mostly alpha 1's in the digestive system

adrenaline also works on the heart via beta 1 receptors (increase chronotrophic and ionotrophic effects) and nor-epi tends to work by alpha 1 sites on the heart (nor-epi has a higher affinity for alpha 1 sites over beta 1 and 2 unlike adrenaline.

 

[jay47]

well played

I didn't mention that the vasculature to the gut had a higher number of alpha 1 receptors then beta 2, thus adrenaline even at low concentration will occupy mostly alpha 1's in the digestive system

adrenaline also works on the heart via beta 1 receptors (increase chronotrophic and ionotrophic effects) and nor-epi tends to work by alpha 1 sites on the heart (nor-epi has a higher affinity for alpha 1 sites over beta 1 and 2 unlike adrenaline.

Lol, let's start a physiology class together! Sounds like we're both ready for dental school to get started, I know I am...