Sympathetic System

Jacob_Arulandu
Jacob_Arulandu Posts: 192

MCAT Student

🔬
edited March 13 in Pre-Med Success Community

Something that has always confused me is vasoconstriction vs vasodilation and what that means for blood pressure, blood volume, etc… Also, does vasoconstriction or vasodilation happen under sympathetic activation and for what reason?

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  • Ae-Ri
    Ae-Ri Posts: 308

    Moderator

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    Answer ✓

    Hi Jacob. Remember that vasoconstriction/dilation isn't an all or none response for everywhere in the body. This is going to be happening locally, depending on what the body needs. For instance, if I'm in a fight/flight response, I'd need to ensure that my muscles have adequate supply of oxygen, so vasodilation towards the muscles is likely going to happen, which means I'd probably vasoconstrict the blood supply going to digestion. Overall, yes sympathetic activation will cause an increase in blood pressure though.

  • Ae-Ri
    Ae-Ri Posts: 308

    Moderator

    🚨
    Answer ✓

    It's common for people to think that sympathetic = constriction/dilation, and parasympathetic means = nothing, but it's not as simple as that. Both sympathetic and parasympathetic will constrict/dilate based on where that blood needs to go. Parasympathetic prioritizes digestion and more basal processes, so constricting the blood away from the muscles and dilating the areas for digestion.

Answers

  • Ae-Ri
    Ae-Ri Posts: 308

    Moderator

    🚨
    Answer ✓

    Hi Jacob. Remember that vasoconstriction/dilation isn't an all or none response for everywhere in the body. This is going to be happening locally, depending on what the body needs. For instance, if I'm in a fight/flight response, I'd need to ensure that my muscles have adequate supply of oxygen, so vasodilation towards the muscles is likely going to happen, which means I'd probably vasoconstrict the blood supply going to digestion. Overall, yes sympathetic activation will cause an increase in blood pressure though.

  • Ae-Ri
    Ae-Ri Posts: 308

    Moderator

    🚨
    Answer ✓

    It's common for people to think that sympathetic = constriction/dilation, and parasympathetic means = nothing, but it's not as simple as that. Both sympathetic and parasympathetic will constrict/dilate based on where that blood needs to go. Parasympathetic prioritizes digestion and more basal processes, so constricting the blood away from the muscles and dilating the areas for digestion.

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