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ADH --> Negative Feedback Question (EK)

Discussion in 'MCAT Discussions' started by axp107, Jun 11, 2007.

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  1. axp107

    axp107 UCLA 09': Italian Pryde

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    Maybe its just the wording of the question.. but check this out:

    1) If ADH holds water in the body decreasing urine output and increasing blood pressure does a person with high blood pressure have a high or low ADH level?

    I though "DOES" implies present tense.. so I said high ADH. You would expect a person with high bp to have high ADH.. seemed logical

    BUT, you're supposed to view this question as a correction mechanism..
    that the bp is already high.. what must be done to lower it?? wtf?

    Is it just me or is the grammar in the question realllly reallly ambiguous?

    If the question asked "How would ADH levels respond to the high bp" I would have gotten it right.
  2. zackscoot

    zackscoot

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    The way ADH works is by respond to blood pressure. A person with a low BP will result in an increase in ADH in order to restore the normal BP... But if someone has a high BP then their ADH level will be very low.

    ADH secretion is responding/controled by blood pressure. Not the otherway around. Meaning that low BP cause ADH secretion. but ADH secretion does not cause HIGH BP!!!!!
  3. DrMT

    DrMT 182?

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    tricky tricky
  4. majik1213

    majik1213

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    zackscoot is absolutely right .. I think of negative feedback as working like a thermostat does .. If the room gets too cold, the sensor triggers a heater. But the heater won't always be on, even though it heats the room (so the heater increases temperature much like ADH increases BP, but neither are always "on")
  5. Selector

    Selector

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    This topic used to confuse me... Then I was hipped to a very easy way to think about it : Your body uses hormones to RESPOND to a non-baseline condition... ie your body would not increase ADH thereby increasing its blood pressure (why would it do that? it would be harming itself) Anytime you have an "elevated _______" or "decreased _______" your body is going to release the necessary hormones to bring itself back to normal.
    As long as you think about it this way, you should have no problems answering feedback questions
  6. axp107

    axp107 UCLA 09': Italian Pryde

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    Oh.. good point.. stupid me.. thanks

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