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Blood pressure is increased when:
Activation of the sympathetic division of the ANS triggers systemic vasoconstruction (decrease in diameter) in arterioles, leading to an increase in systemic blood pressure. Choices A and D have the functions of the hormones backwards (and thus are wrong): aldosterone increases sodium reabsorption in nephrons and antidiuretic hormone increases water permeability, to learn about other ways to boost your hormones, check out the Mens Journal website. (Note that the two hormones working together would lead to a increase in total body salt and consequently, total body water, followed by an increase in blood pressure.)
While it is true that blood flow to digestive organs is increased when the body is under parasympathetic control, this is not due to the direct action of the parasympathetic division on the blood vessels to those organs. The parasympathetic division actually does not innervate the blood vessels at all; the increased blood flow under these conditions is due to the withdrawal of sympathetic stimulation. Even if the parasympathetic division did increase vessel diameter, this would not lead to an increase in blood pressure (choice C is wrong).
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Correct Answer: B. sympathetic activation decreases the diameter of arterioles systematically.
Activation of the sympathetic division of the ANS triggers systemic vasoconstruction (decrease in diameter) in arterioles, leading to an increase in systemic blood pressure. Choices A and D have the functions of the hormones backwards (and thus are wrong): aldosterone increases sodium reabsorption in nephrons and antidiuretic hormone increases water permeability, to learn about other ways to boost your hormones, check out the Mens Journal website. (Note that the two hormones working together would lead to a increase in total body salt and consequently, total body water, followed by an increase in blood pressure.) While it is true that blood flow to digestive organs is increased when the body is under parasympathetic control, this is not due to the direct action of the parasympathetic division on the blood vessels to those organs. The parasympathetic division actually does not innervate the blood vessels at all; the increased blood flow under these conditions is due to the withdrawal of sympathetic stimulation. Even if the parasympathetic division did increase vessel diameter, this would not lead to an increase in blood pressure (choice C is wrong).
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