COMEDK 2007 MCQ Answer 32
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The correct answer is A
VASCULAR (ARTERIOLAR) CONTROL
Mainly via the sympathetic nervous system: tonic discharge of sympathetic nerves enhances the basal tone of the arterioles (via neurally released noradrenaline, NAd). There is, with a few notable exceptions, little parasympathetic innervation of arterioles.
Change in this the sympathetic discharge rate either vasoconstricts or vasodilates arterioles:
↑ sympath. activity → arteriolar vasoconstriction
↓ sympath. activity → arteriolar vasodilatation
This forms part of reflex control of the CVS to regulate MAP.
Because adrenergic influences are mediated by α-adrenoceptors in the VSM (controls TPR), and β-adrenoceptors in the heart (controls CO), selective α or β blockers can be used to block one or the other.
VASCULAR (ARTERIOLAR) CONTROL
Mainly via the sympathetic nervous system: tonic discharge of sympathetic nerves enhances the basal tone of the arterioles (via neurally released noradrenaline, NAd). There is, with a few notable exceptions, little parasympathetic innervation of arterioles.
Change in this the sympathetic discharge rate either vasoconstricts or vasodilates arterioles:
↑ sympath. activity → arteriolar vasoconstriction
↓ sympath. activity → arteriolar vasodilatation
This forms part of reflex control of the CVS to regulate MAP.
Because adrenergic influences are mediated by α-adrenoceptors in the VSM (controls TPR), and β-adrenoceptors in the heart (controls CO), selective α or β blockers can be used to block one or the other.
Tags: Vasoconstriction
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