QuestionSBA
QuestionChoice
This is incorrect. Sympathetic activation results in the release of noradrenaline. This binds to alpha-1 receptors on endothelial cells to cause vasoconstriction. Noradrenaline also binds to beta-2 receptors which results in vasodilation, however, the binding to beta-2 receptors is weaker than to alpha-1 receptors. The overall effect is therefore vasoconstriction in response to sympathetic activation.
10026296
b
Binding of noradrenaline from sympathetic fibres to alpha-1 receptors outweighs the binding to beta-2 receptors, resulting in vasodilation
QuestionChoice
This is correct. Sympathetic activation results in the release of noradrenaline. This binds to alpha-1 receptors on endothelial cells to cause vasoconstriction. Noradrenaline also binds to beta-2 receptors which results in vasodilation, however, the binding to beta-2 receptors is weaker than to alpha-1 receptors. The overall effect is therefore vasoconstriction in response to sympathetic activation.
10026295
a
Binding of noradrenaline from sympathetic fibres to alpha-1 receptors outweighs the binding to beta-2 receptors, resulting in vasoconstriction
QuestionChoice
This is incorrect as it is the binding to alpha-1 receptors which causes vasoconstriction whereas binding to beta-2 receptors causes vasodilation. Hence, binding to alpha-1 must outweigh binding to beta-2 to give vasoconstriction overall.
10026297
c
Binding of noradrenaline from sympathetic fibres to beta-2 receptors outweighs the binding to alpha-1 receptors, resulting in vasoconstriction
QuestionChoice
This is incorrect. Sympathetic activation results in the release of noradrenaline. This binds to alpha-1 receptors on endothelial cells to cause vasoconstriction. Noradrenaline also binds to beta-2 receptors which results in vasodilation, however, the binding to beta-2 receptors is weaker than to alpha-1 receptors. The overall effect is therefore vasoconstriction in response to sympathetic activation.
10026298
d
Binding of noradrenaline from sympathetic fibres to beta-2 receptors outweighs the binding to alpha-1 receptors, resulting in vasodilation
QuestionChoice
This is incorrect as noradrenaline is the neurotransmitter released from sympathetic fibres, not acetylcholine.
10026299
e
Binding of acetylcholine from sympathetic fibres to alpha-1 receptors outweighs the binding to beta-2 receptors, resulting in vasoconstriction
Concept
Chapter
2693
3809
Structure and physiology of blood vessels
Topic
159
Cardiovascular physiology
17657
Which of the following is the correct explanation for how sympathetic activation affects blood vessel tone?
a