Note: Heat rate and blood pressure The following is asking you to understand the

Question

Note: Heat rate and blood pressure The following is asking you to understand the autonomic and pressure related factors underlying the affects you measured in the pracs. The questions seem theoretical in nature and indeed they are, so your lecture notes and text books will help, but I also encourage you to reflect on how these events were active in regulating heart rate and blood pressure during the activities in the pracs Q1. (4 Marks) Briefly, (2 very brief sentences max!) describe how the sympathetic and parasympathetic nervous systems alter the rate of SA node depolarisation.

Explanation / Answer

1) Stimulation of sympathetic nervous system releases norepinephrine. This increases pacemaker (SA node) rate by decreasing gK+and increasing slow inward gCa++and gNa+; the pacemaker current (If) is enhanced. Stimulation of parasympathetic nervous system releases acetylcholine which has exactly the opposite effects and decreases the rate of depolarisation of SA node.

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