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NBME 21 Answers

nbme21/Block 3/Question#29

A 34-year-old man is evaluated after becoming ...

Number of impulses from carotid baroreceptor: decreased;
Sympathetic efferent activity: increased;
Parasympathetic efferent activity: decreased

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submitted by haldol(6),

BP is low so obviously the body will want to respond by increasing sympathetics and decreasing parasympathetics. since the BP is low, there is less pressure against the wall of the carotid sinus -- meaning less stimulation and fewer impulses. fewer carotid impulses means fewer parasympathetics

pparalpha  Hyotension will lead to decreased arterial pressure and DECREASED stretch. This leads to decreased afferent barcreceptor firing (carotid sinus and aortic arch). This leads to an increase in efferent sympathetic firing and decreased efferent PNS stimulation. This leads to vasoconstriction, increased HR and increased BP. +  
sahusema  The way I remember this, carotid massage slows the heart. So baroreceptor stimulation (more impulses) increases parasympathetic output. +  
cienfuegos  FA 2018 pg 291 has helpful image/description +