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Sympathctic

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nerves

Catecholamine output by suprarcnal medul-lae promoted by sympathetic stimulation

Baroreceptors stimulated by hse in blood pressure; fali in blood pressure de creases tonie sympathctic inhibition

Sympathetic nerve stim-ulntion and circulating catecholamines, plus rełative decrease in va* gal tonę, accelerate SA node discharge ratę

Increased ratę of contraction

Skin: vasoconstriction at first. then dilation for heat dissipation

Increased venous return due to action of muscle pump and respiratory movemenls "

Sympathctic nerves and circulating catecholamine dilate coronary arteries iirv crease O 2 supply and mc-tabolite removal) and ad direclly on heart muscle. accelerating myocardial metabolism

Liver and splanchnic beds blood llow diminishes

Increased

Kidneys: blood flow diminishes

Muscle: inilial compression followed by marked vasodilation due to relcase of mctabolites and circulating epinephrine

Figurę 4.21 Circulatory Response to Exercise ___._

This figurp summarizes the integrated neural and Chemical effects of    effects are mediated locally by the release of va$oactive metabf »!■•—

exercise on the cardiovascular system. Neural effects are mediated and the effects of circulating catechołamines (e.g.. epinepłuinc i centrally (by the autonomie nervous system), whereas the Chemical