The heart's autonomic control aims to increase which aspects when stimulated?

The heart's autonomic control aims to increase which aspects when stimulated?

• A. Rate, force of contraction, and coronary blood flow.
• B. Rate only.
• C. Force only.
• D. Coronary constriction rather than dilation.

Answer: (A)

When the autonomic system stimulates the heart, it raises overall cardiac performance to meet higher demands. Nerve impulses releasing norepinephrine target the heart’s beta-1 receptors in the SA and AV nodes, speeding up the pace of pacemaker activity and conduction, so the heart rate climbs. They also increase calcium availability in cardiac muscle cells, strengthening each beat and boosting force of contraction. To support this higher level of activity, the coronary circulation must deliver more blood to supply the myocardium’s greater oxygen and nutrient needs; sympathetic activation promotes dilation of coronary vessels (via beta receptors and local metabolic factors), increasing coronary blood flow. In contrast, parasympathetic stimulation would slow the rate and reduce contractility, with minimal direct impact on coronary flow.

When the autonomic system stimulates the heart, it raises overall cardiac performance to meet higher demands. Nerve impulses releasing norepinephrine target the heart’s beta-1 receptors in the SA and AV nodes, speeding up the pace of pacemaker activity and conduction, so the heart rate climbs. They also increase calcium availability in cardiac muscle cells, strengthening each beat and boosting force of contraction. To support this higher level of activity, the coronary circulation must deliver more blood to supply the myocardium’s greater oxygen and nutrient needs; sympathetic activation promotes dilation of coronary vessels (via beta receptors and local metabolic factors), increasing coronary blood flow. In contrast, parasympathetic stimulation would slow the rate and reduce contractility, with minimal direct impact on coronary flow.