When sympathetic neural control is dominant, what effect does it have on cardiac output?

When sympathetic neural control is dominant, it leads to an increase in cardiac output. The sympathetic nervous system stimulates the heart, enhancing both heart rate and contractility. This means that the heart not only beats faster but also pumps more forcefully, resulting in a greater volume of blood being circulated per minute.

During situations that require quick responses—such as during exercise or moments of stress—the body activates the sympathetic system to ensure that vital organs, particularly muscles and the brain, receive adequate blood flow. This is facilitated by the release of neurotransmitters like norepinephrine, which binds to beta-adrenergic receptors on cardiac cells. The overall effect is an increase in stroke volume, the amount of blood ejected with each heartbeat, as well as an elevation in heart rate, thus boosting cardiac output.

This increase in cardiac output is crucial for meeting the heightened metabolic demands of the body during periods of activity, underlining the importance of sympathetic nervous activity in regulating cardiovascular function.