EVERYDAY SCIENCE

Detailed explanation-1: -The sympathetic nervous system (SNS) releases the hormones (catecholamines-epinephrine and norepinephrine) to accelerate the heart rate.

Detailed explanation-2: -Exercise stimulates the sympathetic nervous system and will induce an integrated response from the body; This response works to maintain an appropriate level of homeostasis for the increased demand in physical, metabolic, respiratory, and cardiovascular efforts.

Detailed explanation-3: -The principal functions of the heart are regulated by the sympathetic and parasympathetic divisions of the autonomic nervous system. In general, the sympathetic nerves to the heart are facilitatory, whereas the parasympathetic (vagus) nerves are inhibitory.

Detailed explanation-4: -Heart rate is controlled by the activity of the autonomic nervous system: the sympathetic and parasympathetic nervous systems increase and suppress heart rate, respectively. To evaluate the activity of the autonomic nervous system, it is possible to determine heart rate variability using electrocardiography (ECG).

Detailed explanation-5: -The parasympathetic nervous system mainly innervates the SA and AV nodes in the heart. Atrial muscle is also innervated by vagal efferents, whereas the ventricular myocardium is only sparsely innervated by vagal efferents.