Regulation of the heart rate, speed of electrical conduction, and strength of contraction are influenced by the brain via which nervous system?

The regulation of the heart rate, speed of electrical conduction, and strength of contraction is indeed influenced by the autonomic nervous system. This system is responsible for involuntary bodily functions, including those that control the heart. The autonomic nervous system has two main branches: the sympathetic and parasympathetic nervous systems.

The sympathetic branch increases heart rate and force of contraction during stressful situations (the "fight or flight" response), while the parasympathetic branch, primarily through the vagus nerve, decreases heart rate during restful states (the "rest and digest" response). This dual regulation allows the body to adapt to varying levels of activity and maintain homeostasis.

In contrast, the central nervous system comprises the brain and spinal cord, which processes information but does not directly regulate heart function in the manner specified in the question. The somatic nervous system primarily controls voluntary movements and reflexes rather than involuntary functions such as heart regulation. The peripheral nervous system encompasses all nerves outside the brain and spinal cord, but it includes both autonomic and somatic divisions; therefore, it does not specifically focus on heart regulation as the autonomic nervous system does.

Thus, the autonomic nervous system is the correct answer as it specifically handles the involuntary