Final answer:
The autonomic nervous system is part of the nervous system controlling involuntary functions and includes two subdivisions: the sympathetic and parasympathetic systems. It is not under voluntary control and operates through two sets of neurons in a series to communicate with internal organs.
Step-by-step explanation:
The autonomic nervous system (ANS) is a component of the nervous system that controls involuntary functions such as heart rate, digestion, and respiratory rate. This system is distinguished from the somatic nervous system, which enables voluntary control of skeletal muscles. Unlike the somatic nervous system, the ANS is responsible for involuntary body functions and operates automatically, without conscious intervention. Structurally, the ANS includes two main subdivisions: sympathetic and parasympathetic nervous systems, often working in opposition to maintain homeostasis.
Functionally, it consists of sensory and motor neurons that communicate between the central nervous system and the internal organs. Signaling to internal organs involves a pathway with two sets of neurons in series - a preganglionic neuron and a postganglionic neuron that synapse in autonomic ganglia. The ANS is essential for directing vital functions and is not consciously controlled, and does not directly stimulate skeletal muscle contractions, nor is it involved in problem-solving tasks that are conscious and deliberate actions.