Visceral reflex arcs and somatic reflex arcs differ in the end point of the arc: Visceral reflex arcs end at involuntary muscles and glands, and somatic reflex arcs end at voluntary skeletal muscles. Both reflex arcs go from sensory nerves to their endpoints through the central nervous system.
A reflex is a relatively quick and predictable motor response to a stimulus. This response occurs each time the same stimulus occurs. There are two types of reflexes. Intrinsic reflexes are untrained and are developed along with the development of an organism's nervous system. Their original form is unlearned, but they can sometimes be modified through experience. These are relatively simple reflexes, and occur in both the visceral and somatic reflex arcs.
Acquired reflexes are learned reflexes such as those involved in riding a bike or driving a car. They generally involve somatic reflexes, not visceral reflexes. These reflexes are learned through practice or repetition. Both the triggering stimuli and the response can be far more complex than those of the visceral reflexes. Despite their learned nature, they are still considered reflexes because they can occur without consciously thinking of each movement. They still rely on reflex arcs, with stimuli being transmitted to the central nervous system where they are processed, after which motor signals are automatically sent to the muscles.