Final answer:
A visceral reflex involves autonomic sensory nerves and is part of the autonomic nervous system, controlling involuntary body functions through a two-step pathway involving preganglionic and postganglionic fibers.
Step-by-step explanation:
A visceral reflex is one that involves signals sent along autonomic sensory nerves. Visceral reflexes are part of the autonomic nervous system which manages involuntary functions of the body. Examples of visceral reflexes include reflexes that control heart rate, digestion, and blood pressure. Unlike somatic reflexes that involve skeletal muscles and typically have an immediate somatic motor response, visceral reflexes involve a two-step pathway:
- The preganglionic fiber emerges from a lateral horn neuron in the spinal cord, or a cranial nucleus neuron in the brain stem, to a ganglion.
- The postganglionic fiber then projects to a target effector such as smooth muscle or a gland.
Somatic reflexes, by contrast, always involve the central nervous system (CNS) even in a monosynaptic reflex, which is the quickest reflex arc involving a sensory neuron and a motor neuron with one synapse.
However, some autonomic or visceral reflexes can bypass the CNS, these are known as short reflexes that are completely peripheral and involve only the local integration of sensory input with motor output.