Final answer:
Long reflexes that originate outside of the digestive system are classified as somatic and visceral reflexes, both of which involve the central nervous system. They are contrasted with short reflexes, which operate locally within the digestive system and do not involve the CNS.
Step-by-step explanation:
Long reflexes that originate completely outside the digestive system include somatic reflexes and visceral reflexes, which are called long reflexes. These reflexes involve afferent branches that enter the spinal cord or brain and efferent branches that carry outputs to their targets. In contrast, short reflexes involve only local integrations of sensory input with motor output within the alimentary canal and are part of the enteric nervous system. They are not mediated by the central nervous system (CNS) and affect digestion locally.
For example, the stimulation of sensory neurons by the sight, smell, and taste of food sends signals to the medulla oblongata initiating long reflexes that stimulate stomach cells to secrete digestive juices. This is different from short reflexes, such as when food distends the stomach and local reflexes cause stomach cells to increase secretion of digestive juices.