What are afferent and efferent neurons and inter neurons?

Answer 1

These neurons are classified by the direction in which they send their messages. Afferent neurons are typically sensory neurons--neurons which send information to the brain and spine. They send information about the body and immediate environment. Efferent neurons are typically motor neurons, sending information from the brain and spine to the rest of the body. They allow the main control system a way to act on the body. Another way to distinguish these two is to think of afferent nerves as 'approaching' the brain (A) and efferent nerves as 'exiting' the brain (E). Interneurons are relay neurons and their signals, connecting efferent and afferent neurons in network. They can link up the same types or different types of neurons, meaning connecting sensory neurons together, motor neurons together, or the different types together. The simplest example of these three types working in unison is a reflex arc (which is what is activated when you hurt yourself, like stepping on a pin or burning your hand). The sensory/afferent neuron detects pain and signals the interneuron. Simultaneously, the interneuron sends a signal to your efferent/motor neurons to retract your hand/leg/whatever, while also sending a message to the brain. This is why you pull back before you feel pain :).