Neurons are classified functionally according to the direction the nerve impulse travels relative to the central nervous system (CNS). Afferent neurons are the neurons of the sensory nervous system. They are responsible for conducting sensory input from both somatic sensory and visceral sensory receptors. Most sensory neurons are unipolar. Efferent neurons are the neurons of the motor nervous system, conducting motor output from the CNS to the effectors. All motor neurons are multipolar. Interneurons (or association) neurons lie entirely within the CNS. They receive stimulation from many other neurons and carry out the integrative function of the nervous system. The most numerous types of neurons are interneurons.
Neurons, the fundamental units of the nervous system, are functionally classified based on the direction of the nerve impulse and their role in transmitting information. Afferent neurons, also known as sensory neurons, play a crucial role in the sensory nervous system. These neurons convey sensory input from various receptors, including somatic sensory and visceral sensory receptors, towards the central nervous system (CNS). A characteristic feature of most sensory neurons is their unipolar structure.
Conversely, efferent neurons, components of the motor nervous system, carry motor output signals away from the CNS to the effectors, such as muscles or glands. Motor neurons, a subtype of efferent neurons, are further classified as multipolar, featuring multiple processes extending from the cell body. All motor neurons share the common function of executing responses to stimuli, facilitating muscular contractions or glandular secretions.
Interneurons, also known as association neurons, reside entirely within the CNS. These neurons receive inputs from multiple sources, integrate the information, and contribute to the coordination and processing of signals. Interneurons are crucial for the integrative function of the nervous system, enabling complex information processing and decision-making.
The most abundant neuron type, accounting for the majority in the nervous system, is the interneuron. Their prevalence underscores their essential role in orchestrating the intricate functions of the nervous system.