Nerve vs Neuron
The animals, unlike plants, have developed special systems to respond to the stimuli of the external environment and create changes within the body. The immediate, necessary changes are done by the electric signals of the nervous system, and the long term chemical changes are mediated by the endocrine system. The nervous system consists of the central nervous system (CNS) comprising of the brain and the spinal cord, and the peripheral nervous system coursing outside the central nervous system. All sensory information in multicellular animals is detected by sensory cells. This sensory information is passed on to the effector cells producing the response.
Interposed between the receptors and effectors are the conductile cells of the nervous system, the neurons. These are the basic structural and functional units of the nervous system and ramify throughout an organism, forming an elaborate communication network. A neuron is composed of a cell body, dendrites and an axon. There are three basic types of neurons: pseudounipolar neurons perform a sensory function, bipolar nerve cells situated within the CNS transfers the signals either to a motor neuron or to the brain, and the multipolar neuron is a motor neuron associated in transmitting a response signal on to a muscle or within the CNS.
A nerve, on the other hand, is a bundle of axons or dendrites wrapped in connective tissue that conveys impulses between the central nervous system and some other parts of the body. A typical nerve has a tough outer covering, epineurium. Inside are the long fibrous axons or dendrites of individual neurons, gathered into bundles called fascicles, wrapped in the perinurium. Each axon within these bundles is further wrapped by a myelin sheath formed by Schwann cells, to keep the nervous impulses insulated. Most large nerves are mixed nerves, containing both motor and sensory nerve fibers running to and from a particular region of the body.
What is the difference between Nerves and Neurons?
A nerve is essentially a collection of axon bundles found in the peripheral nervous system. The axons are wrapped in three layers connective tissue for protection and insulation. A neuron, on the other hand, has only one axon, it may be branched and extend in more than one direction. The myelin sheath is found in both nerves and neurons. The neurons are single nerve cells where as nerves are elongated congregations of tissues. The neurons are found in the central and the peripheral nervous system, but the nerves are only in the peripheral nervous system. The neurons are grouped according to the number of extensions that extend from the neuron’s cell body and by the direction that they send information. But the nerves are grouped by the place of their origin in the central nervous system or their destination. It is the single neuron that transmit the action potential of a stimulus or the replying motor signal along the axons dendrites and the cell body whereas, the nerves simply covey the axons to and from the CNS.
The neurons are the oldest cells of the body. Most neurons are never regenerated. The nerves formed to carry their projections along the body are hence composing of many connective tissues for protection. Since nerve cells are always occupied with the function of signal transferring, the neruroglial cells help them perform many housekeeping functions, provide nutrition and absorbs waste products. Any physical damage to the nerves or the neurons can cause pain, loss of sensation, or loss of muscle control. Also, vitamin deficiency, toxins, heavy metals and infectious diseases such as leprosy meningitis and shingles can cause degeneration in neural tissue and even death.