Nervous system in the human body is vitally required for various activities .it enables human body to respond to stimuli in less than a few milliseconds. The transmission of information back and forth the brain and different parts of the body make use of the working of transmission of electrical signals through chemical messengers. The neurons are regarded as the building blocks of the nervous system. They enable different parts of the body to function differently in accordance with the stimulus.
The neurons are a few trillion in number and their network constitutes the nerves and the nervous system. They are similar to the rest of our body cells except that they also specialize in information transfer.
Neurons are differentiated based on their assigned tasks in the human body. The neurons transmitting information from the brain to muscles are known as motor neurons. Those carrying signals from different sensory cells to the brain are referred to as sensory neurons. Those which transmit information amongst neurons in the body are called inter neurons.
Motor neurons control muscular contraction and relaxation which is called movement. These are also known as moto-neurons or efferent neurons. These neurons transmit information from the central nervous system (CNS) to other systems in the body and to muscles too. The sensory neurons carry stimuli from the tissues and sensors in different parts of the body like eyes or skin to the CNS.
These neurons have a special design for their functioning. Each neuron is comprised of 3 essential parts; dendrites, cell body or soma, and axon. Dendrites have receptors which receive information in the form of electrical signal from other neurons or sensory cells which is transmitted in to the cell body. It travels through and reaches the axon. Each axon pushes out a neurotransmitter which transfers the signal to the receptor of the adjacent neuron and retracts the transmitter for reuse.
Somatic motor neurons are involved in the locomotive activity by causing the contraction of the skeletal muscles. Special visceral motor neurons are responsible for enabling movement of our facial muscles and neck. General visceral motor neurons are responsible for contraction of involuntary muscles of the heart, arteries and other viscera. These neurons have slight variation in functioning in vertebrates and invertebrates. In the former, they are responsible only for the contraction of muscles while in the later, they are responsible for both contraction and relaxation.
Improper functioning of these neurons can cause motor neuron disease, also called amyotrophic lateral sclerosis, which is incurable and cause for which is still unknown.
More Articles :
- Function Of Motor Neurons
- How Do Neurons Convey Information ?
- How Many Neurons Are In Brain ?
- The Difference Between Neurons And Neurotransmitters
WiseGeek: What Is A Motor Neuron?