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Monday, 18 June 2018

FUNCTIONAL UNITS OF THE NERVOUS SYSTEM And NEURON STRUCTURE





FUNCTIONAL UNITS OF THE NERVOUS SYSTEM

Neuron is the functional unit of the nervous system that is a specialized cell. Neurons are specific to produce signals that can be communicate over short to  long distances, from one part of an animal’s body to another. Neurons have two important properties:
(1)Excitability, The ability to respond to stimuli; and (2) Conductivity, the ability to conduct a signal.
Neurons have the three functional types, that are sensory neurons, interneurons, and motor neurons. Sensory (receptor or afferent) neurons
Sensory neurons either act as receptor of stimuli themselves or is activated by receptors (figure a). When the internal or external environments change then it stimulate sensory neurons, which are responsible to send the signals to the major integrating centers where information is processed.
 Interneurons (figure c) consist the integrating centers and receive signals from the sensory neurons and transmit them to motor neurons.
 Motor (effector or efferent) neurons (figure b) that send the processed information  a signal to the body’s effectors (e.g., muscles),that cause  to contract, or to glands, causing them to secrete.

NEURON STRUCTURE

Neurons contain three principal parts: A cell body, dendrites, and an axon.
The cell body has a central, large nucleus. The motor neuron in figure b has many short, thread-like branches called dendrites, which are actually extensions of the cell body that conduct signals toward the cell body. The axon is a long and  cylindrical process that conducts signals (information) away from the cell body.
The nervous system receives data (input stimulus), then integrates it, and effects a change (output response) in the animal’s physiology. In a given neuron, the dendrites are the receptors, the cell body is
the integrator, and the ends of the axon are the effectors.

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