E . Ner vous T i s sue
The nervous system, though quite complex, is composed of tissue that contains only 2 cell types.
i. Neurons
Neurons are sensitive to various stimuli converting it to electrical signals called Action Potentials (nerve impulses). These action potentials are then conducted to other neurons. Most neurons consist of 3 basic parts:
Cell body : contains the nucleus and other organelles.
Dendrites : many highly branched processes that are the major input part of the neuron.
Axon : a single process which is the output portion of the neuron conducting action potentials toward other neurons.
ii. Neuroglia
Make up about 50% of the Central Nervous System (CNS). They do not generate action potentials however serve other important roles. Generally, neuroglia have a support function and can multiply at high rates. There are 6 types: astrocytes, oligodendrocytes, microglia, ependymal cells, Schwann cells, satellite cells.
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