Neurons
Nervous tissue is highly specialized to use modifications in membrane electrical potentials to relay signals through the body. The impulse conducting cells are called neurons, and they are maintained structurally and metabolically by a variety of support cells, termed glial cells. Neurons have four functional compartments: the cell body, dendrites, axon and presynaptic terminals. 400x
Cell body >
The cell body (soma, perikaryon) of a neuron houses the nucleus and is the major synthetic region of the neuron. The nucleus of most nerve cells is large and very euchromatic, reflecting the intense activity of these cells. One, two or numerous processes are attached to the cell body.
Dendrites >
Most neurons have multiple dendrites, which have a cytoplasm similar to that of the cell body. Dendrites are usually short and branch frequently, tapering as they do so. The large surface area of dendrites enables them to make synaptic contact with numerous axon terminals. Dendrites transmit impulses toward the cell body.
Axon >
Most neurons have a single axon that maintains a fairly uniform diameter. At its termination, the axon branches, forming a terminal arborization. Axons originate from a specialized region of the cell body called the axon hillock and are usually longer than dendrites. Axons transmit impulses away from the cell body.
Axon hillock
Most neurons have a single axon that maintains a fairly uniform diameter. At its termination, the axon branches, forming a terminal arborization. Axons originate from a specialized region of the cell body called the axon hillock and are usually longer than dendrites. Axons transmit impulses away from the cell body.
Presynaptic terminals (boutons) >
The terminal branches of axons end in small button-like structures called presynaptic terminals or terminal boutons. These terminals contain neurotransmitter vesicles, which are released to stimulate the next neuron, a muscle cell or a gland.
