![]() ![]() The brain is composed of the basic units of the cerebral hemispheres, brainstem, and cerebellum. These cells form the substance of the brain, spinal cord, and peripheral nervous system. Myelinated axons conduct nerve impulses faster. Myelin is high in lipid and serves the same purpose as insulation around electrical wires. Larger neurons are covered in a myelin sheath. Schwann cells: these cells provide the myelin that covers neurons in the peripheral nervous system. However, when injury occurs, they become more numerous Microglia: these cells are part of the mononuclear phagocyte system of fixed macrophages in tissues. A single oligodendrocyte can provide myelin for as many as 40 neurons. They produce the myelin that surrounds the axons of myelinated neurons of the CNS. Oligodendroglia: the oligodendroglial cells are small round cells that are most prominent in white matter. ![]() The cytoplasm of astrocytes contains intermediate filaments that are composed of glial fibrillary acidic protein (GFAP) that serves to identify these cells. At least one process either extends to and surrounds a capillary or extends to the overlying pia of the brain. These include:Īstrocytes: these cells in the brain have a small, round nucleus and many very thin processes that radiate from them. There are a variety of cells which support neuronal function. Cells of the Nervous System - Glial Cells Interneurons: these are connectors between neurons in the CNS. Sensory neurons: these afferent neurons conduct impulses from sensory stimuli to the central nervous system. Motor neurons: these efferent neurons extend distally to send nerve impulses to muscles for voluntary movement. Some axons are covered in a sheath of myelin. Axons contain organelles and neurofilaments. At the distal end there is a terminal arborization with synapses to other neurons. Most neurons have a single axon, though some can have more than one.
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