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Glia are smaller more numerous than neurons.

Astrocytes Oligodendrocyte Schwann cell Microglial cells Radial glial cells

Astrocytes wrap around the presynaptic terminals of a group of functionally related axons. By surrounding a synapse between neurons, an astrocyte shields it from chemicals circulating in the surround. By taking up ions released by axons and then release long them back, it helps synchronize the activity of the axons, enable them to send messages in waves. Guide the formation and elimination of synapses. They remove waste material created when neurons die and control the amount of blood flow to each brain area. During periods of heightened activity in some brain area, it dilate the blood vessels to bring more nutrient into that area.

Oligodendrocyte in brain and spinal cord build myelin sheaths that surround and insulate certain vertebrate axons. It also supply an axon with nutrients necessary for its functioning.

Schwann cells in periphery of the body build myelin sheaths that surround and insulate certain vertebrate axons. It also supply an axon with nutrients necessary for its functioning.

Microfilm act as part of the immune system, removing waste material, viruses, and fungi from the brain. They proliferate after brain damage and in most brain diseases. They also contribute to learning by removing the weakest synapses.

Radial glia guide the migration of neurons and their axons and dendrites during embryonic development. When embryonic all development finishes, most radial glia differentiate into neurons, and smaller number differentiate into astrocyte and oligodendrocyte.

Plasma membrane Most chemicals cannot cross the membrane, but protein channel in the the membrane permit a controlled flow of water, oxygen, sodium, potassium, calcium, chloride, and other important chemicals.

The structure that contains the chromosomes.

Perform metabolic activities It require fuel and oxygen.

The sites that the cells synthesizes new protein molecules. Proteins provide building materials for the cell and facilitate chemical reactions. Some float freely within the cell, but others are attached to the endoplasmic reticulum.

A network of thin tubes that transport newly synthesized proteins to other locations.

Wrap or package substances in vesicles for transport to axon terminal Only in neuron and axon

Provide intercellular transport Only in neuron and axon

Most common One axon and many dendrites.

Rare in humans, found in the mesencephalic nucleus of the 5th cranial nerve.

One axon and one dendrite. Are found in cochlear and vestibular ganglia, retina and olfactory epithelium

Afferent Specialized at one end to be highly sensitive to a particular type or stimulation Bring information into a structure

Efferent It’s soma in the spinal cord, receives excitation through its dendrites and conducts impulses along its axon to a muscle Carries information away from a structure

If a cell’s dendrites and axon are entirely contained with a dingle structure, the cell is an interneuron or intrinsic neuron of that structure.

Dendrites are branching fibers that get narrower near their end. The dendrites’ surface is linked with specialized synaptic receptors, at which the dent rite receives information from other neurons. The greater the surface area of a dent rite, the more information it can receive.

Many dendrites contain dendritic spines, short out growths that increase the surface area available for synapses.

Cell body Nucleus, ribosomes, mitochondria Most of a neuron’s metabolic work occurs here. Like dendrites, soma is covers with synapses on its surface in many neurons.

The axon conveys an impulse toward other neurons, an organ, or a muscle. It can range up to more than a meter in length.