glial cell

(noun)

Non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the central nervous system and peripheral nervous system.

Related Terms

  • nodes of Ranvier
  • myelination
  • glia
  • myelin
  • blood-brain barrier
  • nodes of ranvier
  • neurotransmitter
  • synapse

(noun)

Non-neuronal cells that provide structure and support to neurons.

Related Terms

  • nodes of Ranvier
  • myelination
  • glia
  • myelin
  • blood-brain barrier
  • nodes of ranvier
  • neurotransmitter
  • synapse

Examples of glial cell in the following topics:

  • Introducing the Neuron

    • Neurons are specialized cells that transmit chemical and electrical signals.
    • The brain is made up entirely of neurons and glial cells, which are non-neuronal cells that provide structure and support for the neurons.
    • The cell body contains a specialized structure, the axon hillock, which serves as a junction between the cell body and the axon.
    • Myelin is produced by glial cells (or simply glia, or "glue" in Greek), which are non-neuronal cells that provide support for the nervous system.
    • In the central nervous system, the glial cells that form the myelin sheath are called oligodendrocytes; in the peripheral nervous system, they are called Schwann cells.
  • Cerebral Cortex

    • It contains glial cells, which guide neural connections, provide nutrients and myelin to neurons, and absorb extra ions and neurotransmitters.
    • Gray matter is the mass of all the cell bodies, dendrites, and synapses of neurons interlaced with one another, while white matter consists of the long, myelin-coated axons of those neurons connecting masses of gray matter to each other.
  • Neurotransmitters

    • Neurotransmitters are chemicals that transmit signals from a neuron across a synapse to a target cell.
    • Neurotransmitters are chemicals that transmit signals from a neuron to a target cell across a synapse.
    • A neuron has a negative charge inside the cell membrane relative to the outside of the cell membrane; when stimulation occurs and the neuron reaches the threshold of excitement this polarity is reversed.
    • When the chemical message reaches the axon terminal, channels in the postsynaptic cell membrane open up to receive neurotransmitters from vesicles in the presynaptic cell.
    • A pump in the cell membrane of the presynaptic element, or sometimes a neighboring glial cell, clears the amino acid from the synaptic cleft so that it can be recycled, repackaged in vesicles, and released again.
  • Cognitive Development in Childhood

    • Once nerve cells in the brain are in place, they form synapses.
    • Glial cells, which account for half of all brain mass in early childhood, are responsible for a process known as myelination.
    • Synapses, or the spaces between nerve cells, develop rapidly during childhood.
  • Mechanics of the Action Potential

    • It is not a physical component of a cell but rather a name for the gap between two cells: the presynaptic cell (giving the signal) and the postsynaptic cell (receiving the signal).
    • During a chemical reaction, a chemical called a neurotransmitter is released from one cell into another in an electrical reaction, the electrical charge of one cell is influenced by the charge an adjacent cell.
    • Presynaptic cell: a specialized area within the axon of the giving cell that transmits information to the dendrite of the receiving cell.
    • Postsynaptic cell: a specialized area within the dendrite of the receiving cell that contains receptors designed to process neurotransmitters.
    • During the refractory phase this particular area of the nerve cell membrane cannot be depolarized; the cell cannot be excited.
  • Gustation: Taste Buds and Taste

    • Each taste bud is flask-like in shape and formed by two types of cells: supporting cells and gustatory cells.
    • Gustatory cells are short-lived and are continuously regenerating.
    • An ion channel in the taste cell wall allows Na+ ions to enter the cell.
    • This depolarizes the cell and floods it with ions, leading to a neurotransmitter release.
    • The third allows sodium ions to flow down the concentration gradient into the cell.
  • The Role of Genes in Prenatal Development

    • Every person is made up of cells, each of which contains chromosomes.
    • Gene regulation is the process by which cells differentiate.
    • Among other things, it is the process in which a cell determines which genes it will express and when.
    • Cell differentiation is a process by which a less specialized cell becomes a more specialized cell.
    • For example, as a zygote develops, gene regulation changes some cells into brain cells and others into liver cells.
  • Prenatal Brain Development

    • A zygote begins as a one-cell structure that is created when a sperm and egg merge.
    • During the first week after conception, the zygote rapidly divides and multiplies, going from a one-cell structure to two cells, then four cells, then eight cells, and so on.
    • This process of cell division is called mitosis.
    • After 5 days of mitosis there are 100 cells, and after 9 months there are billions of cells.
    • As the cells divide, they become more specialized, forming different organs and body parts.
  • Stages of the Action Potential

    • Neural impulses occur when a stimulus depolarizes a cell membrane, prompting an action potential which sends an "all or nothing" signal.
    • The sensory input stage is when the neurons (or excitable nerve cells) of the sensory organs are excited electrically.
    • Depolarization, also referred to as the "upswing," is caused when positively charged sodium ions rush into a nerve cell.
    • During the refractory phase this particular area of the nerve cell membrane cannot be depolarized.
    • Damage to the myelin sheath from disease can cause severe impairment of nerve-cell function.
  • Neural Networks

    • If a stimulus creates a strong enough input signal in a nerve cell, the neuron sends an action potential and transmits this signal along its axon.
    • The axon of a nerve cell is responsible for transmitting information over a relatively long distance, and so most neural pathways are made up of axons.
    • The basic neuronal function of sending signals to other cells includes the capability for neurons to exchange signals with each other.
    • In 1949, neuroscientist Donald Hebb proposed that simultaneous activation of cells leads to pronounced increase in synaptic strength between those cells, a theory that is widely accepted today.
    • Cell assembly, or Hebbian theory, asserts that "cells that fire together wire together," meaning neural networks can be created through associative experience and learning.
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