Name: glial cells and nervous system support
Uploaded: 2025-10-23T11:49:28.000Z
Duration: 1 min 4 s
Channel: JoVE

As células gliais são as células de suporte nos sistemas nervosos. O sistema nervoso central, ou SNC, contém uma variedade de glias. O tipo o maior e o mais abundante são os astrócitos.Essas células têm muitas funções, uma das quais é ajudar a manter a barreira hematoencefálica. Outro tipo, os oligodendrócitos, com corpos celulares menores e menos processos, formam as bainhas de mielina ao longo do comprimento dos axônios. As células menos numerosas e menores, as microglias, estão envolvidas em processos fagocíticos, envolvendo patógenos e detritos celulares.Além disso, o sistema nervoso periférico, ou SNP, inclui células satélite que circundam os corpos celulares dos neurônios e funcionam como os astrócitos encontrados no SNC. Da mesma forma, as células de Schwann são as células que agem como oligodendrócitos, ajudando a formar bainhas em torno de axônios periféricos. Conforme a pesquisa continua, é claro que as células da glia vão além do que ser simplesmente a cola no sistema nervoso.

Zuchero, J. Bradley e Ben A. Barres. "Glia no desenvolvimento e doença dos mamíferos." Desenvolvimento (Cambridge, Inglaterra) 142, nº 22 (15 de novembro de 2015): 3805–9. [<a href="https://doi.org/10.1242/dev.129304" target="__blank">Fonte</a>]

células da glia

<h4>Visão Geral</h4>
 
 As células da glia são um dos dois principais tipos de células do sistema nervoso. As células da glia incluem astrócitos, oligodendrócitos, microglia e células ependimais no sistema nervoso central, e células satélite e de Schwann no sistema nervoso periférico. Estas células não se comunicam através de sinais elétricos como os neurónios, mas contribuem para praticamente todos os outros aspectos da função do sistema nervoso. Em humanos, o número de células da glia é aproximadamente igual ao número de neurónios no cérebro.
 
 <h4>Células da Glia do Sistema Nervoso Central</h4>
 
 A glia no sistema nervoso central (CNS) inclui astrócitos, oligodendrócitos, microglia e células ependimais. Os astrócitos são o tipo mais abundante de células da glia e são encontrados em padrões organizados e não sobrepostos por todo o cérebro, onde se associam intimamente a neurónios e capilares. Os astrócitos desempenham inúmeros papéis na função cerebral, incluindo regulação do fluxo sanguíneo e processos metabólicos, homeostase de iões e pH sinápticos, e manutenção da barreira hematoencefálica.
 
 Outra célula da glia especializada, o oligodendrócito, forma a bainha de mielina que envolve axónios neuronais no CNS. Os oligodendrócitos estendem processos celulares longos que envolvem axónios várias vezes para formar este revestimento. A bainha de mielina é necessária para a condução adequada da sinalização neuronal e aumenta consideravelmente a velocidade com que essas mensagens viajam.
 
 A microglia—conhecida como os macrófagos do CNS—é o menor tipo de célula da glia e é especializada em fagocitose de agentes patogénicos e detritos. Ela protege o CNS de agentes infecciosos e toxinas e podam as sinapses durante o desenvolvimento. Embora a microglia seja considerada parte das células da glia, ela tem uma origem única e separada em comparação com outros tipos de células da glia. Os astrócitos e oligodendrócitos são produzidos pela glia radial, enquanto que a microglia é originada no saco vitelino e migra para o embrião no início do desenvolvimento embrionário.
 
 Por fim, as células ependimais são células em forma de cubo com saliências semelhantes a cílios que revestem os ventrículos, onde produzem fluido cefalorraquidiano (CSF). As células ependimais formam uma barreira entre o cérebro e o CSF, filtrando substâncias potencialmente prejudiciais. Como os astrócitos e os oligodendrócitos, as células ependimais são originárias da glia radial encontrada perto dos ventrículos laterais.
 
 <h4>Células da Glia do Sistema Nervoso Periférico</h4>
 
 No sistema nervoso periférico (PNS), existem tipos semelhantes, mas distintos, de células da glia. Por exemplo, funções desempenhadas por astrócitos do CNS são realizadas no PNS principalmente por células satélite, células da glia que fornecem estrutura, suporte e nutrientes aos corpos neuronais com os quais se associam. Outra célula da glia do PNS, a célula de Schwann, funciona como os oligodendrócitos do CNS formando uma bainha de mielina em torno de axónios neuronais. Assim como a mielinação no CNS, a mielinação axonal no PNS fornece o isolamento e condutividade necessários para a transmissão adequada de sinais elétricos.
 
 <h4>Importância da Glia na Saúde e na Doença</h4>
 
 As células da glia são protetoras e reguladoras críticas do sistema nervoso. Elas não só mantêm condições homeostáticas e contribuem para a função cerebral rotineira, mas também respondem a lesões, infeções e doenças do sistema nervoso. Além disso, a glia executa funções críticas durante o desenvolvimento embrionário do sistema nervoso. Essas células contribuem até para a remoção de conexões neuronais desnecessárias, um processo chamado poda sináptica. Devido à importância da glia em inúmeros aspectos da função cerebral, defeitos em uma ou mais populações de células da glia podem levar a condições neurológicas graves e debilitantes, incluindo distúrbios no desenvolvimento, doença de Alzheimer, doença de Parkinson, esclerose múltipla e muitos outros.
 
 Durante o desenvolvimento, as células da glia fornecem uma matriz para que os neurónios migrem adequadamente e façam crescer os seus axónios. Mais tarde na vida, traumas ou doenças neurodegenerativas podem causar perda de conexões neuronais que não podem ser regeneradas, levando a um mau funcionamento ou paralisia.

Células da Glia

Visão geral

As células gliais são um dos dois principais tipos de células do sistema nervoso. As células da glia compreendem astrócitos, oligodendrócitos, microglia e ...

Education

JoVE Core

Biology

Biologia

Human Biology

Biologia Humana

Nervous System

Sistema Nervoso

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

Glial Cells

glial cells and nervous system support

Glial cells support the nervous system and work alongside neurons. They are one of the two main cell types in the nervous system. Unlike neurons, glia do not send electrical signals, but they help with nearly every other part of nervous system function. In humans, glial cells are about as numerous as neurons in the brain.

In the central nervous system, glia include astrocytes, oligodendrocytes, microglia, and ependymal cells. Astrocytes are the most common glial cells. They form organized, non-overlapping patterns in the brain and stay close to neurons and capillaries. They help regulate blood flow, support metabolism, maintain ion and pH balance around synapses, and help maintain the blood-brain barrier.

Oligodendrocytes make the myelin sheath in the central nervous system. This sheath wraps around neuronal axons many times and acts as insulation. Myelin helps nerve signals travel correctly and much faster. Microglia are the smallest glial cells and are known as the macrophages of the CNS. They remove pathogens and debris by phagocytosis and also help prune synapses during development. Unlike other glia, microglia come from the yolk sac and enter the embryo early in development.

Ependymal cells are cube-shaped cells with cilia-like projections that line the ventricles. They produce cerebrospinal fluid, or CSF, and form a barrier between the brain and the CSF. This barrier helps filter out harmful substances. Like astrocytes and oligodendrocytes, ependymal cells come from radial glia near the lateral ventricles.

The peripheral nervous system also has glial cells. Satellite cells support the neuronal cell bodies they surround by providing structure, cushioning, and nutrients. Schwann cells do for peripheral axons what oligodendrocytes do in the CNS. They form myelin around axons and help insulation and conductivity for electrical signaling.

Glia are important for health, development, and disease. They protect the nervous system, keep internal conditions stable, and respond to injury, infection, and disease. They also help guide neuron migration and axon growth during embryonic development. Because they help remove extra neuronal connections through synaptic pruning, problems in glial cells can contribute to developmental disorders, Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and other serious conditions. Damage later in life can also lead to lost connections that are difficult or impossible to replace, which may cause impaired function or paralysis.

Glial Cells and Nervous System Support

what is a nervous system?

Nervous System Parts and Control

The nervous system is a network of specialized cells that keeps the body working and helps it respond to the world around it. It controls essential functions such as heart rate and breathing. It also supports movement that helps an organism escape danger. In vertebrates, the nervous system has two major parts: the central nervous system, or CNS, and the peripheral nervous system, or PNS. The CNS includes the brain, spinal cord, and retina, which is the sensory tissue of the visual system. The...

the parasympathetic nervous system

Rest and Digest: Parasympathetic Control

The parasympathetic nervous system helps the body stay calm and return to a rested state. It is one of the two major divisions of the autonomic nervous system, which controls many unconscious functions such as heart rate and digestion. Its neurons are found in the brain and the peripheral nervous system, and they send axons to muscles, organs, and glands. This system is often called the “rest and digest” system because it supports body processes that restore homeostasis. It is most active...

the sympathetic nervous system

Sympathetic Stress Response and Body Changes

The sympathetic nervous system helps the body respond to stress and danger. It is one of the two main divisions of the autonomic nervous system. When it turns on, it prepares the body for action and puts lower-priority functions, such as digestion, on hold. This response is often called the fight-or-flight system. A surprise exam can trigger it, and students may notice a tight stomach, a dry mouth, and a fast heartbeat. In a real threat, the system shifts blood away from the digestive system...

the blood-brain barrier

How the Blood-Brain Barrier Works

The blood-brain barrier is a specialized system of blood vessels that helps control what enters the brain. It delivers nutrients from the blood while tightly regulating ions, molecules, pathogens, and other substances. This semipermeable barrier protects the brain and also makes it harder to deliver some therapies. The blood-brain barrier includes several cellular parts, especially endothelial cells and astrocytes. These cells share a common basement membrane and regulate movement between the...

neuron structure

How Neurons Send Signals

Neurons send signals through a clear set of structures that let them receive, process, and pass on information. They are the main cells of the nervous system and use electrochemical signals to communicate. Neurons also talk to other cells through neurotransmitters at junctions called synapses. Most neurons share three main parts: a cell body, also called the soma, dendrites, and an axon. The soma holds the nucleus and other organelles needed for cell function. Dendrites usually receive...

glial cells

Glial cells support the nervous system and work alongside neurons. They are one of the two main cell types in the nervous system. Unlike neurons, glia do not send electrical signals, but they help with nearly every other part of nervous system function. In humans, glial cells are about as numerous as neurons in the brain. In the central nervous system, glia include astrocytes, oligodendrocytes, microglia, and ependymal cells. Astrocytes are the most common glial cells. They form organized,...

action potentials

How Nerve Signals Travel in Axons

Neurons send signals through action potentials, the rapid electrical changes that move along the axon. These signals lead to neurotransmitter release at axon terminals, which passes information through the nervous system. An action potential is an all-or-none change in membrane potential, the voltage across a cell membrane. A neuron usually has a resting membrane potential of about -70 millivolts. When it receives signals from neurotransmitters or sensory input, the membrane can become more...

the resting membrane potential

How Neurons Keep a Negative Resting Charge

Neurons keep a negative resting charge across their membrane. This electrical difference, called the membrane potential, comes from how ions move and how the membrane lets them pass. In a resting neuron, the inside is typically around -70 millivolts and is more negative than the outside, so the cell is polarized. Two main factors create this resting state. First, the membrane is selectively permeable, which means most ions and molecules cannot cross the lipid bilayer without help from ion...

long-term potentiation

Synaptic Strengthening in Learning and Memory

Long-term potentiation, or LTP, is a form of synaptic strengthening in the brain. It changes the strength of chemical synapses over time between pre- and postsynaptic neurons. LTP works against long-term depression, or LTD, which weakens synapses. Together, LTP and LTD are major mechanisms behind learning and memory. LTP can happen when a presynaptic neuron fires again and again and keeps stimulating a postsynaptic neuron. This is called Hebbian LTP, based on Donald Hebb’s idea that neurons...

long-term depression

Synaptic Pruning in Long-term Depression

Long-term depression, or LTD, is a form of synaptic plasticity that weakens chemical synapses over time. It acts between presynaptic and postsynaptic neurons. LTD works in opposition to long-term potentiation, or LTP, which strengthens synapses. Together, LTD and LTP are two of the main mechanisms behind learning and memory. LTD helps the brain avoid staying locked in a fully strengthened state. If synapses were always maximally strengthened, the brain would become less efficient and it would...

the synapse

How Neurons Signal at Synapses

Neurons communicate through synapses, the points where two neurons meet to pass on signals. At a synapse, the sending neuron is the presynaptic cell, and the receiving neuron is the postsynaptic cell. Most neurons can serve in both roles because they send and receive information. Electrical synapses move signals directly between cells. The presynaptic and postsynaptic cells are linked by gap junctions, which are proteins that physically connect them. This type of synapse can pass electrical...

key terms and concepts

Learn how astrocytes, oligodendrocytes, microglia, ependymal cells, satellite cells, and Schwann cells support neurons in the CNS and PNS.

Glial Cells and Nervous System Support | JoVE K12

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Glial Cells and Nervous System Support

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