16.7
Tejido nervioso: Células Glía
La glía, o neuroglia, son células de apoyo vitales que ayudan a las neuronas en sus funciones. El término "glía" proviene de la palabra griega que sig…
Las células gliales o neuroglía son células no neuronales del sistema nervioso que superan en número a las neuronas. Estos incluyen astrocitos, oligodendrocitos, microglía y células ependimarias en el SNC, y células satélite y de Schwann en el SNP.
Los astrocitos son células en forma de estrella con procesos citoplasmáticos que entran en contacto con las neuronas, los capilares y la piamadre, la cubierta del cerebro y la médula espinal.
Los astrocitos apoyan a las neuronas, ayudan a formar la barrera hematoencefálica, regulan la concentración de iones, como el K+, y reciclan los neurotransmisores liberados.
Los oligodendrocitos tienen procesos citoplasmáticos planos que se envuelven alrededor de los axones, produciendo mielina, que protege y aísla eléctricamente los axones.
Las microglías son pequeñas células fagocíticas que eliminan las células muertas y los patógenos del SNC.
Las células ependimarias son células cuboidales o cilíndricas que recubren los ventrículos del SNC y el canal central. Contribuyen a la producción de líquido cefalorraquídeo y controlan su circulación.
En el SNP, las células satélite rodean y sostienen los cuerpos de las células neuronales y regulan su microambiente. Las células de Schwann o neurolemmocitos mielinizan axones periféricos individuales o encierran varios axones no mielinizados. También participan en la regeneración de los axones.
View the full transcript and gain access to JoVE Core videos
Q1: What are glial cells and how do they differ from neurons?
Glial cells, or neuroglia, are non-neuronal support cells that outnumber neurons in the nervous system. The term 'glia' comes from Greek meaning 'glue,' reflecting their role in holding the nervous system together. Unlike neurons, glial cells provide structural support, maintain chemical balance, and assist neurons in their functions rather than transmitting electrical signals.
Q2: What are the main types of glial cells in the central nervous system?
The CNS contains four main glial cell types: astrocytes are star-shaped cells that support neurons and form the blood-brain barrier; oligodendrocytes produce myelin sheaths around axons; microglia are phagocytic cells that remove debris and pathogens; and ependymal cells line the ventricles and produce cerebrospinal fluid.
Q3: How do astrocytes support neuronal function?
Astrocytes contact neurons, capillaries, and the pia mater with their cytoplasmic processes. They regulate ion concentrations like K+, recycle released neurotransmitters, help form the blood-brain barrier, and guide neuronal growth during embryonic development, maintaining the chemical environment neurons need to function properly.
Q4: What is the role of oligodendrocytes in the nervous system?
Oligodendrocytes produce and maintain myelin sheaths around CNS axons. Myelin is a multilayered lipid and protein covering that electrically insulates axons and protects them. Unlike Schwann cells in the PNS, a single oligodendrocyte can myelinate multiple axons, increasing efficiency of signal transmission.
Q5: What are the differences between Schwann cells and satellite cells in the PNS?
Schwann cells encircle axons and form myelin sheaths, with each Schwann cell myelinating only one axon. They also participate in axon regeneration. Satellite cells, by contrast, surround neuronal cell bodies in PNS ganglia, providing structural support and regulating material exchange between neurons and interstitial fluid.
Q6: How do microglia contribute to CNS health?
Microglia are small phagocytic cells that function as immune cells within the CNS. They actively remove dead cells, cellular debris, and pathogens from the nervous tissue, maintaining a clean environment essential for proper neuronal function and protecting the brain and spinal cord from infection.
Q7: What functions do ependymal cells perform in the CNS?
Ependymal cells are cuboidal or columnar cells arranged in a single layer that line the brain's ventricles and spinal cord's central canal. They produce cerebrospinal fluid, monitor its circulation, and form the blood-cerebrospinal fluid barrier, protecting the CNS from harmful substances while allowing nutrient delivery.