Neuroglial cells—usually referred to simply as glial cells orglia—are quite different from nerve cells. The major distinction is thatglia do not participate directly in synaptic interactions and electrical signaling,although their supportive functions help define synaptic contacts and maintain thesignaling abilities of neurons. Glia are more numerous than nerve cells in thebrain, outnumbering them by a ratio of perhaps 3 to 1. Although glial cells alsohave complex processes extending from their cell bodies, they are generally smallerthan neurons, and they lack axons and dendrites (Figure 1.4). The term glia (from the Greek word meaning“glue”) reflects the nineteenth-century presumption that thesecells held the nervous system together in some way. The word has survived, despitethe lack of any evidence that binding nerve cells together is among the manyfunctions of glial cells. Glial roles that are well-establishedinclude maintaining the ionic milieu of nerve cells, modulating the rate of nervesignal propagation, modulating synaptic action by controlling the uptake ofneurotransmitters, providing a scaffold for some aspects of neural development, andaiding in (or preventing, in some instances) recovery from neural injury.
Neuroglial cells. Tracings of an astrocyte (A), an oligodendrocyte (B),and a microglial cell (C) visualized by impregnation with silver salts.The images are at approximately the same scale. (D) Astrocytes in thebrain labeled with an antibody against (more...)
There are three types of glial cells in the mature central nervous system:astrocytes, oligodendrocytes, and microglial cells (Figure 1.4A—C).Astrocytes, which are restricted to the brain and spinal cord, haveelaborate local processes that give these cells a starlike appearance (hence theprefix “astro”). The major function of astrocytes is tomaintain, in a variety of ways, an appropriate chemical environment for neuronalsignaling. Oligodendrocytes, which are also restricted to the central nervoussystem, lay down a laminated, lipid-rich wrapping called myelin around some, but notall, axons. Myelin has important effects on the speed of action potential conduction(see Chapter 3). In the peripheral nervous system, the cells that elaborate myelin are called Schwann cells. As thename implies, microglial cells are smaller cells derived from hematopoietic stem cells (although some may be derived directly from neural stem cells). They sharemany properties with tissue macrophages, and are primarily scavenger cells thatremove cellular debris from sites of injury or normal cell turnover. Indeed, someneurobiologists prefer to categorize microglia as a type of macrophage. Followingbrain damage, the number of microglia at the site of injury increases dramatically.Some of these cells proliferate from microglia resident in the brain, while otherscome from macrophages that migrate to the injured area from the circulation.
FAQs
Neuroglial cells provide homeostatic support, protection, and defense to the nervous tissue.
What is a Neuroglial cell quizlet? ›
Neuroglial cells. support cells for neurons, nourish neurons, send/receive messages. astrocytes. star shaped, form BBB ( by holding together neurons and blood vessels with a separation into a two layered structure)
What do neuroglial cells make up? ›
(i) Neuroglia makes up more than one-half of the volume of neural tissue in our body. (ii) Neuroglia protects and supports neurons. (iii) When a neuron is suitably stimulated, an electrical disturbance is generated which swiftly travels along its cytosol.
What can neuroglial cells not do? ›
The major distinction is that glia do not participate directly in synaptic interactions and electrical signaling, although their supportive functions help define synaptic contacts and maintain the signaling abilities of neurons.
What is neuroglia function? ›
Neuroglia are sub-classified into CNS and PNS glia, but overall their functions are the same – to provide homeostatic, structural and metabolic support of neurons, to meylinate their axons to ensure rapid signal transmission and to be the main defensive and immunocompetent cells.
What is the neuroglia and its function? ›
Their role is to be the support team and cheerleaders for the neurons. The neuroglia: Form myelin, which wraps around axons to speed up electric impulse conduction. Provide nutrients to your neurons, including oxygen.
What is the neuroglia easy definition? ›
(noor-OH-glee-uh) Any of the cells that hold nerve cells in place and help them work the way they should.
What is neuroglia glial cells? ›
Glial cells, or neuroglia, are cells that surround the neurones of the central nervous system embedded between them, providing both structural and physiological support.[4] There are four main classes of neuroglial cells (see link) within the CNS. Astrocytes.
What is neuroglia neuron? ›
What are Neuroglia? Neuroglia are non-neuronal cells that support and protect the neurons. Neuroglia in the central nervous system include astrocytes, oligodendrocytes, microglial cells, and ependymal cells.
What are some facts about neuroglia? ›
Neuroglia exist in the nervous systems of invertebrates as well as vertebrates and can be distinguished from neurons by their lack of axons and by the presence of only one type of process. In addition, they do not form synapses, and they retain the ability to divide throughout their life span.
Indeed, in the CNS, neuroglia include the cells of the choroid plexus, the oligoden- drocytes, the ependymal cells, the radial glia of the retina, the immunocompetent microglia/innate macrophages and the hugely diverse astrocytes; whereas, in the PNS, they include the diverse kinds of Schwann cells, satellite glia, ...
How do Neuroglial cells support neurons? ›
Glia guide developing neurons to their destinations, buffer ions and chemicals that would otherwise harm neurons, and provide myelin sheaths around axons. Scientists have recently discovered that they also play a role in responding to nerve activity and modulating communication between nerve cells.
What do neuroglial cells protect? ›
Glial (Neuroglial) cells do not conduct nerve impulses, but, instead, support, nourish, and protect the neurons. Glial cells are far more numerous than neurons and, unlike neurons, are capable of mitosis.
Do neuroglial cells have the ability to divide? ›
Glial cells differ from neurons in that they possess no synaptic contacts and retain the ability to divide throughout life, particularly in response to injury. The rough schema represented in Figure 1-3 demonstrates the interrelationships between the macroglia and other CNS components.
What are some functions of neuroglia quizlet? ›
Six functions of neuroglia:
- Maintaining homeostasis.
- Forming myelin and providing support and protection for neurons.
- Detecting sensory receptors.
- Supplying nutrients to the nervous cell.
- Repair of damaged tissue.
- Role in neurotransmittion.
Neuroglial cells are the non-neuronal cells that support and protect the neurons. They do not participate in the conduction of nerve impulses and hence they do not form synapses. They are of 4 types viz., astrocytes, Schwann cells, oligodendrocytes and microglia.
