Introduction to Glia Flashcards
Neurons vs. Glial cells
Neurons are specialized cells that transmit electrical and chemical signals in the nervous system. They consist of a cell body, dendrites, and an axon, and are responsible for processing and transmitting information.
Glial cells, or neuroglia, are non-excitable cells that support and protect neurons. They include astrocytes, oligodendrocytes, and microglia in the CNS, and Schwann cells and satellite cells in the PNS.
Types of Glia and Their Lineages
Astrocytes, oligodendrocytes, microglia, Schwann cells, and satellite cells are the main types of glial cells in the nervous system.”
Astrocytes
star-shaped cells that provide structural and metabolic support to neurons. They also help maintain the blood-brain barrier and regulate cerebral blood flow.
Oligodendrocytes
produce myelin in the CNS, which helps to insulate and speed up electrical signals along axons.
Microglia
immune cells in the CNS that protect against pathogens and remove cellular debris.
Schwann cells
produce myelin in the PNS and aid in nerve regeneration.
Satellite cells provide support and regulate the environment for neuronal cell bodies in the PNS.
Wiring vs. Volume Transmission
Wiring transmission involves the direct, point-to-point signaling between neurons through synapses. It is specific and localized, allowing for precise communication between neurons.
Volume transmission involves the release of neurotransmitters or other signaling molecules into the extracellular fluid, allowing for widespread, diffuse signaling throughout the brain. It is less specific and more diffuse than wiring transmission.
Glial Ion Channels
Ion channels in glial cells include voltage-gated ion channels, ligand-gated ion channels, and gap junctions, which allow for the exchange of ions and electrical signals between cells.
Glial cell receptors
Glial cells express a variety of receptors, including neurotransmitter receptors and cytokine receptors, which allow for the detection of chemical signals and the regulation of cellular processes.
Glial water channels
Water channels, or aquaporins, allow for the movement of water across cell membranes in response to osmotic gradients.
Mechanisms of Calcium Wave Propagation in Astrocytes
Calcium waves can be initiated by the release of calcium from intracellular stores or by influx of calcium from extracellular sources.
Calcium waves can propagate through gap junctions, which allow for the diffusion of calcium ions and other small molecules between cells.
Calcium waves can also propagate through the release of gliotransmitters, which can activate receptors on neighboring cells and trigger calcium release.
Functions of Glial Cells
Ion homeostasis: Glial cells help to maintain ion balance in the extracellular space, which is critical for proper neuronal function.
Water homeostasis: Glial cells regulate the movement of water across cell membranes and help to maintain proper hydration of brain tissue.
Neuronal energy supply: Glial cells provide metabolic support to neurons, supplying them with energy in the form of glucose and lactate.
Regulation of cerebral blood
Neurons
Neurons are electrically excitable cells that are able to generate action potentials in response to external stimulation. These action potentials propagate through a network of neurons and are the basis for communication in the nervous system.
Glia
Glia are electrically non-excitable cells that do not generate action potentials. Instead, they provide support and protection for neurons and are critical for proper nervous system function.
