The control of K + levels in the brain.
An early recognized function of astrocytes is the control of K + levels in the brain. Neuronal activity leads to an increase in K + concentration from a resting level of about 3 mM to a maximum of 10 - 12 mM under physiological conditions and to even higher values under pathological conditions. Astrocytes may also limit the number of synapses since astrocyte membranes can ensheath the neuronal processes and thus compete with synapses. Astroglial cells can also be involved in the elimination of synapses in the CNS, the process which underlies the final tuning and plasticity of the neuronal inputs. Astrocytes (literally ‘star-like cells’) are the most numerous and diverse neuroglial cells in the CNS. While most neuroscientists think they know what an astrocyte is, there is no uniform and unequivocal definition of an astrocyte. Not all astrocytes are star-like cells, not all of them express the specific marker glial fibrillary acidic protein (GFAP), not all contact brain capillaries. Astrocytes are actually the cell population in the brain which are left over after one would remove neurons, oligodendrocytes and microglial cells. Astrocytes may also limit the number of synapses since astrocyte membranes can ensheath the neuronal processes and thus compete with synapses. Astroglial cells can also be involved in the elimination of synapses in the CNS, the process which underlies the final tuning and plasticity of the neuronal inputs. Astrocytes (Astro from Greek astron = star and cyte from Greek kyttaron = cell), also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord. The proportion of astrocytes in the brain is not well defined. Depending on the counting technique used, studies have found that the astrocyte proportion varies by region and ranges from 20% to 40% of all glia. 1 Structural: They are involved in the physical structuring of the brain. 2  Astrocytes get their name because they are star-shaped. 3  They are the most abundant glial cells in the brain that are closely associated with neuronal synapses. Astrocytes are the most numerous cell type within the central nervous system (CNS) and perform a variety of tasks, from axon guidance and synaptic support, to the control of the blood brain barrier and blood flow. To perform these roles, there is a great variety of astrocytes. In this review, we summarize the function of astrocytes, in particular, their role in maintaining homeostasis at the synapse, regulating neuronal signaling, protecting neurons from oxidative damage, and determining the fate of endogenous neural precursors. Astrocytes-structure/function. A. Characteristics of normal astrocytes. Astrocytes have many cytoplasmic processes that terminate on blood vessels, neuronal cell bodies, axons and synaptic terminals. Astrocytes are a special kind of stellate-shaped brain cells that are found throughout the central nervous system and that play a supportive role for neurons. 1 Other regulatory functions of astrocytes include limiting the rise of both extracellular potassium (K+) and pH during neural activity. 2  In addition, astrocytes can take up potassium in a variety of ways: Na+-K+ exchange, K+-Cl-cotransport and other K+ channels characterized by distinct properties. The dark 'star-like' figures are the astrocytes. Astrocytes are star shaped glial cells that perform a variety of functions in the CNS. Astrocytes provide physical support to neurons and clean up debris within the brain. They also provide neurons with some of the chemicals needed for proper functioning and help control the chemical composition of fluid surrounding neurons. In order to provide physical support for neurons astrocytes form a matrix that keep neurons in place. In addition, this matrix serves to isolate synapses. This limits the dispersion of transmitter substances released by terminal buttons; thus aiding in the smooth transmission of neural messages. List: Astrocyte Functions. Astrocytes are a special kind of stellate-shaped brain cells that are found throughout the central nervous system and that play a supportive role for neurons. For a long time, astrocytes were thought of as merely providing “assistance” for neuron function and survival. 1 Other regulatory functions of astrocytes include limiting the rise of both extracellular potassium (K+) and pH during neural activity. 2  In addition, astrocytes can take up potassium in a variety of ways: Na+-K+ exchange, K+-Cl-cotransport and other K+ channels characterized by distinct properties. GFAP immunostain. This picture explains why these cells are called star cells. Astrocytes (star cells) have radially arranged processes. Their cytoplasm contains intermediate filaments composed of a distinct protein, glial fibrillary acidic protein (GFAP) . Antibodies against this protein are routinely used to demonstrate reactive and neoplastic astrocytes.  a star-shaped glial cell (see neuroglia) that is involved in numerous processes (extensions) that run in all directions. The processes that astrocytes are involved in providing structural support for the brain, are responsible for many homeostatic functions, and may isolate receptive surfaces. ASTROCYTE: An astrocyte is one type of glial cell that serves multiple functions. . No related posts.
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what is astrocyte function