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Grey matter, or gray matter in American English, is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries.
The neocortex is the most developed in its organisation and number of layers, of the cerebral tissues. [5] The neocortex consists of the grey matter, or neuronal cell bodies and unmyelinated fibers, surrounding the deeper white matter (myelinated axons) in the cerebrum. This is a very thin layer though, about 2–4 mm thick. [6]
There are many small variations in the secondary and tertiary folds. [20] The outer part of the cerebrum is the cerebral cortex, made up of grey matter arranged in layers. It is 2 to 4 millimetres (0.079 to 0.157 in) thick, and deeply folded to give a convoluted appearance. [21] Beneath the cortex is the cerebral white matter.
Tangential growth suggests that the grey matter grows at a faster rate than the inner white matter and that the growth rate of the grey matter determines the growth rate of the white matter. Though both methods are differential, with the cortex growing more rapidly than the subcortex, tangential growth has been suggested as a more plausible model.
White matter is composed of bundles, which connect various grey matter areas (the locations of nerve cell bodies) of the brain to each other, and carry nerve impulses between neurons. Myelin acts as an insulator, which allows electrical signals to jump , rather than coursing through the axon, increasing the speed of transmission of all nerve ...
The following diagram is provided as an overview of and topical guide to the human nervous system: Human nervous system. Human nervous system – the part of the human body that coordinates a person's voluntary and involuntary actions and transmits signals between different parts of the body.
Nervous tissue, also called neural tissue, is the main tissue component of the nervous system.The nervous system regulates and controls body functions and activity. It consists of two parts: the central nervous system (CNS) comprising the brain and spinal cord, and the peripheral nervous system (PNS) comprising the branching peripheral nerves.
The most convincing explanation for this is that individual neurons die, leading to the loss of both their cell bodies (i.e. gray matter) and their myelinated axons (i.e. white matter). The gray matter changes can be observed via both gray matter density and gyrification. That the white matter loss is not nearly as clear as that for gray matter ...