Närvikude

Nervous tissue is the specialized tissue of the nervous system that enables sensing, processing, and transmitting information. It consists of neurons and glial cells and forms both the central nervous system (CNS) and the peripheral nervous system (PNS).

Neurons are the cells that generate and propagate electrical signals. They have dendrites to receive inputs and an axon to send outputs. Glial cells support neurons by providing nutrients, protection, and structural support, and they also participate in repair and regulation of synaptic function.

Nervous tissue is organized into the CNS, comprising the brain and spinal cord, and the PNS, consisting of peripheral nerves and their networks. In the CNS, tissue presents as gray matter (neuron cell bodies and synapses) and white matter (myelinated axons). The PNS contains bundles of fibers that connect the CNS with muscles, glands, and sensory receptors. Myelination, the insulation of axons, increases conduction speed; it is produced by oligodendrocytes in the CNS and by Schwann cells in the PNS.

Developmentally, nervous tissue arises from the neural tube in early embryogenesis. Regeneration differs by region: the CNS exhibits limited repair after injury due to inhibitory glial responses, while the PNS shows greater regenerative capacity with Schwann cells guiding regrowth. Disorders affecting nervous tissue include neuropathies and demyelinating diseases, which disrupt signal transmission and neural function.