Närvikiud

Närvikiud, also known as nerve fibers, are the long, slender extensions of nerve cells (neurons). They are the fundamental units of the nervous system responsible for transmitting electrochemical signals throughout the body. These signals allow for communication between the brain, spinal cord, and the rest of the body, enabling a vast array of functions from sensory perception and motor control to complex cognitive processes.

There are two main types of närvikiud: axons and dendrites. Axons are typically longer and transmit signals away from the neuron's cell body, while dendrites are usually shorter and receive signals from other neurons. Many axons are covered by a myelin sheath, a fatty insulating layer produced by glial cells. This sheath significantly increases the speed at which nerve impulses travel along the fiber. Unmyelinated fibers conduct impulses more slowly.

Närvikiud can be classified based on their diameter, myelination, and the type of information they carry. Sensory närvikiud transmit information from sensory receptors to the central nervous system, while motor närvikiud carry signals from the central nervous system to muscles and glands. Autonomic närvikiud are involved in regulating involuntary bodily functions. Damage to närvikiud can result in a variety of neurological disorders, affecting sensation, movement, and organ function. The regeneration of närvikiud in mammals is limited, making recovery from severe nerve damage often challenging.