Epämyelinisoiduneet

Epämyelinisoiduneet refers to nerve fibers that lack a myelin sheath. Myelin is a fatty insulating layer that surrounds the axons of many neurons. This sheath is formed by glial cells, specifically Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. The presence of myelin allows for rapid transmission of electrical signals along the axon through a process called saltatory conduction.

In contrast, unmyelinated axons are in direct contact with their surroundings. While they can still conduct nerve impulses, the transmission is significantly slower compared to myelinated axons. This slower conduction speed is due to the continuous propagation of the action potential along the entire length of the axon.

Unmyelinated axons are typically smaller in diameter than myelinated axons. They play crucial roles in transmitting certain types of sensory information, such as pain, temperature, and crude touch. They are also involved in autonomic nervous system functions, like regulating smooth muscle and glandular secretions. Examples of unmyelinated fibers include C fibers, which are responsible for transmitting dull, aching pain and are the most numerous type of nerve fiber in the body. The absence of myelin makes these fibers more vulnerable to damage and disruption.