Neuronal Structures: Membranes and Myelin Sheath

Neuronal Membranes

• Thin, cellular membranes covering neurons (dendrites and axons).

• Semipermeable, with channels allowing only specific substances to pass.

Myelin Sheath

• Layer of fat-containing cells encasing and insulating most axons.

• Provided by glial cells.

• Function: Significantly speeds up transmission of nerve impulses.

• Disorders: Multiple Sclerosis (MS) is a degenerative disease where myelin hardens, disrupting information flow and causing symptoms like blurry vision and weakness.

• Evolution: Developed to facilitate rapid information travel over longer distances as brain size increased; unmyelinated axons are poor conductors.