Question

Describe how the schwann cells form the myelin sheath

Answer 1

Schwann cells form the myelin sheath by wrapping their membrane around an axon segment in the PNS, creating a lipid-rich layer that facilitates rapid transmission of electrical signals. This insulation ensures efficient nerve impulse conduction with nodes of Ranvier allowing impulses to travel quickly by 'jumping' from gap to gap.

Step-by-step explanation:

Schwann cells are a type of glial cell responsible for the production of the myelin sheath around axons in the peripheral nervous system (PNS). During the process of myelination, a Schwann cell envelops an axon segment by wrapping its cell membrane around the axon multiple times. This wrapping forms a lipid-rich layer with very little cytoplasm between the layers, effectively insulating the axon and aiding in the rapid transmission of nerve impulses.

The myelin sheath's appearance has been compared to a pastry wrapped around a hot dog, with the sausage representing the axon and the pastry the myelin layers. Unlike oligodendrocytes in the central nervous system (CNS), which can myelinate several axons at once, a single Schwann cell myelinates just one segment of a peripheral nerve. Myelin is not only comprised of the phospholipids from the Schwann cell membrane but also includes proteins that help maintain the structure of the sheath, supporting fast electrical signaling along the nerve fiber.

The role of Schwann cells and myelin is crucial as they contribute to the formation of nodes of Ranvier—regularly spaced gaps in the myelin sheath that allow for saltatory conduction, wherein nerve impulses 'jump' from node to node, drastically increasing the speed at which they travel down the axon.

Answer 2

Step-by-step explanation:

The myelin sheath, lipoprotein structure deposited around axons selected in inner nodules, interrupted periodically by Ranvier nodules, allows saltatory, rapid and effective conduction in the nervous system of vertebrates. The cells that construct myelin are the oligodendrocyte in the nervous central nervous system (CNS) and the Schwann cells in the peripheral nervous system. An oligonucleotide myelinates one or more axons, while the Schwann always forms a single myelin internodule. The process of myelination begins when a cell-sheath projection involves the axon and a loose spiral shape around it. Over time the formed layers are compacted by the expulsion of the cytoplasm and the formation of a lamellar structure with thick electrodes bands - derived from the apposition of the cytoplasmic phases of the membranes - and fewer electrodes - derived of the external phases of the membranes.