QUESTION: Schwann cells are present in __?
ANS:
- Schwann cells are a type of glial cell that are present in the peripheral nervous system (PNS).
- They are named after their discoverer, Theodor Schwann, a German physiologist.
Specifically, Schwann cells are responsible for the following functions:
- Schwann cells are responsible for the formation of the myelin sheath, a fatty substance that wraps around and insulates nerve fibers. This myelin sheath acts as an electrical insulator, allowing for faster and more efficient conduction of nerve impulses.
- In the PNS, Schwann cells form two distinct types of myelination:
- Myelinating Schwann cells wrap themselves around a single nerve fiber multiple times, forming multiple layers of myelin. The compacted myelin sheath enhances the conduction speed of nerve impulses.
- Non-myelinating Schwann cells ensheath multiple nerve fibers but do not form distinct layers of myelin around each individual fiber. They provide support and guidance for the regrowth of nerve fibers during regeneration.
- When a peripheral nerve fiber is damaged, Schwann cells play a vital role in creating a supportive environment for the regrowth of the injured axons.
- They release growth factors and provide structural guidance to promote axonal regrowth.
- Schwann cells also assist in the exchange of nutrients and waste products between nerve fibers and their surrounding environment.
- Schwann cells are distinct from oligodendrocytes, which are glial cells responsible for myelination in the central nervous system (CNS).
| Schwann Cells | Facts |
| Discovery | · Schwann cells were discovered by the German physiologist Theodor Schwann in the 19th century. |
| Location | · Found exclusively in the peripheral nervous system (PNS) |
| Types | · Schwann cells can form two types of myelination in the PNS: · Myelinating Schwann Cells: Wrap around a single nerve fiber multiple times to form compacted layers of myelin. · Non-myelinating Schwann Cells: Ensheath multiple nerve fibers without forming distinct myelin layers. |
| Myelination | · Schwann cells are responsible for myelinating nerve fibers in the PNS, forming a protective myelin sheath around them. · The myelin sheath enhances the conduction speed of nerve impulses and allows for more efficient communication within the nervous system. |
| Nutrient Exchange | · Schwann cells are involved in the exchange of nutrients and waste products between nerve fibers and their surrounding environment, contributing to the overall health and functioning of the nervous system. |
| Nerve Regeneration | · Schwann cells play a crucial role in nerve regeneration. · They create a supportive environment for the regrowth of damaged nerve fibers in the PNS · They provide structural guidance and releasing growth factors that promote axonal regrowth. |