BIO202H5 Lecture Notes - Lecture 37: Myelin, Signal Transduction, Peripheral Nervous System
Document Summary
Myelin sheath is produced by schwann cells in the peripheral nervous system. Signal transduction is faster and salutatory in myelinated axons. Action potential spreads quickly through the internodes and slowly through the nodes of ranvier. A single axon can be both myelinated and non-myelinated. Step 1: ions cannot leak out through a myelinated membrane as the charge spreads down the axon. Step 2: charge is spreading without any impediments until it reaches. Nodes of ranvier (it slows down as it reaches the nodes of ranvier, then speeds up after it passes them) Tep 3: sig(cid:374)als co(cid:374)ti(cid:374)ue to (cid:862)ju(cid:373)p(cid:863) dow(cid:374) the axo(cid:374), (cid:373)aki(cid:374)g the sig(cid:374)al transduction much faster. Nerves: groups of axons from neurons organized in fascicles and surrounded by layers of connective tissue (endoneurium, perineurium, and epineurium) and also contain blood vessels. Single neuron is surrounded by an endoneurium that is surrounded by a perineurium, and many fascicles are surrounded by the epineurium (from interior to exterior, endoneurium perineurium.
