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PNS Structure - Anatomy & Physiology (view source)

Revision as of 17:27, 23 January 2011

667 bytes removed ,  17:27, 23 January 2011
→‎Connective Tissue
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===Retrograde Transport===
 
===Retrograde Transport===
 
Retrograde transport returns materials from the axon terminal to the cell body, either for degradation or restoration and reuse. As with fast anterograde transport, particles move along microtubules. The motor molecule for retrograde transport is '''dynein''' which is a microtubule-associated ATPase. The retrograde transport system is important not only for returning material to the cell body, but also provides the means whereby target-derived trophic factors, such as nerve growth factor (NGF) for dorsal root ganglion neurons, are conveyed to the cell body where they promote cell survival. Research is being undertaken into the use of trophic factors to promote cell survival during degenerative pathology. The retrograde transport system can be "hijacked" by harmful substances to gain entry to the peripheral neuron and ultimately the CNS. [[Herpesviridae|Herpes simplex virus]], [[Rhabdoviridae|rabies]], [[Tremors and Movement Disorders (Nervous System) - Pathology#Tetanus|tetanus]] and heavy metals all affect the retrograde transport system.
 
Retrograde transport returns materials from the axon terminal to the cell body, either for degradation or restoration and reuse. As with fast anterograde transport, particles move along microtubules. The motor molecule for retrograde transport is '''dynein''' which is a microtubule-associated ATPase. The retrograde transport system is important not only for returning material to the cell body, but also provides the means whereby target-derived trophic factors, such as nerve growth factor (NGF) for dorsal root ganglion neurons, are conveyed to the cell body where they promote cell survival. Research is being undertaken into the use of trophic factors to promote cell survival during degenerative pathology. The retrograde transport system can be "hijacked" by harmful substances to gain entry to the peripheral neuron and ultimately the CNS. [[Herpesviridae|Herpes simplex virus]], [[Rhabdoviridae|rabies]], [[Tremors and Movement Disorders (Nervous System) - Pathology#Tetanus|tetanus]] and heavy metals all affect the retrograde transport system.
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==Connective Tissue==
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Peripheral nerves have a three-tiered hierarchical arrangement of connective tissue. A nerve fibre is surrounded by a connective tissue matrix called the '''endoneurium'''. Bundles, or '''fasicles''' of neurons are enclosed in a second connective tissue layer called the '''perineurium'''. Groups of fascicles are then gathered together in a third connective tissue layer called the '''epineurium'''. Renaut bodies (loose, cigar-shaped whorls of extracellular matrix within fascicles) may be present in some species, particularly in horses. Renaut bodies may also occur in human and rat nerves at points of stress or compression.
   
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