Efferent Vs Afferent

Peripheral nerves (PNS) 

• 31 pairs 
• Contains sensory, motor, and autonomic neurons 
• Most PNS have a ventral root (efferent[motor]) and dorsal root (afferent[sensory]) component 
• This is the basic of a reflex since it does not reach the brain to be process only a reactions to the spinal cord 
• Simple anatomy terms:
  • Axon
    • = part of the nerve where impulses travel away 
  • Dendrites
    • = Area of nerve where impulses are received  
  • Motor unit
    • = all of the muscles innervated by this nerve 
  • Myelin
    • = lipid sheaths that protect neuro-pathways and increase conductivity 
  • Nerve conduction velocity
    • = speed of nerve impulse 
  • Neruons
    • ​​​​​​​= Nerves basically 
  • Nodes of ranvier
    • = a gap between nerves of nerves to tissues where impulses jumps to the next 
  • Saltatory conduction
    • = the action potential when jumping from node to node where decrease salts = increase conductivity 
  • Schwann cells
    • = form of myelin that is only in the PNS
• Types of fibers
  •  A fibers 
    • Large fibers 
    • Highly myelinated 
    • High conductivity 
  • B Fibers 
    • Medium fibers 
    • Reasonable myelination 
    • Reasonable conductivity 
  • C Fibers 
    • Small fibers 
    • Low myelination 
    • Low conductivity