This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous system, Subject name: Physiology
Thickening of axon leads to 
Select and explain. 
A. Increased speed of conduction, B. Decreased speed of conduction, C. Increased absolute refractory period, D. Unmyelination
A: Increased speed of conduction
Answer: A: Increased speed of conduction 
Explanation: Thickening of axon leads to increased speed of conduction as the action potential velocity increases propoionately with axon diameter. Ref: guyton and hall textbook of medical physiology 12 edition page number:76,77,78