Just wondering...

Hmm...last night I was thinking...your receptors react to stimuli, which travel along your sensory neurons, which transmit the information to the CNS, which then sends the response via motor neurons to the effectors which are either muscles/glands. I was wondering, the more sensitive an area is, does that mean there are more receptors, or is it just that the receptors are just trained to be more sensitive? Just wondering...