Friday, January 27, 2012

2.84 + 2.85 nerve impulses --> responses

Understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses
Describe the structure and functioning of a simple reflex arc illustrated by the withdrawal of a finger from a hot object

1. Reflex actions

when a receptor is stimulated by a change, it sends an electrical impulse along the sensory nerves to the CNS, where the brain co-ordinates the response (decision making). Sometimes a very rapid response is need = reflex actions.

Reflex actions are rapid and happen without us thinking.

eg: pulling your hand away from a hot surface. (you do it without thinking about it)

  • pain receptor detects a stimulus (heat)  
  • sensory nerve sends the electrical impulse to the CNS, brain
  • the motor nerve sends the signal to the effector 
  • the effector (skin) produces a response (reflex +muscle contracts)

No comments:

Post a Comment