Changes

==Key Stage 4==

===Meaning===

===About the Reflex Arc===

: Sometimes a change in the environment is so dangerous it would cause more damage to have to think about it before reacting to it. This is the case for very high [[temperature]]s. If the [[skin]] begins to burn this will cause more damage the longer it takes to react. [[Animal]]s have [[evolution|evolved]] reflex reactions to react quickly to prevent unnecessary damage.

: The [[Impulse (Biology)|impulse]] in the '''reflex arc''' does not pass to the [[brain]] to be processed. It is sent to the [[Spinal Cord|spinal cord]] then to an [[effector]]. This provides a shorter path for the [[Impulse (Biology)|impulse]] so results in a shorter reaction time.

The '''reflex arc''' can be [[describe]]d in several stages:

#[[Motor Neuron]] - The [[Impulse (Biology)|impulse]] is [[transmit]]ted from the [[Spinal Cord|spinal cord]] to an [[effector]].

#[[Effector]] - A [[muscle]] receives the [[Impulse (Biology)|impulse]] form the [[Motor Neuron|motor neuron]].

{| class="wikitable"

| style="height:20px; width:200px; text-align:center;" |A [[diagram]] showing the '''reflex arc'''.

|}