Saturday, 23 February 2013

2.86 describe the structure and functioning of a simple reflex arc illustrated by the withdrawal of a finger from a hot object

A reflex is an automatic reaction, for example removing your hand from extreme heat. A reflex arch is the path of the reaction.
It starts at a sense organ e.g a finger;
receptors pick up stimuli e.g heat;
Sensory neurones carry an electrical impulse to the CNS;
A relay neuron carries the impulse through the CNS where a response is decided;
The new impulse is sent through a motor neurone;
This makes an effector carry out a response e.g muscle contracts to bring finger away from heat.

3 comments:

  1. Might be worth noting that the sensory and motor neurone form synapses with the relay neurone

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  2. The Biology Syllabus has changed.... New Syllabus Blog:

    http://igcse-biology-2017.blogspot.hk

    ReplyDelete
  3. more at

    http://igcse-biology-notes.blogspot.hk/2017/06/286-describe-structure-and-functioning.html

    ReplyDelete