2.90 - Simple Reflex Arc

Edexcel IGCSE Biology

what is a reflex response?

what is a reflex response?

• involuntary response

• does not involve the concious part of the brain as the coordinator of the reaction

• automatic and rapid

why do we need a reflex response?

minimise damage to the body and aids survival

what is the reflex arc?

• pathway of a reflex response taken by electrical impules travelling on neurones

describe the reflex arc

1. the stimulus is detected by the receptor

2. a sensory neurone sends electrical impulses to the spinal cord (coordinator)

3. an electrical impulse is passed to relay neurone in the CNS

4. the relay neurone synapses with a motor neurone

5. motor neurone carries impulse to effector (e.g. muscle)

6. muscle will contract and move away from stimulus (response)

types of neurone