2.85 Reflex arc

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

Source: http://content.answcdn.com/main/content/img/oxford/Oxford_Sports/0199210896.reflex-arc.1.jpg

Source: http://moodle.schoolnet.lk/file.php/21/assets/images/ks4/reflex.gif

1. Reflexes are involuntary
- cannot be suppressed
- the reflex arc is the pathway of the impulse along the neurones

2. Stimulus: pain
Receptor: pain receptor in finger
- Impulse travels to the spinal cord along the sensory neurone
- [spinal cord] Impulse is passed on to the relay neurone (connecting the sensory/motor without going to the brain // quicker time) and to the motor neurone
- Effector: Muscle
Response: Withdrawal of hand

3. Number of synapses
- one between each neurone; three