Life Sciences P1 Proccesses to remember

A reflex action

A quick, automatic response to a stimulus. Examples: knee-jerk, sneezing and quickly removing a body part away from danger to respond to pain.

A reflex arc

The pathway along which an impulse is transmitted to bring about a response to a stimulus during a reflex action.

Significance of a reflex action

he reflex action allows for a quick response, without thinking about it, to prevent damage to the body.

Significance of a synapse

• It ensures that the impulse moves in only one direction.

• It prevents continuous stimulation of the neurons.

• It ensures that the impulse is transmitted from the sensory neuron to the motor neuron.

The reflex arc of a person touching a sharp pin

1. The stimulus is detected by receptors and converted into a nerve impulse.

2. The nerve impulse is transmitted along the sensory neuron through the dorsal root to the spinal cord.

3. The impulse is transmitted from the sensory neuron to an interneuron in the spinal cord.

4. The impulse is transmitted from the interneuron to a motor neuron in the spinal cord.

5. The impulse exits the spinal cord through the ventral root and is transmitted along the axon of the motor neuron to the effector organs (muscle; this causes the muscles in the limb to contract).

6. The hand pulls away from the stimulus quickly.