Reflex actions

Question 1

What are reflexes?

Answer 1

Automatic responses to stimuli

Question 2

Why are reflexes important?

Answer 2

They you avoid danger or harm because they happen so fast. There are also reflexes that take care of your basic body functions.

Question 3

What neurone’s are involved in reflexes?

Answer 3

1. Sensory neurones
2. Relay neurones
3. Motor neurones

Question 4

What is the reflex arc?

Answer 4

An electrical impulse passes from the receptor along the sensory neurone to the CNS. The impulse then passes along a relay neurone (in the spinal cord) and straight back along the motor neurone until it arrives at the effector organ, which responds. The effector organ will be a muscle or a gland.

Question 5

How do synapses work?

Answer 5

When an impulse arrives at a synapse, molecules are released that cross the gap to receptor sites on the next neurone. This starts up a new electrical impulse in the next neurone.

Question 6

Say what would happen if you touched a hot object as an example of a reflex arc.

Answer 6

1. When you touch the object, a receptor in your skin is stimulated. An electrical impulse from a receptor passes along a sensory neurone to the CNS.
2. When an impulse from the sensory neurone arrives at the synapse with a relay neurone, neurotransmitter molecules are releasesd. The molecules diffuse across the synapse with a relay neurone setting off a new electrical impulse that travels along the relay neurone.
3. When the impulse reaches the synapse between the relay neurone and a motor neurone returning to the arm, more transmitter molecules are released. Again diffuse across the gap and start a new electrical impulse travelling along the motor neurone to the effector.
4. When the impulse reaches the effector organ, it is stimulated to respond. the impulses arrive in the muscles of the arm causing the to contract. This action moves the hand rapidly away from the scource of pain.