B10.3 Reflex actions

Question 1

What are reflexes?

Answer 1

Automatic responses that happen without giving the time to think

Question 2

What are reflexes for?

Answer 2

Help avoid danger because they happen so fast

Can help you breathe and move food through your digestive system without you thinking about it

Question 3

Are reflexes automatic?

Answer 3

Yes - they do not involve the conscious part of your brain as they are automatic and rapid

Question 4

What are relay neurones?

Answer 4

These connect a sensory neurone and a motor neurone and are found in the CNS

Question 5

What type of neurones do reflexes work with?

Answer 5

Sensory neurones
Motor neurones
Relay neurones

Question 6

What is the step by step process of how reflexes work?

Answer 6

Electrical impulse passes from receptor along the sensory neurone to the CNS. Passes along a relay neurone and straight back to the motor neurone. From here - the impulse arrives at the effector organ. Effector organ will be a muscle or a gland

Question 7

What is a reflex arc?

Answer 7

The nerve pathway followed by a reflex action is called a reflex arc

Question 8

What happens when an impulse arrives at the junction between two neurones?

Answer 8

Chemicals are released that cross the synapse and arrive at receptor sites on the next neurone

Question 9

What are synapses?

Answer 9

Physical gaps between the neurones

Question 10

How do electrical impulses travel when there is a synapse?

Answer 10

They diffusion of the chemicals across the synapse is slower than the electrical impulse in the neurones but it makes it possible for the impulse to cross the gap between them

Question 11

What happens if you touched a hot object?

Answer 11

Receptor in your skin is stimulated. Electrical impulse from a receptor passes along a sensory neurone to the CNS

When the impulse from the sensory neurone arrives at the synapse with a relay neurone a chemical is released. The chemical diffuses across the synapse to the relay neurone where it sets off a new electrical impulse

When the impulse reach the synapse between the relay neurone and a motor neurone another chemical is released. Starts of a new electrical impulse down the motor neurone to the effector

When impulse reaches effector organ. Causes muscles in the arm to contract. Moves hand rapidly away from the source of pain. If effector organ is glands - it secretes chemical substances

Question 12

What happens in a reflex action that is different from a normal conscious action?

Answer 12

The coordinator is a relay neurone wither in the spinal cord or in the unconscious areas of the brain

Question 13

What are the main stages of a reflex arc?

Answer 13

Stimulus 
Receptor
Sensory neurone
Relay neurone
Motor neurone
Effector
Response