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Understanding the reflex arc
KEy question: why are reflexes so fast?
KEy question: why are reflexes so fast?
Task 1 - Do now
Task 1 - Do now
A quick recap
One from last lesson, last topic and last year!
Then, can you work out which is the odd one out?
Task 2 - Meet the spec
Task 2 - Meet the spec
Read through what you will need to know then answer the following question on the companion sheet.
Question
Where have you hear of a reflex before and what does it mean? Give examples
Task 3 - Linkee
Task 3 - Linkee
What do all of these images have in common?
Discus with a partner and then write your answer on the companion sheet.
Task 4 - The reflex arc
Task 4 - The reflex arc
Have a look at the first part of task 4 on the companion sheet. It shows 2 flow diagrams.
Daigram A shows a flow diagram for a normal response, such as sweating and releasing insulin.
Diagram B shows the flow diagram for a reflex such as touching someng hot.
First of all give an example of a stimulus and a response.
Then have a look at the 2 flow diagrams - can you spot the difference?
Reflex actions
Reflex actions
There are THREE different types of neurones that work together in a reflex action.
There are THREE different types of neurones that work together in a reflex action.
This creates an automatic and rapid response to a stimulus, which minimises any damage to the body from potentially harmful conditions, such as touching something hot.
Sensory
Relay
Motor
A reflex action follows this general sequence and does not involve the conscious part of the brain, which makes it much quicker.
The nerve pathway followed by a reflex action is called a reflex arc. For example, a simple reflex arc happens if we accidentally touch something hot
TAsk 5 - The big write
TAsk 5 - The big write
Reflex arc diagram for a hand touching something hot
Reflex arc diagram for a hand touching something hot
Receptor in the skin detects a stimulus (the change in temperature).
Sensory neurone sends electrical impulses to relay neurone, which are located in the spinal cord. They connect sensory neurones to motor neurones.
Motor neurone sends electrical impulses to an effector.
Effector produces a response (muscle contracts to move hand away).
Task
Using good english, write down how the body moves the hand away from the flame using reflex action.
To get good marks you should talk about the stimulus, sensory organ, different neurons involved and the response to the stimulus.
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