Voluntary Responses
A voluntary response is one where you make a conscious decision to carry out a particular action therefore it starts with your brain
An involuntary (or reflex) response does not involve the brain as the coordinator of the reaction and you are not aware you have completed it until after you have carried it out
Involuntary actions are usually ones which are essential to basic survival and are rapid, whereas voluntary responses often take longer as we consider what the consequences might be before doing it
Reflex Responses
An involuntary (or reflex) response does not involve the brain as the coordinator of the reaction and you are not aware you have completed it until after you have carried it out
This is an automatic and rapid response to a stimulus such as touching something sharp or hot
As it does not involve the brain, a reflex response is quicker than any other type of nervous response
This helps to minimise the damage to the body
A reflex
The pin (the stimulus) is detected by a pain/pressure/touch receptor in the skin
Sensory neurone sends electrical impulses to the spinal cord (the coordinator)
Electrical impulse is passed on to relay neurone in the spinal cord
Relay neurone connects to motor neurone and passes the impulse on
Motor neurone carries impulse to a muscle in the leg (the effector)
The muscle will contract and pull the foot up and away from the sharp object (the response)
Synapses
Where two neurons meet or join, they do so at a junction called a synapse
Synapses allow junctions between neurones so are important in the nervous system being a connected network of neurones
Nerve impulses can transmit across synapses and be directed along the appropriate route by them eg. to the correct part of the brain
Think about the analogy of railway points that guide the trains onto the appropriate tracks based on that train's destination.
A person is unable to feel pain in their hand and does not pull back when they touch something sharp. Which part(s) of the reflex arc might be damaged, and how could this impact their safety?
2. A doctor uses a reflex hammer to tap a patient’s knee and notices an unusually slow reflex response. What might this suggest about the patient's nervous system health? Explain how reflex testing can help in diagnosing issues within specific parts of the nervous system.
3.Imagine you accidentally touch a hot surface. Describe how the reflex arc helps protect you from a burn injury. Which steps in the reflex arc allow you to react quickly, and why is this faster than a voluntary response?
How does the reflex arc help protect the body from harm?
What is the difference between a simple reflex arc and a complex reflex arc?
How do reflex arcs differ in various parts of the body, such as the spinal cord and the brain?
Can you provide examples of common reflexes that involve the reflex arc?
How do doctors use reflex tests to assess the health of the nervous system?
Can you describe the components of a reflex arc, including sensory neurons, interneurons, and motor neurons?