Grade+10+1.2+Perception

PERCEPTION, REACTION AND CONTROL
So, what exactly is perception? Does everyone have the same perception of the world around us? These are questions that are hard (if not impossible) to answer with our current level of understanding. Watch the video which follows and we will discuss its relevance in class.

media type="youtube" key="12u1nA7bXzc" width="560" height="315" [|Morpheus vs Neo]

Here is a report from the BBC about a television programme which investigated the affect that colour seems to have on our lives.

[|Do you see what I see?]

In order to understand how our perceptions and senses work we need to begin our investigation with the nervous system. First we need to understand the basic structure and function of the nerve cells (neurons). You should have some understanding of this by studying your class notes. For anyone who has some difficulties with the concepts involved here are some links that will provide more information for you.

[|Neuron structure and functions]

A teacher named Leslie Samuel provided this video.

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Now that we have a good understanding of the structures involved we need to see how the nerve impulses move from one side of the neuron to the other. These impulses are actually called ´action potentials´ and their movement across the neuron is similar to that seen in the video below.

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However, this does not explain the process involved. Harvard University has provided some fantastic reference tools that will enable you to understand the process of the action potential. Watch the animation, play the ´game´ and you will become an expert (hopefully) on how action potentials work!

[|Harvard outreach: The action potential]

A short summary video is provided here.

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There are also some other videos that may help you understand the concepts, the first is, again, thanks to our friend Leslie Samuel.

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Nerve Impulse Animation-and Knowledge Check

Once you have understood the action potential process, we need to move on to the next concept....synaptic transmission. One important question that needs to be answered is... what exactly is a synapse?

The answer to this and other questions that we will ask can be found at the London Science Museum website. [|London Science Museum- What is a synapse?] Chemical Synapse and Knowledge Check A very good video of the action potential and synaptic transmission processes may be viewed below. The images are small so the window size has been set to maximum.

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For those who are still a little unsure of the process involved... Harvard has, once again, provided a great animation game to help you.

[|Harvard outreach: Synaptic transmission]

One example of how our sensory, inter and motor neurons work together may be seen in the process known as the reflex arc. In this process a stimulus is received by the sensory neuron, travels to the spinal cord where is transferred to an inter neuron and then is passed directly to the motor neuron so as to create an immediate response. They produce our reflex actions (where we can literally perform an action without thinking). The brain is **INFORMED** of the action (and can even prevent it in some circumstances) but the important concept is that the action potential that creates the final motion is produced initially by the sensory neuron and not from a conscious decision in the brain.



Here is an animation that may help you to visualise the process better.

media type="custom" key="24863198" align="center" The overall concepts of perception, reaction and control