View source for PhET/C3/Neuron/English




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||'''Visual Cue'''
||'''Narration'''
|- 

|- 
|| '''Slide Number 1''' 

'''Title Slide''' 
|| Welcome to this spoken tutorial on '''Neuron PhET simulation'''. 

|- 
|| '''Slide Number 2''' 

'''Learning Objectives''' 
|| In this tutorial we will, 

Demonstrate '''Neuron''', '''PhET simulation'''. 

|- 
|| '''Slide Number 3''' 

'''System Requirement''' 
|| Here I am using, 

Ubuntu Linux OS version 14.04 

Java version 1.7.0 

Firefox Web Browser version 53.02.2 

|- 
|| '''Slide Number 4''' 

'''Pre-requisites''' 
|| To follow this tutorial, 

Learner should be familiar with topics in high school biology. 

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|| '''Slide Number 5''' 

'''Learning Goals''' 
|| Using this '''simulation''' we will learn about, 

* Movement of ions across the membranes when the neuron is stimulated or at rest

* Function of '''leak''' and '''gated channels''' 
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|| '''Slide Number 6'''
'''Learning Goals'''

|| 
* Membrane permeability 

* Sequence of events that generates an action potential 
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|| '''Slide Number 7''' 

'''Link for PhET simulation''' 

|| Use the given link to download the '''simulation'''. 

[http://phet.colorado.edu/ http://phet.colorado.edu] 

|- 
|| Open '''Downloads''' folder and show. 
|| I have already downloaded '''Neuron simulation''' to my '''Downloads''' folder. 

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|| Click on '''Neuron_en.html''' file. 

Right click on '''Open With Firefox Web Browser''' option. 

Point to '''Neuron simulation'''. 
|| To open the '''simulation''', right click on '''Neuron_en.html''' file. 

Select '''Open With Firefox Web Browser''' option. 

'''Simulation''' opens in the browser. 

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|| Point to the '''simulation''' window. 

Point to axon. 

Point to axoplasm. 

Point to axon membrane. 

Point to ion '''channels'''.

|| The '''simulation''' window shows a cross-section of an axon. 

The nerve fibre or axon is like a cylinder. 

The interior of axon is filled with axoplasm. 

Exterior is covered with a thin axon membrane. 

Different types of ion '''channels''' are present on axon membrane. 

|- 
|| Pointer on the zoom slider. 
|| On the top-left corner of the screen, we have a zoom slider. 

This helps to see the close-up view of the membrane. 

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|| Point to '''Legend''' box and '''Show''' box. 

|| On the right-side of the interface, you will see a '''Legend''' box and '''Show''' box. 

'''Legend''' box shows ions and '''channels'''. 

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|| Point to the all check-boxes.
|| In the '''Show''' box, we have check boxes to show, 

'''All Ions''' 

'''Charges''' 

'''Concentrations''' 

'''Potential chart''' 

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|| Show all the buttons at the bottom of the window. 

|| At the bottom of the screen we have, 

* a box with '''Fast Forward''', '''Normal''' and '''Slow Motion''' radio buttons
* '''Rewind''', '''Play/Pause''' and '''Step''' buttons 
* '''Stimulate Neuron''' button and 
* '''Reset''' button

|- 
|| Cursor on the neuron. 
|| In this '''simulation''', we will see the movement of, '''sodium''' and '''potassium''' ions across the axon membrane. 

|- 
|| '''Slide Number 8''' 

'''About Neuron''' 
|| About '''Neuron'''

Neurons are highly specialized cells in nervous system. 

They can detect, receive and transmit different kinds of stimuli. 

|- 
|| Drag slider to + ve side. 
|| Drag the zoom slider, to zoom-in the axon membrane. 

|- 
|| Point to ion '''channels'''. 

Point to '''Leak channel''' and '''gated channel'''. 
|| The ion '''channels''' are selectively permeable to different ions. 

Here, 2 different types of ion '''channels''' are shown. 

'''Leak Channel''' and '''Gated Channel'''. 

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|| Point to '''Legend''' panel. 

Point to '''sodium''' and '''potassium''', '''leak''' and '''gated channels''' in the '''Legend''' panel. 
|| For reference please refer to the '''Legend''' panel on the right-side of the screen. 

There are '''sodium''' and '''potassium''', '''Gated''' and '''Leak channels''' in the '''Legend''' panel. 

|- 
|| Point to '''leak channels'''. 

Point to '''gated channels'''. 
|| '''Leak''' ion '''channels''' are always open. 

They are responsible for the resting membrane potential. 

'''Gated Channels''' open or close in response to a stimulus. 

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|| Click on '''Slow Motion''' radio button at the bottom of the screen. 

Point to '''Sodium''' and '''potassium''' ions.

Point to the respective '''leak channels'''. 
|| To observe the exchange of ions properly, keep the '''simulation''' speed slow. 

Click on '''Slow Motion''' radio button at the bottom of the screen. 

'''Sodium''' and '''potassium''' ions are seen continuously moving in and out of the membrane. 

They move through the respective '''leak channels'''. 

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|| In the '''Show''' box, click on '''Charges''' and '''Concentrations''' check-boxes. 
|| In the '''Show''' box, check against '''Charges''' and '''Concentrations''' check-boxes. 

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|| Point to concentrations of '''Sodium''' and '''potassium''' ions outside and inside of the membrane. 

|| Note the concentrations of '''potassium''' and '''sodium''' ions, outside and inside the membrane. 

Axoplasm will contain 
 
* high concentration of '''potassium''' ions

* and low concentration of '''sodium''' ions 

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|| Point to concentrations outside '''Sodium''' and '''potassium''' ions. 
|| The fluid outside the axon contains 

* low concentration of '''potassium''' ions

* and high concentration of '''sodium''' ions

This forms a concentration gradient across the membrane. 

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|| Point to charges on the membrane. 

|| As a result, outer surface of the membrane is positively charged. 

While its inner surface becomes negatively charged. 

Therefore the membrane is polarised. 

|- 
|| '''Slide Number 9''' 

'''Resting Potential''' 
|| Resting Potential

The electrical potential difference across the axon membrane is called Resting Potential. 

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|| Click the check-box for '''Potential Chart''' in '''Show''' box. 
|| In the '''Show''' box, check the check-box for '''Potential Chart'''. 

|- 
|| Click on '''Stimulate Neuron''' button 
|| To stimulate the neuron, click on '''Stimulate Neuron''' button. 

|- 
|| Point to ions and '''channels'''. 

Point to the charges.

|| Notice that '''Sodium''' ions move inside and '''potassium''' ions move outside. 

During the exchange of ions charges get exchanged. 
|-

||Cursor on the membrane.

Point to '''gated channel'''.

|| Notice the change in polarity across the axon membrane.

At this stage the nerve fibre is said to be in '''action potential''' or '''depolarized'''.

This movement of ions happen through '''gated channels'''. 
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||Click on '''Pause''' button. 

||Pause the '''simulation''' briefly.  

|- 
|| Point to the peak in '''membrane potential''' chart. 
|| Observe the increase in the '''membrane potential''' in the potential chart. 

Action potentials in neuron are known as nerve impulses. 

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|| Click on '''Play''' button. 
|| Click on '''Play''' button to start the '''simulation'''. 

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|| Cursor on the membrane.

Point to '''sodium''' and '''potassium''' ions.

|| After a period of action potential, again reversal of the process takes place. 

During this process the '''sodium''' and '''potassium''' ions move in and out. 

|-

||Cursor on the interface.

Click on '''Stimulate Neuron''' button. 

|| This restores the resting potential of the membrane. 

This process is called repolarization. 

Now the fibre is ready to receive responsive stimulations. 

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|| '''Slide Number 10''' 

'''Summary''' 

|| Let us summarize, 

In this tutorial we have demonstrated, 

How to use, '''Neuron PhET simulation'''. 

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|| '''Slide Number 11''' 

'''Summary''' 

|| Using this '''simulation''' we have learnt about, 

* Movement of ions across the membranes when the neuron is stimulated or at rest

* Function of '''leak''' and '''gated channels'''
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|| '''Slide Number 12''' 

'''Summary'''
 
||
* Membrane permeability 

* Sequence of events that generates an action potential

|- 
|| '''Slide Number 13''' 

'''Assignment''' 

|| As an Assignment 

Observe, 

the difference between a '''gated channel''' and a '''leak channel'''. 

the sequence in which ion '''channels''' open or close to propagate an action potential. 

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|| '''Slide Number 14''' 

'''About Spoken Tutorial project''' 
|| The video at the following link summarizes the Spoken Tutorial project. 

Please download and watch it. 

|- 
|| '''Slide Number 15''' 

'''Spoken Tutorial workshops''' 
|| The '''Spoken Tutorial Project''' team: 

conducts workshops using spoken tutorials and gives certificates on passing online tests. 

For more details, please write to us. 

|- 
|| '''Slide Number 16''' 

'''Forum for specific questions:''' 

Do you have questions in THIS '''Spoken Tutorial'''? 

* Please visit this site 
* Choose the minute and second where you have the question. 
* Explain your question briefly 
* Someone from our team will answer them. 

|| Please post your timed queries on this forum. 

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|| '''Slide Number 17''' 

'''Acknowledgements''' 

|| This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching. 

|- 
|| '''Slide number 18''' 

'''Acknowledgement''' 
|| The Spoken Tutorial Project is funded by '''NMEICT''', '''MHRD Government of India'''. 

More information on this Mission is available at this link. 
|- 
|| 
|| This tutorial is contributed by Snehalatha Kaliappan and Meenal Ghoderao from IIT Bombay. 

Thank you for joining. 

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