Difference between revisions of "PhET-Simulations-for-Biology/C3/Neuron/English-timed"
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| − | ||Axoplasm will contain | + | ||Axoplasm will contain high concentration of '''potassium''' ions and low concentration of '''sodium''' ions. |
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| − | || Using this '''simulation''' we have learnt about, | + | || Using this '''simulation''' we have learnt about, Movement of ions across the membranes when the neuron is stimulated or at rest. |
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| − | || As an Assignment : Observe, | + | || As an Assignment : Observe, the difference between a '''gated channel''' and a '''leak channel''' |
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Revision as of 12:28, 10 October 2019
| Time | Narration |
| 00:01 | Welcome to this spoken tutorial on Neuron PhET simulation. |
| 00:07 | In this tutorial we will, Demonstrate Neuron, PhET simulation. |
| 00:14 | Here I am using, Ubuntu Linux OS version 14.04 |
| 00:20 | Java version 1.7.0 |
| 00:25 | Firefox Web Browser version 53.02.2 |
| 00:31 | To follow this tutorial, Learner should be familiar with topics in high school biology. |
| 00:39 | Using this simulation we will learn about, Movement of ions across the membranes when the neuron is stimulated or at rest. |
| 00:51 | Function of leak and gated channels |
| 00:54 | Membrane permeability. |
| 00:58 | Sequence of events that generates an action potential |
| 01:03 | Use the given link to download the simulation. |
| 01:08 | I have already downloaded Neuron simulation to my Downloads folder. |
| 01:14 | To open the simulation, right click on Neuron_en.html file. |
| 01:19 | Select Open With Firefox Web Browser option. |
| 01:24 | Simulation opens in the browser. |
| 01:27 | The simulation window shows a cross-section of an axon. |
| 01:32 | The nerve fibre or axon is like a cylinder. |
| 01:36 | The interior of axon is filled with axoplasm. |
| 01:41 | Exterior is covered with a thin axon membrane. |
| 01:45 | Different types of ion channels are present on axon membrane. |
| 01:50 | On the top-left corner of the screen, we have a zoom slider. |
| 01:55 | This helps to see the close-up view of the membrane. |
| 02:00 | On the right-side of the interface, you will see a Legend box and Show box. |
| 02:06 | Legend box shows ions and channels. |
| 02:12 | In the Show box, we have check boxes to show, All Ions ,Charges ,Concentrations Potential chart . |
| 02:23 | At the bottom of the screen we have, a box with Fast Forward, Normal and Slow Motion radio buttons. |
| 02:33 | Rewind, Play/Pause and Step buttons |
| 02:39 | Stimulate Neuron button and Reset button |
| 02:45 | In this simulation, we will see the movement of, sodium and potassium ions across the axon membrane. |
| 02:55 | About Neuron :Neurons are highly specialized cells in nervous system. |
| 03:02 | They can detect, receive and transmit different kinds of stimuli. |
| 03:09 | Drag the zoom slider, to zoom-in the axon membrane. |
| 03:14 | The ion channels are selectively permeable to different ions. |
| 03:20 | Here, 2 different types of ion channels are shown. |
| 03:25 | Leak Channel and Gated Channel. |
| 03:29 | For reference please refer to the Legend panel on the right-side of the screen. |
| 03:35 | There are sodium and potassium, Gated and Leak channels in the Legend panel. |
| 03:42 | Leak ion channels are always open. |
| 03:46 | They are responsible for the resting membrane potential. |
| 03:50 | Gated Channels open or close in response to a stimulus. |
| 03:57 | To observe the exchange of ions properly, keep the simulation speed slow. |
| 04:03 | Click on Slow Motion radio button at the bottom of the screen. |
| 04:08 | Sodium and potassium ions are seen continuously moving in and out of the membrane. |
| 04:15 | They move through the respective leak channels. |
| 04:19 | In the Show box, check against Charges and Concentrations check-boxes. |
| 04:28 | Note the concentrations of potassium and sodium ions, outside and inside the membrane. |
| 04:36 | Axoplasm will contain high concentration of potassium ions and low concentration of sodium ions. |
| 04:45 | The fluid outside the axon contains low concentration of potassium ions and high concentration of sodium ions. |
| 04:55 | This forms a concentration gradient across the membrane. |
| 05:00 | As a result, outer surface of the membrane is positively charged. |
| 05:06 | While its inner surface becomes negatively charged. |
| 05:11 | Therefore the membrane is polarised. |
| 05:16 | Resting Potential. |
| 05:19 | The electrical potential difference across the axon membrane is called Resting Potential. |
| 05:28 | In the Show box, check the check-box for Potential Chart. |
| 05:33 | To stimulate the neuron, click on Stimulate Neuron button. |
| 05:40 | Notice that Sodium ions move inside and potassium ions move outside. |
| 05:46 | During the exchange of ions charges get exchanged. |
| 05:51 | Notice the change in polarity across the axon membrane. |
| 05:56 | At this stage the nerve fibre is said to be in action potential or depolarized. |
| 06:03 | This movement of ions happen through gated channels. |
| 06:09 | Pause the simulation briefly. |
| 06:13 | Observe the increase in the membrane potential in the potential chart. |
| 06:18 | Action potentials in neuron are known as nerve impulses. |
| 06:23 | Click on Play button to start the simulation. |
| 06:27 | After a period of action potential, again reversal of the process takes place. |
| 06:34 | During this process the sodium and potassium ions move in and out. |
| 06:41 | This restores the resting potential of the membrane. |
| 06:45 | This process is called repolarization. |
| 06:49 | Now the fibre is ready to receive responsive stimulations. |
| 06:58 | Let us summarize. |
| 07:01 | In this tutorial we have demonstrated, How to use, Neuron PhET simulation. |
| 07:09 | Using this simulation we have learnt about, Movement of ions across the membranes when the neuron is stimulated or at rest. |
| 07:20 | Function of leak and gated channels. |
| 07:24 | Membrane permeability. |
| 07:27 | Sequence of events that generates an action potential. |
| 07:32 | As an Assignment : Observe, the difference between a gated channel and a leak channel |
| 07:41 | the sequence in which ion channels open or close to propagate an action potential. |
| 07:50 | The video at the following link summarizes the Spoken Tutorial project. |
| 07:56 | Please download and watch it. |
| 07:59 | The Spoken Tutorial Project team: conducts workshops using spoken tutorials and gives certificates on passing online tests. |
| 08:09 | For more details, please write to us. |
| 08:13 | Please post your timed queries on this forum. |
| 08:17 | This project is partially funded by Pandit Madan Mohan Malaviya National Mission on Teachers and Teaching. |
| 08:26 | The Spoken Tutorial Project is funded by NMEICT, MHRD Government of India. |
| 08:34 | More information on this Mission is available at this link. |
| 08:39 | This tutorial is contributed by Snehalatha Kaliappan and Meenal Ghoderao from IIT Bombay. |
| 08:46 | Thank you for joining. |
