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2016-09-29 15:24:11 -07:00
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2016-09-28-lecture03.md
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@@ -24,18 +24,18 @@ as well as general molecular signaling within neurons as any living cell might h
---
## Neurons have a negative membrane potential at rest.
## Neurons have a negative membrane potential at rest
<div style="font-size:0.7em">
<div style="font-size:0.7em; width:600px">
<div></div>
* For intracellular recordings, an electrode is placed inside a cell such that the inside of the pipette is contiguous with the inside of the cell. If this electrode is connected to a voltmeter, which records transmembrane voltage across the cell membrane, one can determine the difference in voltage between the inside and outside of the cell.
* When one does this in neurons, the microelectrode reports a negative potential called the resting potential. Always a fraction of a volt (-40 to -90 mV).
* Volts are a unit of electrochemical potential energy. 1 Volt will drive 1 coulomb of charge (6.24X10<sup>18</sup> electrons) through a resistance of 1 ohm in 1 second.
* Volts are a unit of electrochemical potential energy. 1 Volt will drive 1 coulomb of charge (6.24x10<sup>18</sup> electrons) through a resistance of 1 ohm in 1 second.
</div>
<div><img src="figs/2016-01-1112.07.56_fad9e4d.jpg" height="100px"><figcaption></figcaption></div>
<div style="margin:0 15px;"><img src="figs/neuron_model-oscilloscope_a84cec9.png" width="300px"><figcaption></figcaption></div>
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@@ -58,7 +58,7 @@ Pipe diameter ~ Resistance (ohms) = `R`
Flow rate ~ Current (amperes) = `I`
`V = IR` Ohm’s law
`V = IR` **Ohm’s law**
`I = V/R`
@@ -130,14 +130,20 @@ This figure shows these 3 types of neuronal signals.
---
## Resting Potentials of Neurons
## Resting membrane potential of neurons
<div style="font-size:0.9em;">
<div></div>
* The membrane of a nerve cell maintains an electrical polarization
* The cell is polarized: at rest, an electrical gradient is maintained across the plasma membrane (negative charge is greater inside the cell)
* The cell has a resting potential: difference in voltage across the membrane of a cell (~ -70 mV)
* The cell has a concentration gradient: difference in distribution of ions between the inside and outside of a membrane
* The cell is polarized– at rest, an electrical gradient is maintained across the plasma membrane (negative charge is greater inside the cell)
* The cell has a resting potential– difference in voltage across the membrane of a cell (~ -70 mV)
* The cell has a concentration gradient– difference in distribution of ions between the inside and outside of a membrane
</div>
<div><img src="figs/lipid_bilayer_519d59a.png" height="200px"><figcaption></figcaption></div>
<div><img src="figs/image_f9eaff2.png" height="100px"><figcaption></figcaption></div>
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@@ -252,7 +258,7 @@ There are also ion channels that form pores in the cell membrane that are select
* Requires ATP
* Helps set up the ion concentration gradients and resting membrane potential
<div><img src="figs/alberts_fig11-10-NaKatpase_f8e7b70.png" height="300px"><figcaption>Alberts *Mol Biol of the Cell* Fig. 11-10</figcaption></div>
<div><img src="figs/alberts_fig11-10-NaKatpase_f8e7b70.png" height="300px"><figcaption>Alberts *Mol Biol of the Cell* 3e Fig. 11-10</figcaption></div>
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@@ -268,7 +274,8 @@ Here is one these ion transporters— the Na-K pump that moves 3 Na out of the c
* Show ion selectivity
* Can be gated by different mechanisms
<div><img src="figs/image2_e205b47.png" height="100px"><figcaption></figcaption></div>
<figure><img src="figs/lipid_bilayer_c8a3c0c.png" height="200px"><figcaption></figcaption></figure>
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@@ -446,17 +453,6 @@ T = 20+273
==>58.26427
---
## Electrochemical equilibrium video
<div><video height=400px controls src="figs/Animation02-02ElectrochemicalEquilibrium.mp4"></video><figcaption>Neuroscience 5e Animation 2.2</figcaption></div>
Note:
---
## Examples
@@ -512,6 +508,17 @@ I = g(Vm-Ex). g = conductance, no. of open channels. (Vm-Ex) = driving force ca
---
## Electrochemical equilibrium video summary
<div><video height=400px controls src="figs/Animation02-02ElectrochemicalEquilibrium.mp4"></video><figcaption>Neuroscience 5e Animation 2.2</figcaption></div>
Note:
---
## Membrane potential influences ion fluxes
<figure><img src="figs/Neuroscience5e-Fig-02.06-1R_5d1ff2f.png" height="500px"><figcaption>Neuroscience 5e Fig. 2.6</figcaption></figure>