fall2021, lect03

neurophysiology1.md

@@ -6,7 +6,9 @@
 * Synaptic transmission
 * Neurotransmitters, receptors, and their effects (second messenger systems, molecular signaling within neurons)
 
+<div style="font-size:0.5em;">
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+</div>
 
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@@ -61,7 +63,9 @@ Flow rate ~ Current (amperes) = `I`
 
 </div>
 
-<div style="margin:0 15px"><img src="figs/ScreenShot2016-01-10at3.49.52PM_f9a9f96.png" height="300px"><figcaption>M. Banzi Fig. 4-4, *Getting Started with Arduino* isbn:9781449363338</figcaption></div>
+<div style="margin:0 15px"><img src="figs/ScreenShot2016-01-10at3.49.52PM_f9a9f96.png" height="300px"><figcaption>
+
+M. Banzi Fig. 4-4, *Getting Started with Arduino* isbn:9781449363338</figcaption></div>
 
 
 
@@ -77,15 +81,15 @@ Voltage
 *voltmeter, ammeter*
 
 Current  
-: measured in amperes is the flow of electric charge across a surface at the rate of one coulomb per second. Used to express the flow rate of electric charge.  
+: measured in amperes is the flow of electric charge across a surface at the rate of one coulomb per second. **Used to express the flow rate of electric charge**.  
 : So imagine the rate of water flow in this water pump as the the flow of electric charge across a cell membrane. What is the charge that is moving for a cell? Monovalent and divalent atoms like Na⁺, K⁺, Cl⁻, and Ca²⁺.  
 
-*1A equivalent to one coulomb (roughly 6.241×10^18 times the elementary charge) per second*  
-*coulomb = charge (symbol: Q or q) transported by a constant current of one ampere in one second. 1C equivalent to a charge of approximately 6.242×10^18 protons or electrons.*  
-*elementary positive charge: This charge has a measured value of approximately 1.6021766208×10^−19 coulombs*  
+- *1A equivalent to one coulomb (roughly 6.241×10^18 times the elementary charge) per second*  
+- *coulomb = charge (symbol: Q or q) transported by a constant current of one ampere in one second. 1C equivalent to a charge of approximately 6.242×10^18 protons or electrons.*  
+- **elementary positive charge: This charge has a measured value of approximately 1.6021766208×10^−19 coulombs**  
 
 Resistance  
-: is the difficulty to pass a current through a conductor measured in ohms.  
+: **is the difficulty to pass a current through a conductor measured in ohms.**  
 : Image the diameter of a pipe or a valve that you can regulate to be the resistance  
 : inverse of resistance is conducance *g* measured in siemens (S)  
 : for studying neuronal excitability rewriting Ohm's law as I = g(Vm-Ex) is most useful. g = conductance, no. of open channels. (Vm-Ex) = driving force causing either positive or negative current.  
@@ -114,21 +118,23 @@ electricity
 
 ## Electrical signals
 
-* Can be generated by changing the membrane potential of the neuron
-* Receptor potentials can be generated from the activation of sensory receptors, from touch, light, sound, and heat
+* Generated by changing the membrane potential of the neuron
+* Receptor potentials can be generated from the activation of sensory receptors: from touch, light, sound, taste, heat...
 * Synaptic potentials are generated at the post-synaptic membrane between two neurons
-* Action potentials are the high-amplitude, fast timing, regenerative signal that propagate a long distance
+* Action potentials are the high-amplitude, fast timing, regenerative signals that propagate a long distance
 
 Note:
 
 Signals in neurons can be generated by changing the membrane potential.  
-
 This includes receptor potentials inside your body’s sensory neurons for touch, heat, light, and sound.
 
 And synaptic potentials are the changes in membrane potential at synapses that underly the transfer of information from neuron to neuron.
 
 Action potentials are the large electrical spikes or impulses that allow neuronal signals to propagate over long distances, including nerves centimeters to meters long.
 
+signal (wn, noun)   
+: an electric quantity (voltage or current or field strength) whose modulation represents coded information about the source from which it comes
+
 ---
 
 ## Types of electrical signals in neurons
@@ -150,7 +156,7 @@ To understand the basis of these electrical signals we first need to learn about
 
 ---
 
-## What is baseline? The resting membrane potential of neurons
+## What is baseline? The "resting" membrane potential of neurons
 
 <div style="font-size:0.9em;">
 <div></div>
@@ -170,7 +176,7 @@ Note:
 
 I said that the resting membrane potential is more negative inside the neuron with respect to its extracellular space– this is because of the lipid bilayer and its transmembrane proteins which together make a functional cell membrane
 
-We can think of the cell, a bit like American politics, is polarized with one side more negative and the other being more positive
+We can think of the cell, a bit like American politics, is polarized. 
 
 This polarization of the cell results in a potential difference across the membrane (remember our water pump example) of about -70 mV
 
@@ -289,7 +295,9 @@ 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* 3e 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>
 
 
 Note:
@@ -713,7 +721,6 @@ That is semipermeable containers with some capactity for self-replication
 | calcium (Ca<sup>2+</sup>), squid | 0.0001 | 10 | 100000 |
 | calcium (Ca<sup>2+</sup>), mammal | 0.0001 | 1–2 | 10000 |
 
-<figcaption>see also Neuroscience 5e Table 2.1</figcaption>
 </div>
 
 
@@ -764,9 +771,13 @@ Alan Hodgkin, Andrew Huxley, Bernard Katz
 
 ## Squid giant axon
 
-<div><img src="figs/Squid_Loligo_pealei_cbafe46.jpg" height="300px"><figcaption>Atlantic squid, *Loligo pealei*</figcaption></div>
+<div><img src="figs/Squid_Loligo_pealei_cbafe46.jpg" height="300px"><figcaption>
 
-<div><iframe src="https://www.youtube.com/embed/I6jxrxcLxiI" width="560" height="315"></iframe><figcaption>Squid giant axon electrophysiology</figcaption></div>
+Atlantic squid, *Loligo pealei*</figcaption></div>
+
+<div><iframe src="https://www.youtube.com/embed/I6jxrxcLxiI" width="560" height="315"></iframe><figcaption>
+
+Squid giant axon electrophysiology</figcaption></div>
 
 
 Note:
@@ -775,7 +786,9 @@ Note:
 
 ## K⁺ concentration gradient determines resting membrane potential
 
-<figure><img src="figs/Neuroscience5e-Fig-02.08-0_40bc007.png" height="400px"><figcaption>Neuroscience 5e/6e fig. 2.8; Hodgkin and Katz *J. Physiol* 1949</figcaption></figure>
+<figure><img src="figs/Neuroscience5e-Fig-02.08-0_40bc007.png" height="400px"><figcaption>
+
+Neuroscience 5e/6e fig. 2.8; Hodgkin and Katz *J. Physiol* 1949</figcaption></figure>
 
 
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@@ -829,7 +842,9 @@ Their experiment was to lower Na concentrations in the extracellular medium—
 
 ## The action potential as measured by Hodgkin, Huxley, and Katz
 
-<figure><img src="figs/hodkin-huxley-nature-1939-AP_d30dfee.png" height="400px"><figcaption>Adapted from Hodgkin and Huxley *Nature* 1939</figcaption></figure>
+<figure><img src="figs/hodkin-huxley-nature-1939-AP_d30dfee.png" height="400px"><figcaption>
+
+Adapted from Hodgkin and Huxley *Nature* 1939</figcaption></figure>
 
 
 Note:
@@ -847,7 +862,9 @@ Capacitance (farads)
 
 ## Role of sodium in the generation of an action potential
 
-<figure><figcaption class="big">Lowering Na⁺ decreases both the rate and the rise of an action potential</figcaption><img src="figs/Neuroscience5e-Fig-02.09-1R_2c02203.png" height="400px"><figcaption>Neuroscience 5e/6e Fig. 2.9; Hodgkin and Katz *J. Physiol* 1949</figcaption></figure>
+<figure><figcaption class="big">Lowering Na⁺ decreases both the rate and the rise of an action potential</figcaption><img src="figs/Neuroscience5e-Fig-02.09-1R_2c02203.png" height="400px"><figcaption>
+
+Neuroscience 5e/6e Fig. 2.9; Hodgkin and Katz *J. Physiol* 1949</figcaption></figure>
 
 
 Note:
@@ -858,7 +875,9 @@ When Hodgkin and Katz did this low extracellular Na experiment, the AP had a sma
 
 ## Role of sodium in the generation of an action potential
 
-<figure><img src="figs/Neuroscience5e-Fig-02.09-2R_6ca6c4f.png" height="400px"><figcaption>Neuroscience 5e/6e Fig. 2.9; Hodgkin and Katz *J. Physiol* 1949</figcaption></figure>
+<figure><img src="figs/Neuroscience5e-Fig-02.09-2R_6ca6c4f.png" height="400px"><figcaption>
+
+Neuroscience 5e/6e Fig. 2.9; Hodgkin and Katz *J. Physiol* 1949</figcaption></figure>
 
 Note: