mod 3

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dv/dt = Iapp (t) - Iion (V) Iapp (t) = C dv/dt + Iion (V)

Imem = Cdv/dt + Iion (V)

Imem= Icap + Iion

Floating topic

inward / outward

hyperpolarization (+ -V) ion (+ +V)

restorative (+slope) regenerative (- slope)

restirative

regenerative

negative conduction

Cellular biophysics and modeling

ODE Modeling

bifurcation

phase plane analysis

phase diagrams

^ f(x) on y and state variable x on x axis (derivative as a function of underived function)

idenitfy critical points, cross at x axis is css

d/dx {f(xss)} = 0 (y axis)

determine stability by lookin at a fllow directions

preturb off its xss: n = x -x*

dn/dt= d/dt (x-x*)= f(x) - f(x*)

= f(x) = f(x* + n)

= 0 + nf' (x*) + 0

< 0 stable

speeding toward

> 0 unstable

speeding away

derivative of f(x*) is not 0 bc this is f''

via expansion taylor dn/dy = f(x*) + nf'(x*) + O(n²)

very small perturbation so third term is negligible

dn/dt = f(x) - 0

Experimental Recording Methods

voltage clamp recoding FIXED VOLTAGE, MEASURE CURRENT

applied current adjusted so that V = Vcommand

Depolarizing or depolarizing voltage

Change I app very fast

to create steps (pulses)

instantanous

dv/dt = 0 0 = Iapp - I mem (C +) I mem = Iapp

What happend to C ?????

(Depolarizaing) Pulses

steps to higher voltages)

1 - Measure

2 - Compare

3- Correct

4 - Inject

5 - Monitor

changing salt concentrations

axons dont have other than Na + an k+ channels

Subtopic

current clamp recording

Membrane potential dynamics

Action potentials (excitability)

Hodkin huxley discovered there 2 currnets in action potentials

separation and subtraction of ionic currents

LAST THREE MINUTES OF 9.1????????????
embracing currents can be isolated via ion subsists ion and digital subtraction

transient (happens when inactivate)

capacitive transient

I ion - Activation of K+ current when voltage back -10 --> -70, low driving force because ion channels decativate

only flows at instant voltage changes

I T

membrane bistability

peaks at Na becomes given a voltage and also where I will eventually steady given voltage

K+ , delayed outward current

Na+, early inward current

changing Na concent only saw change in the early inward curent

the 2 blips at +70 and +90 mv are evoke at volatges above nerst potential

Main topic