Neuro Flashcards
Dendrites
-signal reception
Soma (cell body)
-signal reception
Axon hillock
- signal integration
- sense change in membrane pot and initiates AP
Axon
- signal conduction
- APs conducted down to axon terminal
Pre-syn terminal
- Signal transmission
- NT released into synapse and transmits a signal to the target cell
Permeability
-incr P, incr # leak channels
current
= P + ions
ex- Na moving through a Na channel is Na current
Resting membrane pot (Vm)
- the voltage difference across the cell membrane AT REST
- inside is -70 mV
leak channels
- channels that are always open (not gated)– ion channels so they are selective
- permit unregulated flow of ions down their electrochem gradient until they are in equil
- they disrupt the conc gradient made by Na/K ATPase
Na/K ATPase
- actively transports N out and K in
- helps maintain conc gradients in order to do work. so it counters the effect of leak channels
- electrogenic pump
electrogenic pump
pumping ions in opposite directions in unequal numbers
Resting membrane pot reqs:
- electrical gradient
- chem gradient
- leak channels
- Na/K ATPase
Driving force =
= Vm - Ex
[K+] is higher on the
inside
[Na+] is higher on the
outside
[Cl-] is higher on the
outside
[A-] is higher on the
inside
-there is none outside so there is no permeability
Nernst equil pot (definition)
the membrane pot that will balance the conc for a particular ion. Conc bw the inside and outside will be balanced
Nernst equil pot =
RT/ZF ln [X]o / [X]in
(T/F) when an ion is in equil, it can still flow through a leak channel
T, it will just have no great flux
1 ion sets the membrane pot for the cell when
the cell only has leak channels for that particular ion
Why is Ca2+ very low in the inside of the cell? And describe the DF
- cell wants to tightly regulate Ca2+ bc it’s a second messenger
- DF is huge to go inside
Goldman-Hodgkin Katz eqn (definition) and why is everything normalized to K?
allows more accurate prediction of Vm bc P reflects pop of leak channels
-Normalized to K bc more K leak channels
Goldman-Hodgkin Katz eqn =
and ratios of ions
Vm = RT/F ln (pK [K]o + pNa [Na]o + pCl [Cl]i ) / (pK [K]i + pNa [Na]i pCl [Cl]o )
pK : pNa : pCl = 1.0 : 0.04 : 0.45